Polyploidization is one of the most crucial pathways in introducing speciation and broadening biodiversity, especially in the Plant Kingdom. Although the majority of studies have focused only on allopolyploid or disom...Polyploidization is one of the most crucial pathways in introducing speciation and broadening biodiversity, especially in the Plant Kingdom. Although the majority of studies have focused only on allopolyploid or disomic polyploids, polysomic polyploid species have occurred frequently in higher plants. Due to the occurrence of the capabilities of more copies of alleles in a locus which can have additive dosage effects and/or allelic interactions, polysomic polyploids can lead to unique gene regulations to silence or adjust the expression level to create variations in organ size, metabolic products, and abiotic stress tolerance and biotic stress resistance, etc. This review aims to comprehensively summarize the contemporary understanding and findings concerning the molecular mechanisms of gene expression as well as gene regulation in natural typed and resynthesized polysomic polyploid plants. The review investigates the molecular level of phenomena in polysomic polyploid plants such as 1) typically enlarging organ size and stabilizing meiosis, 2) increasing phytochemical content and metabolic products, 3) enhancing the ability to adapt with biotic and abiotic stress, and 4) changing in gene regulation to silence or adjust the expression levels involve in sequence elimination, methylation, gene suppression, subfunctionalization, neo-functionalization, and transposon activation.展开更多
Most Rhododendron species are ornamental flowering species widely distributed in Asia,North America,and West Europe.Rhododendron fortunei,one of the endemic Rhododendron species in China,has beautiful flowers with bri...Most Rhododendron species are ornamental flowering species widely distributed in Asia,North America,and West Europe.Rhododendron fortunei,one of the endemic Rhododendron species in China,has beautiful flowers with bright colors and is being exploited to meet the needs of the flower market.Polyploid plants usually show superiority in growth,disease resistance,and adaption over their diploid relatives.Here,we report the first case of polyploid induction in R.fortunei.In order to induce polyploidy in R.fortunei,germinating seeds were treated with different concentrations of oryzalin for 16 h.By evaluating ploidy level with flow cytometry,a total of 34 polyploid R.fortunei lines,including 27 tetraploid lines and seven octoploid lines,were obtained.A comparison of treatments indicated that 7.5 mg L^-1 oryzalin was the optimal concentration for polyploid induction in seeds of R.fortunei.Compared with diploid plants,tetraploid and octoploid plants exhibited slower growth rates and had thicker and rounder curled leaves with more leaf epidermal hairs.Moreover,larger stomata at lower density were also observed in the leaves of polyploid plants.Chlorophyll contents were also significantly increased in polyploid plants,which leads to a darker green leaf color.Both small and large individuals exhibiting the same characteristics were observed among the obtained tetraploid plants.Overall,our study establishes a feasible method for polyploid induction in R.fortunei,thus providing a basis for breeding new R.fortunei varieties.展开更多
[Objective] This study aimed to explore the origin and evolution of poly- poids in Parakmeria Hu et Cheng through LEAFY gene clone and sequence analysis. [Method] In this study, LEAFY gene in Parakmeria species and it...[Objective] This study aimed to explore the origin and evolution of poly- poids in Parakmeria Hu et Cheng through LEAFY gene clone and sequence analysis. [Method] In this study, LEAFY gene in Parakmeria species and its relative genera was cloned and sequenced using molecular biology methods. With reference to LEAFY gene sequence published by NCBI, the origin pattern of polypoids in Parakmeria was explored and reasons for the distribution layout of different polypoids were analyzed through sequence alignment and phylogenetic analysis. [Result] Different Magnoliaceae species can be distinguished using the LEAFY gene, and there was a length polymorphism found in the 3＋ end of the LEAFY gene, which can be used to divide Magnoliaceae plants of different species or in different genera, thus of high application value. [Conclusion] Most Parakmeria tetraploids are produced by polyploidization of homologous chromosomes, while Parakmeria hexaploids are chiefly produced by both polyploidization of homologous chromosomes and heterologous hybridization.展开更多
Wild peanut(Arachis)species are promising sources of disease resistance for improving peanut cultivars.The objective of this study was to assess cross-compatibility among cultivated and wild peanuts in crosses between...Wild peanut(Arachis)species are promising sources of disease resistance for improving peanut cultivars.The objective of this study was to assess cross-compatibility among cultivated and wild peanuts in crosses between eight peanut cultivars and 27 wild species carrying the A,B,E,Ex,F,K,P,and H genomes.Embryo culture and chromosome doubling led to polyploids representing hybrids between cultivated peanut and A.stenosperma,A.macedoi,A.duranensis,A.villosa,and A.diogoi.The first two showed greater resistance to bacterial wilt than their cultivated parents.DNA markers were developed for verifying the hybrids and for identifying translocation or introgression lines with alien chromosome fragments.展开更多
Subtropical evergreen broad-leaved trees are usually vulnerable to freezing stress,while hexaploid wild Camellia oleifera shows strong freezing tolerance.As a valuable genetic resource of woody oil crop C.oleifera,wil...Subtropical evergreen broad-leaved trees are usually vulnerable to freezing stress,while hexaploid wild Camellia oleifera shows strong freezing tolerance.As a valuable genetic resource of woody oil crop C.oleifera,wild C.oleifera can serve as a case for studying the molecular bases of adaptive evolution to freezing stress.Here,47 wild C.oleifera from 11 natural distribution sites in China and 4 relative species of C.oleifera were selected for genome sequencing.“Min Temperature of Coldest Month”(BIO6)had the highest comprehensive contribution to wild C.oleifera distribution.The population genetic structure of wild C.oleifera could be divided into two groups:in cold winter(BIO6≤0℃)and warm winter(BIO6>0℃)areas.Wild C.oleifera in cold winter areas might have experienced stronger selection pressures and population bottlenecks with lower N_(e) than those in warm winter areas.155 singlenucleotide polymorphisms(SNPs)were significantly correlated with the key bioclimatic variables(106 SNPs significantly correlated with BIO6).Twenty key SNPs and 15 key copy number variation regions(CNVRs)were found with genotype differentiation>50%between the two groups of wild C.oleifera.Key SNPs in cis-regulatory elements might affect the expression of key genes associated with freezing tolerance,and they were also found within a CNVR suggesting interactions between them.Some key CNVRs in the exon regions were closely related to the differentially expressed genes under freezing stress.The findings suggest that rich SNPs and CNVRs in polyploid trees may contribute to the adaptive evolution to freezing stress.展开更多
Hibiscus Linn.,an angiosperm genus belonging to Malvaceae,Malvales,is mainly distributed in tropic and subtropic regions.Numerous species within the Hibiscus genus exhibit large and visually appealing flowers that are...Hibiscus Linn.,an angiosperm genus belonging to Malvaceae,Malvales,is mainly distributed in tropic and subtropic regions.Numerous species within the Hibiscus genus exhibit large and visually appealing flowers that are highly prized for their ornamental beauty and enjoy widespread admiration.For instance,H.syriacus serves as the national flower of South Korea,H.rosa-sinensis is favored as the floral emblem of Malaysia,and Chengdu city has earned the moniker"City of H.mutabilis"owing to its substantial cultivation.展开更多
As a high-value eudicot family,many famous horticultural crop genomes have been deciphered in Oleaceae.However,there are currently no bioinformatics platforms focused on empowering genome research in Oleaceae.Herein,w...As a high-value eudicot family,many famous horticultural crop genomes have been deciphered in Oleaceae.However,there are currently no bioinformatics platforms focused on empowering genome research in Oleaceae.Herein,we developed the first comprehensive Oleaceae Genome Research Platform(OGRP,https://oleaceae.cgrpoee.top/).In OGRP,70 genomes of 10 Oleaceae species and 46 eudicots and 366 transcriptomes involving 18 Oleaceae plant tissues can be obtained.We built 34 window-operated bioinformatics tools,collected 38 professional practical software programs,and proposed 3 new pipelines,namely ancient polyploidization identification,ancestral karyotype reconstruction,and gene family evolution.Employing these pipelines to reanalyze the Oleaceae genomes,we clarified the polyploidization,reconstructed the ancestral karyotypes,and explored the effects of paleogenome evolution on genes with specific biological regulatory roles.Significantly,we generated a series of comparative genomic resources focusing on the Oleaceae,comprising 108 genomic synteny dot plots,1952225 collinear gene pairs,multiple genome alignments,and imprints of paleochromosome rearrangements.Moreover,in Oleaceae genomes,researchers can efficiently search for 1785987 functional annotations,22584 orthogroups,29582 important trait genes from 74 gene families,12664 transcription factor-related genes,9178872 transposable elements,and all involved regulatory pathways.In addition,we provided downloads and usage instructions for the tools,a species encyclopedia,ecological resources,relevant literatures,and external database links.In short,ORGP integrates rich data resources and powerful analytical tools with the characteristic of continuous updating,which can efficiently empower genome research and agricultural breeding in Oleaceae and other plants.展开更多
Fruit quality traits play an important role in consumption of kiwiberry(Actinidia arguta).The genetic basis of fruit quality traits in this woody,perennial and dioecious fruit crop remains largely unknown.This study a...Fruit quality traits play an important role in consumption of kiwiberry(Actinidia arguta).The genetic basis of fruit quality traits in this woody,perennial and dioecious fruit crop remains largely unknown.This study aimed to identify the underlying genetic basis of fruit quality traits in A.arguta,using a single nucleotide polymorphism(SNP)genetic linkage map previously developed in a tetraploid F1 population of‘Ruby-3’בKuiLv-M’.The F1 population was phenotyped over three years(2020–2022)for fruit quality traits,including skin color,flesh color,fruit weight,fruit diameter,total soluble solids,fruit longitudinal diameter and fruit shape index.A total of nine QTLs were detected for five traits,explaining 10%–32%of the trait variation.For fruit color,the support interval of a major QTL on LG9 contained an MYB transcription factor MYB110,which was previously demonstrated to control color regulation in kiwifruit,thus suggesting that the MYB110 is the candidate gene for fruit color in kiwiberry.The linked marker for fruit color was validated in an F1 population and 25 kiwiberry cultivars.In conclusion,the knowledge obtained through the QTL mapping is applicable to improve the efficiency and cost-effectiveness in kiwiberry breeding.展开更多
Allopolyploids often exhibit advantages in vigor and adaptability compared to diploids.A long-term goal in the economically important Brassica genus has been to develop a new allohexaploid crop type(AABBCC)by combinin...Allopolyploids often exhibit advantages in vigor and adaptability compared to diploids.A long-term goal in the economically important Brassica genus has been to develop a new allohexaploid crop type(AABBCC)by combining different diploid and allotetraploid crop species.However,early-generation allohexaploids often face challenges like unstable meiosis and low fertility,and the phenotypic performance of these synthetic lines has rarely been assessed.This study analyzes agronomic traits,fertility,and genome stability in ArArBcBcCcCc lines derived from four crosses between B.carinata and B.rapa after 9–11 selfing generations.Our results demonstrate polyploid advantage in vigor and seed traits,considerable phenotypic variation,and high fertility and genome stability.Meanwhile,parental genotypes significantly influence outcomes in advanced allohexaploids.Structural variants,largely resulting from A–C homoeologous exchanges,contribute to genomic variation and influence hexaploid genome stability,with the A sub-genome showing the highest variability.Both positive and negative impacts of SVs on fertility and seed weight are observed.Pseudo-euploids,frequently appearing,do not significantly affect fertility or other agronomic traits compared to euploids,indicating a potential pathway toward a stable allohexaploid species.These findings provide insights into the challenge and potential for developing an adaptable and stable Brassica hexaploid through selection.展开更多
Polyploidization is a commonly employed strategy in crop breeding to augment genetic diversity,particularly leveraging the distinctive benefits of additional progressive heterosis or multi-generation heterosis unique ...Polyploidization is a commonly employed strategy in crop breeding to augment genetic diversity,particularly leveraging the distinctive benefits of additional progressive heterosis or multi-generation heterosis unique to polyploidy.Despite genetic disparities between polyploids and diploids,challenges stem from reproductive anomalies,complicating genetic investigations in polyploid systems.Through nearly two decades of intensive research,our team has effectively generated a series of fertile tetraploid lines known as neo-tetraploid rice(NTR),facilitating comparative genetic studies between diploid and tetraploid rice.In this study,we identified diploid counterparts(H3d and H8d)for two NTR lines[Huaduo 3(H3)and Huaduo 8(H8)]and utilized them to create diploid and tetraploid fertile F_(2) populations to assess genotype segregation ratios,recombination rates,and their impact on QTL mapping via bulked segregant analysis combined with sequencing(BSA-seq).Additionally,we assessed yield heterosis in F_(1) and F_(2) generations of two tetraploid populations(H3×H8 and T449×H1),revealing evidence of multi-generation heterosis in polyploid rice.These findings provide valuable insights into the advantages and challenges of polyploid rice breeding.展开更多
Genome polyploidy has been revealed to result in evolutionary advantages and novelties,and therefore,polyploid aquatic animals may possess excellent traits of economic interest including rapid growth,extensive adaptab...Genome polyploidy has been revealed to result in evolutionary advantages and novelties,and therefore,polyploid aquatic animals may possess excellent traits of economic interest including rapid growth,extensive adaptability and disease resistance.For this reason,numerous species of natural polyploid fishes,such as common carp,gibel carp,crucian carp,salmon,and sturgeon,were chosen as important target species for aquaculture.Many artificial polyploids have been commercially utilized for aquaculture and most of them were created from natural polyploid fishes of the Cyprinidae and Salmonidae.Thanks to the easy mass production and better economic traits in growth and flesh quality,the synthetized autopolyploids or allopolyploids from natural polyploid species in cyprinid fishes have been extensively applied to aquaculture throughout China.This review outlines polyploidy advantages and innovative opportunities,lists natural polyploid species used in aquaculture,and summarizes artificial polyploids that have been induced or synthetized,and used in aquaculture.Moreover,some main research trends on polyploid utilization and ploidy manipulation of aquaculture animals are also introduced and discussed in the review.展开更多
"Synthetic"allopolyploids recreated by interspecific hybridization play an important role in providing novel genomic variation for crop improvement.Such synthetic allopolyploids often undergo rapid genomic s..."Synthetic"allopolyploids recreated by interspecific hybridization play an important role in providing novel genomic variation for crop improvement.Such synthetic allopolyploids often undergo rapid genomic structural variation(SV).However,how such SV arises,is inherited and fixed,and how it affects important traits,has rarely been comprehensively and quantitively studied in advanced generation synthetic lines.A better understanding of these processes will aid breeders in knowing how to best utilize synthetic allopolyploids in breeding programs.Here,we analyzed three genetic mapping populations(735 DH lines)derived from crosses between advanced synthetic and conventional Brassica napus(rapeseed)lines,using whole-genome sequencing to determine genome composition.We observed high tolerance of large structural variants,particularly toward the telomeres,and preferential selection for balanced homoeologous exchanges(duplication/deletion events between the A and C genomes resulting in retention of gene/chromosome dosage between homoeologous chromosome pairs),including stable events involving whole chromosomes("pseudoeuploidy").Given the experimental design(all three populations shared a common parent),we were able to observe that parental SV was regularly inherited,showed genetic hitchhiking effects on segregation,and was one of the major factors inducing adjacent novel and larger SV.Surprisingly,novel SV occurred at low frequencies with no significant impacts on observed fertility and yield-related traits in the advanced generation synthetic lines.However,incorporating genome-wide SV in linkage mapping explained significantly more genetic variance for traits.Our results provide a framework for detecting and understanding the occurrence and inheritance of genomic SV in breeding programs,and support the use of synthetic parents as an important source of novel trait variation.展开更多
Plant polyploidy often occurs in conjunction with higher yield and superior quality.Therefore,obtaining polyploid germplasms is a significant part of breeding.The oil-tea Camellia tree is an important native woody pla...Plant polyploidy often occurs in conjunction with higher yield and superior quality.Therefore,obtaining polyploid germplasms is a significant part of breeding.The oil-tea Camellia tree is an important native woody plant that produces high-quality edible oil and includes many species of Camellia with different ploidies.However,whether higher ploidy levels in oil-tea Camellia trees are related to better traits remains unclear.In this study,the ploidy levels of 30 different oil-tea Camellia strains in three different species in the Sect.Paracamellia were determined by flow cytometry and chromosome preparation,and the phenotypic characteristics and fatty acid compositions of the fruits were examined by field observations and laboratory analyses.The correlations between the ploidy level of oil-tea Camellia and the main traits of the fruit were investigated.Our results showed that 10 Camellia lanceoleosa strains were diploid,10 Camellia meiocarpa strains were tetraploid and 10 Camellia oleifera strains were hexaploid.Hexaploid C.oleifera had larger fruit size and weight,more seeds per fruit,greater seed weight per fruit,higher oil content and greater yield per crown width than tetraploid C.meiocarpa and diploid C.lanceoleosa,but their fruit peel thickness and fresh seed rate were significantly lower,and these traits were significantly correlated with ploidy level.In addition,in terms of fatty acid composition,hexaploid C.oleifera had a higher oleic acid content than tetraploid C.meiocarpa and diploid C.lanceoleosa,but their linoleic acid,linolenic acid and arachidonic acid contents were lower.The contents of palmitic acid,stearic acid and total unsaturated fatty acids were not significantly correlated with ploidy level.In conclusion,certain correlations exist between the main characteristics of oil-tea Camellia fruit and the ploidy level,and increasing the ploidy level led to an increase in fruit yield with no effect on oil composition.The discovery of variations in the main characteristics of oil-tea Camellia fruit with different ploidies will facilitate germplasm innovation and lay a foundation for ploidy breeding and mechanistic research on fruit traits.展开更多
Polyploidization in plants often leads to increased cell size and grain size,which may be affected by the increased genome dosage and transcription abundance.The synthesized Triticum durum(AABB)-Hay-naldia villosa(WM)...Polyploidization in plants often leads to increased cell size and grain size,which may be affected by the increased genome dosage and transcription abundance.The synthesized Triticum durum(AABB)-Hay-naldia villosa(WM)amphiploid(AABBM)has significantly increased grain size,especially grain length,than the tetraploid and diploid parents.To investigate how polyploidization affects grain development at the transcriptional level,we perform transcriptome analysis using the immature seeds of T.durum,H.villosa,and the amphiploid.The dosage effect genes are contributed more by differentially expressed genes from genome V of H.villosa.The dosage effect genes overrepresent grain development-related genes.Inter-estingly,the vernalization gene TaVRN1 is among the positive dosage effect genes in the T.durum-H.villosa and T.turgidum-Ae.tauschii amphiploids.The expression levels of TaVRN1 homologs are positively correlated with the grain size and weight.The TaVRN1-B1 or TaVRN1-D1 mutation shows delayed florescence,decreased cell size,grain size,and grain yield.These data indicate that dosage effect genes could be one of the important explanations for increased grain size by regulating grain development.The identification and functional validation of dosage effect genes may facilitate the finding of valuable genes for improvingwheat yield.展开更多
Coptis chinensis Franch.,also named Chinese goldthread is a member of Ranunculaceae in the order Ranunculales and represents an important lineage of early eudicots with traditional medicinal value.In our study,by usin...Coptis chinensis Franch.,also named Chinese goldthread is a member of Ranunculaceae in the order Ranunculales and represents an important lineage of early eudicots with traditional medicinal value.In our study,by using syntenic analysis combined with phylogenomic analysis of C.chinensis and four other representative genomes from basal and core eudicots,we confirmed that the WGD event in C.chinensis was shared by Aquilegia coerulea and Papaver somniferum L.and quickly occurred after Ranunculales diverged from other eudicots,likely a Ranunculales common tetraploidization(RCT).The synonymous nucleotide substitutions at synonymous sites distribution of syntenic blocks across these genomes showed that the evolutionary rate of the P.somniferum genome is faster than that of the C.chinensis genome by approximately 13.7%,possibly due to Papaveraceaes having an additional special tetraploidization event(PST).After Ks correction,the RCT dated to 115—130 million years ago(MYA),which was close to the divergence of Ranunculaceaes and Papaveraceaes approximately115.45—130.51 MYA.Moreover,we identified homologous genes related to polyploidization and speciation and constructed multiple sequence alignments with different reference genomes.Notably,the event-related subgenomes in the basal genomes all showed genomic fractionation bias,suggesting a likely allopolyploid nature of the RCT,PST and T-Alpha and T-Beta events in Tetracentron sinense.In addition,we detected that the sixteen P450 subfamilies were markedly expanded in the genomes of Ranunculales,and most of them were related to the RCT and PST events.We constructed a new platform for Early Eudicot Comparative Genomic Research(http://www.cgrpoee.top/index.html)to store more information.In summary,our findings support the WGD of C.chinensis shared by Ranunculales,which is likely an allotetraploidization event.This present effort offered new insights into the evolution of key polyploidization events and the genes related to secondary metabolites during the diversification of early eudicots.展开更多
Scientific knowledge about the ancestral genome of core eudicot plant kingdom can potentially have profound impacts on both basic and applied research,including evolution,genetics,genomics,ecology,agriculture,forestry...Scientific knowledge about the ancestral genome of core eudicot plant kingdom can potentially have profound impacts on both basic and applied research,including evolution,genetics,genomics,ecology,agriculture,forestry,and global climate.To investigate which plant conserves best the core eudicots common ancestor genome,we compared Arcto-Tertiary relict Nyssaceae and 30 other eudicot plant families.The genomes of Davidia involucrata(a known living fossil),Camptotheca acuminata and Nyssa sinensis,one per existent genus of Nyssaceae,were performed comparative genomic analysis.We found that Nyssaceae originated from a single Nyssaceae common tetraploidization event(NCT)-autotetraploidization 28-31 Mya after the core eudicot common hexaploidization(ECH).We identified Nyssaceae orthologous and paralogous genes,determined its chromosomal evolutionary trajectory,and reconstructed the Nyssaceae most recent ancestor genome.D.involucrata genome contained the entire seven paleochromosomes and 17 ECH-generated eudicot common ancestor chromosomes and was the slowest in mutation among the analyzed 42 species of 31 plant families.Combing both its high retention of paleochromosomes and its low mutation rate,D.involucrata provides the best case in conservation of the core eudicot paleogenome.展开更多
The Asiatic hybrid lily cultivar Lilium dazzling(family Liliaceae)is a perennial herbaceous bulbous plant with bright yellow flowers of ornamental values.It also shows resistance to diseases and abiotic stress,making ...The Asiatic hybrid lily cultivar Lilium dazzling(family Liliaceae)is a perennial herbaceous bulbous plant with bright yellow flowers of ornamental values.It also shows resistance to diseases and abiotic stress,making it an ideal parent for breeding studies.This study established a sterile culture system using scales of dazzling lily as explants to induce polyploidy.Adventitious buds growing to 1 cm were treated with different concentrations of colchicine(125,250 and 500μmol·L-1),pendimethalin or trifluralin(100,200 and 300μmol·L-1,respectively)for 12,24 and 36 h.Flow cytometry and chromosome counting were used to identify ploidy,and the phenotype of the polyploids was examined by stomatal observation and leaf index determination.With increasing mutagen concentration and exposure time,the mortality and mutagenic rate increased.The optimal treatment group was:300μmol·L-1 trifluralin for 12 h,which resulted in 15.55%mortality rate and 42.22%induction rate.The polyploid plants showed a significant increase in stomata length,leaf length and leaf width,with a decrease in stomatal density compared with the control plants.This study provided a basis for polyploid breeding.展开更多
According to conventional theory, little genomic changes should occur in homozygous and stable amphiploids of the grass family, particularly those involving polyploid wheat as a parent. In the present study, however, ...According to conventional theory, little genomic changes should occur in homozygous and stable amphiploids of the grass family, particularly those involving polyploid wheat as a parent. In the present study, however, extensive genomic changes were detected in two octoploid partial amphiploids of common wheat (Triticum aestivum L.)_wheatgrass (Agropyron intermedium (Host) P.B.=Elytrigia intermedia (Host) Nevski=Thinopyrum intermedium (Host) Barkworth and Dewey), namely Zhong 3 and Zhong 5, by RFLP analysis using 10 low_copy, wheat chromosome_specific sequences and 33 representative homoeologous group_specific sequences as probes. Genomic changes involved loss of wheat hybridization fragment(s) and/or acquisition of new fragment(s). Uniformity of the RFLP patterns among 5 individual plants taken respectively from Zhong 3 and Zhong 5 in two successive generations, suggested that genomic changes probably had occurred in the early few generations after octoploid amphiploid formation, and remained essentially static thereafter. The highly similar RFLP patterns between Zhong 3 and Zhong 5, which had identical genomic constitution but differed from each other due to involvement of different wheat varieties as parents imply that genomic changes were probably not at random. Possible causes for the extensive and rapid genomic changes in the newly formed plant amphiploids, as well as their implications for polyploid genome evolution and breeding application are discussed.展开更多
Recent work revealed that, in the genomes of polyploid wheat, there exists a class of low_copy and chromosome_specific sequences that are labile upon polyploid formation. This class of sequences was proposed to play ...Recent work revealed that, in the genomes of polyploid wheat, there exists a class of low_copy and chromosome_specific sequences that are labile upon polyploid formation. This class of sequences was proposed to play a critical role in the stabilization and establishment of nascent plant polyploids as new species. To further study this issue, five wheat chromosome 7B_specific sequences, isolated from common wheat (Triticum aestivum L.) by chromosome microdissection, were characterized. The sequences were studied by genomic Southern hybridizations on a collection of polyploid wheats and their diploid progenitors. Four sequences hybridized to all polyploid species, but at the diploid level to only species closely related to the B_genome of polyploid wheat. This indicates that these sequences originated with the divergence of the diploid species, and was then vertically transmitted to polyploids. One sequence hybridized to all species at both the diploid and polyploid levels, suggesting its elimination after the polyploid wheat formation. The hybridization of this sequence to two synthetic polyploid wheats indicated that sequence elimination is a rapid event and probably related to methylation status of the sequence. Based on the above results, we suggest that selective changes of low_copy sequences occur rapidly after polyploid formation, which may contribute to the differentiation of chromosomes in newly formed allopolyploid wheats.展开更多
文摘Polyploidization is one of the most crucial pathways in introducing speciation and broadening biodiversity, especially in the Plant Kingdom. Although the majority of studies have focused only on allopolyploid or disomic polyploids, polysomic polyploid species have occurred frequently in higher plants. Due to the occurrence of the capabilities of more copies of alleles in a locus which can have additive dosage effects and/or allelic interactions, polysomic polyploids can lead to unique gene regulations to silence or adjust the expression level to create variations in organ size, metabolic products, and abiotic stress tolerance and biotic stress resistance, etc. This review aims to comprehensively summarize the contemporary understanding and findings concerning the molecular mechanisms of gene expression as well as gene regulation in natural typed and resynthesized polysomic polyploid plants. The review investigates the molecular level of phenomena in polysomic polyploid plants such as 1) typically enlarging organ size and stabilizing meiosis, 2) increasing phytochemical content and metabolic products, 3) enhancing the ability to adapt with biotic and abiotic stress, and 4) changing in gene regulation to silence or adjust the expression levels involve in sequence elimination, methylation, gene suppression, subfunctionalization, neo-functionalization, and transposon activation.
基金supported by the Tree Breeding Research Project of Zhejiang Province,China(2016C02056-12)。
文摘Most Rhododendron species are ornamental flowering species widely distributed in Asia,North America,and West Europe.Rhododendron fortunei,one of the endemic Rhododendron species in China,has beautiful flowers with bright colors and is being exploited to meet the needs of the flower market.Polyploid plants usually show superiority in growth,disease resistance,and adaption over their diploid relatives.Here,we report the first case of polyploid induction in R.fortunei.In order to induce polyploidy in R.fortunei,germinating seeds were treated with different concentrations of oryzalin for 16 h.By evaluating ploidy level with flow cytometry,a total of 34 polyploid R.fortunei lines,including 27 tetraploid lines and seven octoploid lines,were obtained.A comparison of treatments indicated that 7.5 mg L^-1 oryzalin was the optimal concentration for polyploid induction in seeds of R.fortunei.Compared with diploid plants,tetraploid and octoploid plants exhibited slower growth rates and had thicker and rounder curled leaves with more leaf epidermal hairs.Moreover,larger stomata at lower density were also observed in the leaves of polyploid plants.Chlorophyll contents were also significantly increased in polyploid plants,which leads to a darker green leaf color.Both small and large individuals exhibiting the same characteristics were observed among the obtained tetraploid plants.Overall,our study establishes a feasible method for polyploid induction in R.fortunei,thus providing a basis for breeding new R.fortunei varieties.
基金Supported by the National Natural Science Foundation of China(NSFC31160432)the Key Project of Department of Education,Yunnan Province(2011Z108)~~
文摘[Objective] This study aimed to explore the origin and evolution of poly- poids in Parakmeria Hu et Cheng through LEAFY gene clone and sequence analysis. [Method] In this study, LEAFY gene in Parakmeria species and its relative genera was cloned and sequenced using molecular biology methods. With reference to LEAFY gene sequence published by NCBI, the origin pattern of polypoids in Parakmeria was explored and reasons for the distribution layout of different polypoids were analyzed through sequence alignment and phylogenetic analysis. [Result] Different Magnoliaceae species can be distinguished using the LEAFY gene, and there was a length polymorphism found in the 3＋ end of the LEAFY gene, which can be used to divide Magnoliaceae plants of different species or in different genera, thus of high application value. [Conclusion] Most Parakmeria tetraploids are produced by polyploidization of homologous chromosomes, while Parakmeria hexaploids are chiefly produced by both polyploidization of homologous chromosomes and heterologous hybridization.
基金supported by National Natural Science Foundation of China(32272153)Henan Province Science and Technology R&D Joint Fund(232301420025)+4 种基金National Key Research and Development Program of China(2023YFD1200200)the Key Research Project of the Shennong Laboratory(SN01-2022-03)Independent Innovation Foundation of Henan Academy of Agricultural Sciences(2024ZC024)China Agriculture Research System(CARS-13)Henan Provincial Agriculture Research System(S2012-5).
文摘Wild peanut(Arachis)species are promising sources of disease resistance for improving peanut cultivars.The objective of this study was to assess cross-compatibility among cultivated and wild peanuts in crosses between eight peanut cultivars and 27 wild species carrying the A,B,E,Ex,F,K,P,and H genomes.Embryo culture and chromosome doubling led to polyploids representing hybrids between cultivated peanut and A.stenosperma,A.macedoi,A.duranensis,A.villosa,and A.diogoi.The first two showed greater resistance to bacterial wilt than their cultivated parents.DNA markers were developed for verifying the hybrids and for identifying translocation or introgression lines with alien chromosome fragments.
基金funded by the National Natural Science Foundation of China(grant no.32270238 and 31870311).
文摘Subtropical evergreen broad-leaved trees are usually vulnerable to freezing stress,while hexaploid wild Camellia oleifera shows strong freezing tolerance.As a valuable genetic resource of woody oil crop C.oleifera,wild C.oleifera can serve as a case for studying the molecular bases of adaptive evolution to freezing stress.Here,47 wild C.oleifera from 11 natural distribution sites in China and 4 relative species of C.oleifera were selected for genome sequencing.“Min Temperature of Coldest Month”(BIO6)had the highest comprehensive contribution to wild C.oleifera distribution.The population genetic structure of wild C.oleifera could be divided into two groups:in cold winter(BIO6≤0℃)and warm winter(BIO6>0℃)areas.Wild C.oleifera in cold winter areas might have experienced stronger selection pressures and population bottlenecks with lower N_(e) than those in warm winter areas.155 singlenucleotide polymorphisms(SNPs)were significantly correlated with the key bioclimatic variables(106 SNPs significantly correlated with BIO6).Twenty key SNPs and 15 key copy number variation regions(CNVRs)were found with genotype differentiation>50%between the two groups of wild C.oleifera.Key SNPs in cis-regulatory elements might affect the expression of key genes associated with freezing tolerance,and they were also found within a CNVR suggesting interactions between them.Some key CNVRs in the exon regions were closely related to the differentially expressed genes under freezing stress.The findings suggest that rich SNPs and CNVRs in polyploid trees may contribute to the adaptive evolution to freezing stress.
文摘Hibiscus Linn.,an angiosperm genus belonging to Malvaceae,Malvales,is mainly distributed in tropic and subtropic regions.Numerous species within the Hibiscus genus exhibit large and visually appealing flowers that are highly prized for their ornamental beauty and enjoy widespread admiration.For instance,H.syriacus serves as the national flower of South Korea,H.rosa-sinensis is favored as the floral emblem of Malaysia,and Chengdu city has earned the moniker"City of H.mutabilis"owing to its substantial cultivation.
基金supported by the National Natural Science Foundation of China(32470676 and 32170236)Central Guidance on Local Science and Technology Development Fund of Hebei Province(246Z2508G)+2 种基金Hebei Natural Science Foundation(C2020209064)Tangshan Science and Technology Program Project(21130217C)Key research project of North China University of Science and Technology(ZD-YG-202313-23).
文摘As a high-value eudicot family,many famous horticultural crop genomes have been deciphered in Oleaceae.However,there are currently no bioinformatics platforms focused on empowering genome research in Oleaceae.Herein,we developed the first comprehensive Oleaceae Genome Research Platform(OGRP,https://oleaceae.cgrpoee.top/).In OGRP,70 genomes of 10 Oleaceae species and 46 eudicots and 366 transcriptomes involving 18 Oleaceae plant tissues can be obtained.We built 34 window-operated bioinformatics tools,collected 38 professional practical software programs,and proposed 3 new pipelines,namely ancient polyploidization identification,ancestral karyotype reconstruction,and gene family evolution.Employing these pipelines to reanalyze the Oleaceae genomes,we clarified the polyploidization,reconstructed the ancestral karyotypes,and explored the effects of paleogenome evolution on genes with specific biological regulatory roles.Significantly,we generated a series of comparative genomic resources focusing on the Oleaceae,comprising 108 genomic synteny dot plots,1952225 collinear gene pairs,multiple genome alignments,and imprints of paleochromosome rearrangements.Moreover,in Oleaceae genomes,researchers can efficiently search for 1785987 functional annotations,22584 orthogroups,29582 important trait genes from 74 gene families,12664 transcription factor-related genes,9178872 transposable elements,and all involved regulatory pathways.In addition,we provided downloads and usage instructions for the tools,a species encyclopedia,ecological resources,relevant literatures,and external database links.In short,ORGP integrates rich data resources and powerful analytical tools with the characteristic of continuous updating,which can efficiently empower genome research and agricultural breeding in Oleaceae and other plants.
基金support from the National Natural Science Foundation of China(Grant No.32001995)the Major Science and Technology Project of Henan Province(Grant No.221100110400)+3 种基金the China Agriculture Research System of MOF and MARA(Grant No.CARS-26)the Special Engineering Science and Technology Innovation,CAAS(Grant No.CAAS-ASTIP-2024-ZFRI).Part of this research was funded under the TKI project:“Novel genetic and genomic tools for polyploid crops”(KV 1605-020BO 26.03009004,BO 50002022)and USDA's National Institute of Food and Agriculture(NIFA)Specialty Crop Research Initiative project“Tools for genomics assisted breeding in polyploids:Development of a community resource”(Grant No.2020-51181-32156/SCRI)received a scholarship from China Scholarship Council(Grant No.202303250034).
文摘Fruit quality traits play an important role in consumption of kiwiberry(Actinidia arguta).The genetic basis of fruit quality traits in this woody,perennial and dioecious fruit crop remains largely unknown.This study aimed to identify the underlying genetic basis of fruit quality traits in A.arguta,using a single nucleotide polymorphism(SNP)genetic linkage map previously developed in a tetraploid F1 population of‘Ruby-3’בKuiLv-M’.The F1 population was phenotyped over three years(2020–2022)for fruit quality traits,including skin color,flesh color,fruit weight,fruit diameter,total soluble solids,fruit longitudinal diameter and fruit shape index.A total of nine QTLs were detected for five traits,explaining 10%–32%of the trait variation.For fruit color,the support interval of a major QTL on LG9 contained an MYB transcription factor MYB110,which was previously demonstrated to control color regulation in kiwifruit,thus suggesting that the MYB110 is the candidate gene for fruit color in kiwiberry.The linked marker for fruit color was validated in an F1 population and 25 kiwiberry cultivars.In conclusion,the knowledge obtained through the QTL mapping is applicable to improve the efficiency and cost-effectiveness in kiwiberry breeding.
基金supported by the Sino-German Research Project(GZ 1362)Grains Research and Development Corporation International Visiting Fellowship(UWA2406-010BGX)+1 种基金the National Natural Science Foundation of China(32171982)the Fundamental Research Funds for the Central Universities of the Chinese Government(2662023PY004).
文摘Allopolyploids often exhibit advantages in vigor and adaptability compared to diploids.A long-term goal in the economically important Brassica genus has been to develop a new allohexaploid crop type(AABBCC)by combining different diploid and allotetraploid crop species.However,early-generation allohexaploids often face challenges like unstable meiosis and low fertility,and the phenotypic performance of these synthetic lines has rarely been assessed.This study analyzes agronomic traits,fertility,and genome stability in ArArBcBcCcCc lines derived from four crosses between B.carinata and B.rapa after 9–11 selfing generations.Our results demonstrate polyploid advantage in vigor and seed traits,considerable phenotypic variation,and high fertility and genome stability.Meanwhile,parental genotypes significantly influence outcomes in advanced allohexaploids.Structural variants,largely resulting from A–C homoeologous exchanges,contribute to genomic variation and influence hexaploid genome stability,with the A sub-genome showing the highest variability.Both positive and negative impacts of SVs on fertility and seed weight are observed.Pseudo-euploids,frequently appearing,do not significantly affect fertility or other agronomic traits compared to euploids,indicating a potential pathway toward a stable allohexaploid species.These findings provide insights into the challenge and potential for developing an adaptable and stable Brassica hexaploid through selection.
基金supported by the National Key Resarch and Development Program of China(Grant No.2023YFD1200802)the Base Bank of Lingnan Rice Germplasm Resources Project,China(Grant No.2024B1212060009).
文摘Polyploidization is a commonly employed strategy in crop breeding to augment genetic diversity,particularly leveraging the distinctive benefits of additional progressive heterosis or multi-generation heterosis unique to polyploidy.Despite genetic disparities between polyploids and diploids,challenges stem from reproductive anomalies,complicating genetic investigations in polyploid systems.Through nearly two decades of intensive research,our team has effectively generated a series of fertile tetraploid lines known as neo-tetraploid rice(NTR),facilitating comparative genetic studies between diploid and tetraploid rice.In this study,we identified diploid counterparts(H3d and H8d)for two NTR lines[Huaduo 3(H3)and Huaduo 8(H8)]and utilized them to create diploid and tetraploid fertile F_(2) populations to assess genotype segregation ratios,recombination rates,and their impact on QTL mapping via bulked segregant analysis combined with sequencing(BSA-seq).Additionally,we assessed yield heterosis in F_(1) and F_(2) generations of two tetraploid populations(H3×H8 and T449×H1),revealing evidence of multi-generation heterosis in polyploid rice.These findings provide valuable insights into the advantages and challenges of polyploid rice breeding.
基金This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA08030202 and XDA08030201)the earmarked fund for Modern Agro-industry Technology Research System(NYCYTX-49)the Autonomous Project of the State Key Laboratory of Freshwater Ecology and Biotechnology(2016FBZ01).
文摘Genome polyploidy has been revealed to result in evolutionary advantages and novelties,and therefore,polyploid aquatic animals may possess excellent traits of economic interest including rapid growth,extensive adaptability and disease resistance.For this reason,numerous species of natural polyploid fishes,such as common carp,gibel carp,crucian carp,salmon,and sturgeon,were chosen as important target species for aquaculture.Many artificial polyploids have been commercially utilized for aquaculture and most of them were created from natural polyploid fishes of the Cyprinidae and Salmonidae.Thanks to the easy mass production and better economic traits in growth and flesh quality,the synthetized autopolyploids or allopolyploids from natural polyploid species in cyprinid fishes have been extensively applied to aquaculture throughout China.This review outlines polyploidy advantages and innovative opportunities,lists natural polyploid species used in aquaculture,and summarizes artificial polyploids that have been induced or synthetized,and used in aquaculture.Moreover,some main research trends on polyploid utilization and ploidy manipulation of aquaculture animals are also introduced and discussed in the review.
基金supported by the National Natural Science Foundation of China(NSFC,31970564,32000397,32171982)the Fundamental Research Funds for the Central Universities(2662023PY004)。
文摘"Synthetic"allopolyploids recreated by interspecific hybridization play an important role in providing novel genomic variation for crop improvement.Such synthetic allopolyploids often undergo rapid genomic structural variation(SV).However,how such SV arises,is inherited and fixed,and how it affects important traits,has rarely been comprehensively and quantitively studied in advanced generation synthetic lines.A better understanding of these processes will aid breeders in knowing how to best utilize synthetic allopolyploids in breeding programs.Here,we analyzed three genetic mapping populations(735 DH lines)derived from crosses between advanced synthetic and conventional Brassica napus(rapeseed)lines,using whole-genome sequencing to determine genome composition.We observed high tolerance of large structural variants,particularly toward the telomeres,and preferential selection for balanced homoeologous exchanges(duplication/deletion events between the A and C genomes resulting in retention of gene/chromosome dosage between homoeologous chromosome pairs),including stable events involving whole chromosomes("pseudoeuploidy").Given the experimental design(all three populations shared a common parent),we were able to observe that parental SV was regularly inherited,showed genetic hitchhiking effects on segregation,and was one of the major factors inducing adjacent novel and larger SV.Surprisingly,novel SV occurred at low frequencies with no significant impacts on observed fertility and yield-related traits in the advanced generation synthetic lines.However,incorporating genome-wide SV in linkage mapping explained significantly more genetic variance for traits.Our results provide a framework for detecting and understanding the occurrence and inheritance of genomic SV in breeding programs,and support the use of synthetic parents as an important source of novel trait variation.
基金supported by the Special Funds for Construction of Innovative Provinces in Hunan Province,China(2021NK1007)the Hunan Provincial Innovation Foundation for Postgraduate,China(CX20230779)the Scientific Innovation Fund for Post-graduates of Central South University of Forestry and Technology,China(2023CX01009)。
文摘Plant polyploidy often occurs in conjunction with higher yield and superior quality.Therefore,obtaining polyploid germplasms is a significant part of breeding.The oil-tea Camellia tree is an important native woody plant that produces high-quality edible oil and includes many species of Camellia with different ploidies.However,whether higher ploidy levels in oil-tea Camellia trees are related to better traits remains unclear.In this study,the ploidy levels of 30 different oil-tea Camellia strains in three different species in the Sect.Paracamellia were determined by flow cytometry and chromosome preparation,and the phenotypic characteristics and fatty acid compositions of the fruits were examined by field observations and laboratory analyses.The correlations between the ploidy level of oil-tea Camellia and the main traits of the fruit were investigated.Our results showed that 10 Camellia lanceoleosa strains were diploid,10 Camellia meiocarpa strains were tetraploid and 10 Camellia oleifera strains were hexaploid.Hexaploid C.oleifera had larger fruit size and weight,more seeds per fruit,greater seed weight per fruit,higher oil content and greater yield per crown width than tetraploid C.meiocarpa and diploid C.lanceoleosa,but their fruit peel thickness and fresh seed rate were significantly lower,and these traits were significantly correlated with ploidy level.In addition,in terms of fatty acid composition,hexaploid C.oleifera had a higher oleic acid content than tetraploid C.meiocarpa and diploid C.lanceoleosa,but their linoleic acid,linolenic acid and arachidonic acid contents were lower.The contents of palmitic acid,stearic acid and total unsaturated fatty acids were not significantly correlated with ploidy level.In conclusion,certain correlations exist between the main characteristics of oil-tea Camellia fruit and the ploidy level,and increasing the ploidy level led to an increase in fruit yield with no effect on oil composition.The discovery of variations in the main characteristics of oil-tea Camellia fruit with different ploidies will facilitate germplasm innovation and lay a foundation for ploidy breeding and mechanistic research on fruit traits.
基金This work was financially supported by the National Key Research and Development Program of China(Grant No.2022YFF1002900 and 2020YFE0202900)the National Natural Science Foundation of China(32270576)+4 种基金Jiangsu Provincial Key Research and Development Program(BE2022346)Seed Industry Revitalization Project of Jiangsu Province(JBGS[2021]006 and JBGS[2021]013)the Jiangsu Agricultural Technology System(JATS[2023]422)the Joint Research of Wheat Variety Improvement of AnhuiZhongshan Biological Breeding Laboratory(ZSBBL)(ZSBBL-KY2023-02-2)。
文摘Polyploidization in plants often leads to increased cell size and grain size,which may be affected by the increased genome dosage and transcription abundance.The synthesized Triticum durum(AABB)-Hay-naldia villosa(WM)amphiploid(AABBM)has significantly increased grain size,especially grain length,than the tetraploid and diploid parents.To investigate how polyploidization affects grain development at the transcriptional level,we perform transcriptome analysis using the immature seeds of T.durum,H.villosa,and the amphiploid.The dosage effect genes are contributed more by differentially expressed genes from genome V of H.villosa.The dosage effect genes overrepresent grain development-related genes.Inter-estingly,the vernalization gene TaVRN1 is among the positive dosage effect genes in the T.durum-H.villosa and T.turgidum-Ae.tauschii amphiploids.The expression levels of TaVRN1 homologs are positively correlated with the grain size and weight.The TaVRN1-B1 or TaVRN1-D1 mutation shows delayed florescence,decreased cell size,grain size,and grain yield.These data indicate that dosage effect genes could be one of the important explanations for increased grain size by regulating grain development.The identification and functional validation of dosage effect genes may facilitate the finding of valuable genes for improvingwheat yield.
基金funded by the National Natural Science Foundation of China(Grant Nos.32170236 and 31501333)the Natural Science Foundation of Hebei Province(Grant No.C2020209064)the Youth Foundation of Educational Committee of Hebei Province(Grant No.QN2020139)。
文摘Coptis chinensis Franch.,also named Chinese goldthread is a member of Ranunculaceae in the order Ranunculales and represents an important lineage of early eudicots with traditional medicinal value.In our study,by using syntenic analysis combined with phylogenomic analysis of C.chinensis and four other representative genomes from basal and core eudicots,we confirmed that the WGD event in C.chinensis was shared by Aquilegia coerulea and Papaver somniferum L.and quickly occurred after Ranunculales diverged from other eudicots,likely a Ranunculales common tetraploidization(RCT).The synonymous nucleotide substitutions at synonymous sites distribution of syntenic blocks across these genomes showed that the evolutionary rate of the P.somniferum genome is faster than that of the C.chinensis genome by approximately 13.7%,possibly due to Papaveraceaes having an additional special tetraploidization event(PST).After Ks correction,the RCT dated to 115—130 million years ago(MYA),which was close to the divergence of Ranunculaceaes and Papaveraceaes approximately115.45—130.51 MYA.Moreover,we identified homologous genes related to polyploidization and speciation and constructed multiple sequence alignments with different reference genomes.Notably,the event-related subgenomes in the basal genomes all showed genomic fractionation bias,suggesting a likely allopolyploid nature of the RCT,PST and T-Alpha and T-Beta events in Tetracentron sinense.In addition,we detected that the sixteen P450 subfamilies were markedly expanded in the genomes of Ranunculales,and most of them were related to the RCT and PST events.We constructed a new platform for Early Eudicot Comparative Genomic Research(http://www.cgrpoee.top/index.html)to store more information.In summary,our findings support the WGD of C.chinensis shared by Ranunculales,which is likely an allotetraploidization event.This present effort offered new insights into the evolution of key polyploidization events and the genes related to secondary metabolites during the diversification of early eudicots.
基金supported by the National Natural Science Foundation of China(Grant Nos.32170236,31501333,and 32000405)Natural Science Foundation of Hebei Province(Grant No.C2020209064)the Innovation and Entrepreneurship Training Program for College Students of North China University of Science and Technology(Grant No.X2019252)。
文摘Scientific knowledge about the ancestral genome of core eudicot plant kingdom can potentially have profound impacts on both basic and applied research,including evolution,genetics,genomics,ecology,agriculture,forestry,and global climate.To investigate which plant conserves best the core eudicots common ancestor genome,we compared Arcto-Tertiary relict Nyssaceae and 30 other eudicot plant families.The genomes of Davidia involucrata(a known living fossil),Camptotheca acuminata and Nyssa sinensis,one per existent genus of Nyssaceae,were performed comparative genomic analysis.We found that Nyssaceae originated from a single Nyssaceae common tetraploidization event(NCT)-autotetraploidization 28-31 Mya after the core eudicot common hexaploidization(ECH).We identified Nyssaceae orthologous and paralogous genes,determined its chromosomal evolutionary trajectory,and reconstructed the Nyssaceae most recent ancestor genome.D.involucrata genome contained the entire seven paleochromosomes and 17 ECH-generated eudicot common ancestor chromosomes and was the slowest in mutation among the analyzed 42 species of 31 plant families.Combing both its high retention of paleochromosomes and its low mutation rate,D.involucrata provides the best case in conservation of the core eudicot paleogenome.
文摘The Asiatic hybrid lily cultivar Lilium dazzling(family Liliaceae)is a perennial herbaceous bulbous plant with bright yellow flowers of ornamental values.It also shows resistance to diseases and abiotic stress,making it an ideal parent for breeding studies.This study established a sterile culture system using scales of dazzling lily as explants to induce polyploidy.Adventitious buds growing to 1 cm were treated with different concentrations of colchicine(125,250 and 500μmol·L-1),pendimethalin or trifluralin(100,200 and 300μmol·L-1,respectively)for 12,24 and 36 h.Flow cytometry and chromosome counting were used to identify ploidy,and the phenotype of the polyploids was examined by stomatal observation and leaf index determination.With increasing mutagen concentration and exposure time,the mortality and mutagenic rate increased.The optimal treatment group was:300μmol·L-1 trifluralin for 12 h,which resulted in 15.55%mortality rate and 42.22%induction rate.The polyploid plants showed a significant increase in stomata length,leaf length and leaf width,with a decrease in stomatal density compared with the control plants.This study provided a basis for polyploid breeding.
文摘According to conventional theory, little genomic changes should occur in homozygous and stable amphiploids of the grass family, particularly those involving polyploid wheat as a parent. In the present study, however, extensive genomic changes were detected in two octoploid partial amphiploids of common wheat (Triticum aestivum L.)_wheatgrass (Agropyron intermedium (Host) P.B.=Elytrigia intermedia (Host) Nevski=Thinopyrum intermedium (Host) Barkworth and Dewey), namely Zhong 3 and Zhong 5, by RFLP analysis using 10 low_copy, wheat chromosome_specific sequences and 33 representative homoeologous group_specific sequences as probes. Genomic changes involved loss of wheat hybridization fragment(s) and/or acquisition of new fragment(s). Uniformity of the RFLP patterns among 5 individual plants taken respectively from Zhong 3 and Zhong 5 in two successive generations, suggested that genomic changes probably had occurred in the early few generations after octoploid amphiploid formation, and remained essentially static thereafter. The highly similar RFLP patterns between Zhong 3 and Zhong 5, which had identical genomic constitution but differed from each other due to involvement of different wheat varieties as parents imply that genomic changes were probably not at random. Possible causes for the extensive and rapid genomic changes in the newly formed plant amphiploids, as well as their implications for polyploid genome evolution and breeding application are discussed.
文摘Recent work revealed that, in the genomes of polyploid wheat, there exists a class of low_copy and chromosome_specific sequences that are labile upon polyploid formation. This class of sequences was proposed to play a critical role in the stabilization and establishment of nascent plant polyploids as new species. To further study this issue, five wheat chromosome 7B_specific sequences, isolated from common wheat (Triticum aestivum L.) by chromosome microdissection, were characterized. The sequences were studied by genomic Southern hybridizations on a collection of polyploid wheats and their diploid progenitors. Four sequences hybridized to all polyploid species, but at the diploid level to only species closely related to the B_genome of polyploid wheat. This indicates that these sequences originated with the divergence of the diploid species, and was then vertically transmitted to polyploids. One sequence hybridized to all species at both the diploid and polyploid levels, suggesting its elimination after the polyploid wheat formation. The hybridization of this sequence to two synthetic polyploid wheats indicated that sequence elimination is a rapid event and probably related to methylation status of the sequence. Based on the above results, we suggest that selective changes of low_copy sequences occur rapidly after polyploid formation, which may contribute to the differentiation of chromosomes in newly formed allopolyploid wheats.
