All plant organs are derived from stem cell-containing meristems.In maize,the shoot apical meristem(SAM)is responsible for generating all above-ground structures,including the male and female inflorescence meristems(I...All plant organs are derived from stem cell-containing meristems.In maize,the shoot apical meristem(SAM)is responsible for generating all above-ground structures,including the male and female inflorescence meristems(IMs),which give rise to tassel and ear,respectively.Forward and reverse genetic studies on maize meristem mutants have driven forward our fundamental understanding of meristem maintenance and differentiation mechanisms.However,the high genetic redundancy of the maize genome has impeded progress in functional genomics.This review comprehensively summarizes recent advancements in understanding maize meristem development,with a focus on the integration of single-cell and spatial technologies.We discuss the mechanisms governing stem cell maintenance and differentiation in SAM and IM,emphasizing the roles of gene regulatory networks,hormonal pathways,and cellular omics insights into stress responses and adaptation.Future directions include cross-species comparisons,multi-omics integration,and the application of these technologies to precision breeding and stress adaptation research,with the ultimate goal of translating our understanding of meristem into the development of higher yield varieties.展开更多
Shoot meristems used for the study were exercised from the in vitro regenerated shoots cultured on MS medium supplemented with 0.5 mg/L of BAP for multiplication. The sensitivity of the in vitro regenerated was studie...Shoot meristems used for the study were exercised from the in vitro regenerated shoots cultured on MS medium supplemented with 0.5 mg/L of BAP for multiplication. The sensitivity of the in vitro regenerated was studied using shoot meristems of 0.5 cm. Shoot meristems were cultured on medium containing 10-100 mg/l kanamycin to determine the concentration that was lethal for multiple shoot induction and root induction. The response of shoot multiplication decreased (66.2%-6.2%) as the concentration of kanamycin increased (10.0-70.0 mg/L) with complete inhibition of shoot proliferation at 100 mg/L kanamycin. The rooting phase was very sensitive to kanamycin compared to shoot multiplication. The percentage of shoots that rooted decreased (53.8%-4.8%) with increase in the concentration of kanamycin (10.0-70.0 mg/l) on IBA and 2,4-D supplemented medium. For transformation studies, the shoot tips that were infected with Agrobacterium strain were placed on selection medium containing MS medium with 0.5 mg/L BAP and 100 mg/L kanamycin and scored for the putative transformed shoots. An average of 62.2% of shoot tips developed shoot buds from the base and the shoots reached a length of 0.5-1.0 cm at the end of 30 days of culture on the selective medium in comparison to control which showed no response. An average of 66.7% of the regenerated plants showed GUS expression on selection medium where 43.2% and 65% of GUS expression was recorded in the leaves and callus. Leaves and callus induced from the controls did not show GUS activity. Stable integration of nptII gene with the genomic DNA from these transformed plants was confirmed through PCR analysis. Our result presents an efficient regeneration system using in vitro derived shoot meristems for Agrobacterium mediated gene transfer.展开更多
The maize tassel represents an indeterminate male inflorescence. The number of primordia that a given inflorescence meristem produces is related to its determinacy, i.e., capacity for continued meristem activity.Trans...The maize tassel represents an indeterminate male inflorescence. The number of primordia that a given inflorescence meristem produces is related to its determinacy, i.e., capacity for continued meristem activity.Transcription factors(TFs) controlling determinacy in tassel axillary meristems are well studied in maize, and small RNAs are known to influence tassel development by repressing targets, including tassel-related TFs. As core components of the RNA-inducible silence complex(RISC),Argonaute(AGO) proteins are required for small RNAmediated repression. Here, we characterized the biological function of AGO8b, a tassel-enriched AGO. The abundance of AGO8b transcripts gradually increased during tassel development from inception to gametogenesis and were enriched in the inflorescence meristem and axillary meristems of the tassel. Repressing AGO8b expression resulted in more spikelets, which contributed to a longer central spike of the tassel. Additionally, the transcripts of several HD-ZIP Ⅲ TFs that were canonical targets of micro RNA66(miR66) accumulated in the AGO8b repressed lines. We propose that AGO8b is a negative regulator of the determinacy of inflorescence and axillary meristems, and that it acts by interacting with the miR66-HD-ZIP Ⅲ TF regulatory pathway.展开更多
Despite the presence of about 21%O2 in the atmosphere,organs of plants and mammals are inevitably subject to lower O2 tensions(pO2)due to high O2 demand in metabolic active cells and limited O2 transport efficiency.In...Despite the presence of about 21%O2 in the atmosphere,organs of plants and mammals are inevitably subject to lower O2 tensions(pO2)due to high O2 demand in metabolic active cells and limited O2 transport efficiency.In humans,for example,the p O2 decreases from the ambient 21%(160 mm Hg)of the inhaled air to 2%-9%in the internal organs(Brahimi-Horn and Pouyssegur,2007).To cope with this limited oxygen supply,aerobic organisms have developed a variety of adaptive responses at cellular,tissue,and organismal levels(Bailey-Serres et al.,2012).Although low O2 tensions are the normal conditions for organs,the ambient 21%O2 is usually referred to as normoxia and the lower internal concentrations as hypoxia(van Dongen and Licausi,2015).展开更多
Stem cells in plants,established during embry-ogenesis,are located in the centers of the shoot apical meristem(SAM)and the root apical meristem(RAM).Stem cells in SAM have a capacity to renew themselves and to produce...Stem cells in plants,established during embry-ogenesis,are located in the centers of the shoot apical meristem(SAM)and the root apical meristem(RAM).Stem cells in SAM have a capacity to renew themselves and to produce new organs and tissues indefinitely.Although fully differentiated organs such as leaves do not contain stem cells,cells in such organs do have the capacity to re-establish new stem cells,especially under the induction of phytohormones in vitro.Cytokinin and auxin are critical in creating position signals in the SAM to maintain the stem cell organizing center and to position the new organ primordia,respectively.This review addresses the distinct features of plant stem cells and focuses on how stem cell renewal and differentiation are regulated in SAMs.展开更多
As a cell cycle regulator, the Myb-related CDC5 protein was reported to be essential for the G2 phase of the cell cycle in yeast and animals, but little is known about its function in plants. Here we report the functi...As a cell cycle regulator, the Myb-related CDC5 protein was reported to be essential for the G2 phase of the cell cycle in yeast and animals, but little is known about its function in plants. Here we report the functional characterization of the CDC5 gene in Arabidopsis thaliana. Arabidopsis CDC5 （AtCDC5） is mainly expressed in tissues with high cell division activity, and is expressed throughout the entire process of embryo formation. The AtCDC5 loss-of-function mutant is embryonic lethal. In order to investigate the function of AtCDC5 in vivo, we generated AtCDC5-RNAi plants in which the expression of AtCDC5 was reduced by RNA interference. We found that the G2 to M （G2/M） phase transition was affected in the AtCDC5-RNAi plants, and that endoreduplication was increased. Additionally, the maintenance of shoot apical meristem （SAM） function was disturbed in the AtCDC5-RNAi plants, in which both the WUSCHEL （WUS）- CLAVATA （CLV） and the SHOOT MERISTEMLESS （STM） pathways were impaired. In situ hybridization analysis showed that the expression of STMwas greatly reduced in the shoot apical cells of the AtCDC5-RNAi plants. Moreover, cyclinB1 or Histone4 was found to be expressed in some of these cells when the transcript of STM was undetectable. These results suggest that AtCDC5 is essential for the G2/M phase transition and may regulate the function of SAM by controlling the expression ofSTMand WUS.展开更多
In recent years,some super hybrid rice varieties were bred with strong culms and large panicles,which are mainly contributed by the ipa1-2D locus.A gain-of-function allele of OsSPL14 is the ipa1-2D and it can greatly ...In recent years,some super hybrid rice varieties were bred with strong culms and large panicles,which are mainly contributed by the ipa1-2D locus.A gain-of-function allele of OsSPL14 is the ipa1-2D and it can greatly increase the panicle primary branch number.However,the key downstream genes mediating this trait variation are not fully explored.In this study,we developed high-quality near-isogenic lines(NILs)with a difference of only 30 kb chromosomal segment covering the ipa1-2D locus.Using the NILs,we explored the impact of ipa1-2D on five sequential stages of early inflorescence development,and found that the locus can greatly enhance the initiation of primary branch meristems.A transcriptomic analysis was performed to unveil the downstream molecular network of ipa1-2D,and 87 genes were found differentially expressed,many of which are involved in metabolism and catalysis processes.In addition,transgenic lines of overexpression and RNA interference were generated to shape different levels of OsSPL14.They were also used to validate the expression variation explored by transcriptome.Based on the gene annotation,twelve potential downstream targets of ipa1-2D were selected,and their expression variation was confirmed by qRT-PCR analysis both in NILs and transgenic lines.This research expands the molecular network underlying ipa1-2D and provides novel gene information which might be involved in the control of panicle branching.We discussed the potential function of identified genes and highlighted their values for future function exploration and breeding application.展开更多
In wheat plants at the vegetative growth stage, the shoot apical meristem (SAM) produces leaf primordia. When reproductive growth is initiated, the SAM forms an inflorescence meristem (IM) that differentiates a series...In wheat plants at the vegetative growth stage, the shoot apical meristem (SAM) produces leaf primordia. When reproductive growth is initiated, the SAM forms an inflorescence meristem (IM) that differentiates a series of spikelet meristem (SM) as the branch. The SM then produces a series of floret meristem (FM) as the branch. To identify the mechanisms that regulate formation of the reproductive meristems in wheat, we have investigated a leaf initiation mutant, fushi-darake (fdk) which was developed by ion beam mutagenesis. The morphological traits were compared in wild type (WT) and fdk mutant plants grown in the experimental field. WT plants initiated leaves from SAM at regular intervals in spiral phyllotaxy, while fdk plants had 1/2 alternate phyllotaxy with rapid leaf emergence. The fdk plants have increased numbers of nodes and leaves compared with WT plants. The time interval between successive leaf initiation events (plastochron) was measured in plants grown in a growth chamber. The fdk plants clearly show the rapid leaf emergence, indicating a shortened plastochron. Each tiller in fdk plants branches at the upper part of the culm. The fine structure of organ formation in meristems of fdk plants was examined by scanning electron microscopy (SEM). The SEM analysis indicated that fdk plants show transformation of spikelet meristems into vegetative shoot meristems. In conclusion, the fdk mutant has a heterochronic nature, i.e., both reproductive and vegetative programs were simultaneously in operation during the reproductive phase, resulting in a shortened plastochron and transformation of reproductive spikelets into vegetative shoots.展开更多
In the present research, we have investigated morphologicaltraits of different organs of Arabidopsis species in Iran. Trichomes on the aerial parts of three species were studied under anatomical microscopy. The specie...In the present research, we have investigated morphologicaltraits of different organs of Arabidopsis species in Iran. Trichomes on the aerial parts of three species were studied under anatomical microscopy. The species exist in Iran include: Arabidopsis thaliana (Heynh), Arabidopsis pumila (steph) and Arabidopsis wallichii (Hook & thomas). The form of trichomes, basal and stemleaves, fruit length, the attitude of fruit, the existence of trichomes on the fruit, and the color ofpetal are morphological traits which separate the species. Anatomical traits of the leaf and stem of studied species were analyzed using an optical microscope. In the stem, some traits such as the shape of stem in transverse incision, the thickness of skin, the existence of supporting tissue around phloem, the number of xylem and phloem and the wavy form of stele were distinct in the three species. In the leaf, some traits such as the shape of leaf, the number of palisade parenchyma layers, the uniformity of mesophyll tissue, and the density of trichomes were different in the three species. No significant difference has been observed in the study of reproductive meristem, except in A. wallichii. The only difference was related to the size of reproductive meristem of two species and the number of flowers produced from the meristems.展开更多
Although AGAMOUS-LIKE6 (AGL6) MADS-box genes are ancient with wide distributions in gymnosperms and angiosperms, their functions remain poorly understood. Here, we show the biological role of the AGL6-1ike gene, OsMAD...Although AGAMOUS-LIKE6 (AGL6) MADS-box genes are ancient with wide distributions in gymnosperms and angiosperms, their functions remain poorly understood. Here, we show the biological role of the AGL6-1ike gene, OsMADS6, in specifying floral organ and meristem identities in rice (Oryza sativa L.). OsMADS6 was strongly ex- pressed in the floral meristem at early stages. Subsequently, OsMADS6 transcripts were mainly detectable in paleas, lodicules, carpels and the integument of ovule, as well as in the receptacle. Compared to wild type plants, osmads6 mutants displayed altered palea identity, extra glume-like or mosaic organs, abnormal carpel development and loss of floral meristem determinacy. Strikingly, mutation of a SEPALLATA (SEP)-like gene, OsMADS1 (LHS1), enhanced the defect of osmads6 flowers, and no inner floral organs or glume-like structures were observed in whorls 2 and 3 of osmadsl-z osmads6-1 flowers. Furthermore, the osmadsl-z osmads6-1 double mutants developed severely indetermi- nate floral meristems. Our finding, therefore, suggests that the ancient OsMADS6 gene is able to specify "floral state" by determining floral organ and meristem identities in monocot crop rice together with OsMADS1.展开更多
The homeobox transcription factor WUSCHEL(WUS)plays a critical role in keeping the balance between the maintenance and differentiation of stem cell population in shoot and floral meristems of Arabidopsis thaliana.The ...The homeobox transcription factor WUSCHEL(WUS)plays a critical role in keeping the balance between the maintenance and differentiation of stem cell population in shoot and floral meristems of Arabidopsis thaliana.The corresponding gene SlWUS is yet to be characterized in tomato.In order to characterize SlWUS gene and its biological function,we cloned it from tomato and analyzed its structure.Tissue expression showed that the SlWUS highly expressed in tomato flower abscission zone.The overexpression of SlWUS in Arabidopsis could trigger undifferentiation of plant flower organ and indeterminacy of flower identity,suggesting that SlWUS maybe involved in flower structure development as well as flower organ identity.Taken together,our results indicated that the SlWUS plays an important role in flower abscission zone and plant organ shedding.展开更多
The homologous genes FLORICAULA (FLO) in Antirrhinum and LEAFY (LFY) in Arabidopsis are known to regu- late the initiation of flowering in these two distantly related plant species. These genes are necessary also for ...The homologous genes FLORICAULA (FLO) in Antirrhinum and LEAFY (LFY) in Arabidopsis are known to regu- late the initiation of flowering in these two distantly related plant species. These genes are necessary also for the expression of downstream genes that control floral organ identity. We used Arabidopsis LFY cDNA as a probe to clone and sequence a papaya ortholog of LFY, PFL. It encodes a protein that shares 61% identity with the Arabidopsis LFY gene and 71% identity with the LFY homologs of the two woody tree species: California sycamore (Platanus racemosa) and black cottonwood (Populus trichocarpa). Despite the high sequence similarity within two conserved regions, the N-terminal proline-rich motif in papaya PFL differs from other members in the family. This difference may not affect the gene function of papaya PFL, since an equally divergent but a functional LFY ortholog NEEDLY of Pinus radiata has been reported. Genomic and BAC Southern analyses indicated that there is only one copy of PFL in the papaya genome. In situ hybridization experiments demonstrated that PFL is expressed at a relatively low level in leaf primordia, but it is expressed at a high level in the floral meristem. Quantitative PCR analyses revealed that PFL was expressed in flower buds of all three sex types - male, female, and hermaphrodite with marginal difference between hermaphrodite and unisexual flowers. These data suggest that PFL may play a similar role as LFY in flower development and has limited effect on sex differentiation in papaya.展开更多
In rice,the spikelet is the basic unit of inflorescence,and its development is important for determining the grain yield and quality.We reported a rice spikelet mutant multi-floret spikelet 4(mfs4)which resulted in th...In rice,the spikelet is the basic unit of inflorescence,and its development is important for determining the grain yield and quality.We reported a rice spikelet mutant multi-floret spikelet 4(mfs4)which resulted in the production of extra floral organs or a whole extra floret,and elongated sterile lemmas.The results suggested that the mutation of the MFS4 gene interfered with spikelet meristem determinacy and floral organ identity.In addition,the plant height and the grain length and width in the mfs4 mutant were all less than those in the wild type.Using the bulked segregant analysis method,the MFS4 gene was localized in a 557-kb region on the long arm of chromosome 1.Sequence analysis showed that there was a C-base deletion at the open reading frame of LOC_Os01g67430.Further tests indicated that a wild type copy of LOC_Os01g67430 was able to reverse the mfs4 defects,which indicated that LOC_Os01g67430 was the MFS4 gene.The MFS4 gene encodes a lipase located in the mitochondria and is expressed strongly in the young inflorescence.qRT-PCR results showed that the expression of some genes that were known to regulate spikelet meristem determinacy and grain size were decreased in the mfs4 mutant,which indicated that the MFS4 gene regulates spikelet meristem determinacy and grain size by modulating the expression of these genes.展开更多
It is vital to determine the effective photoperiods of maize for making full use of tropical germplasm, which is the foundation for determining the effect of latitude and planting date on the development of photoperio...It is vital to determine the effective photoperiods of maize for making full use of tropical germplasm, which is the foundation for determining the effect of latitude and planting date on the development of photoperiod-sensitive maize cultivars. The objective of this study is to determine the photoperiod-sensitive inductive phase using reciprocal transfer between long- day （LD） （15 h d^-1） and short-day conditions （SD） （9 h d^-1）. For Huangzao 4 and CML288, days to tassel and pollen shedding were recorded, and stem apical meristems （SAM） were observed by a laser scanning confocal microscope. The results show that the seedlings are insensitive to photoperiod when they are very young （juvenile）. However, after this period, LD delays flowering and increases the leaf numbers below the inflorescence, and the length of the interval of the photoperiod-sensitive inductive phase is longer under LD conditions than under SD conditions. Transferred from SD to LD, plants show a sudden decrease in leaf numbers once sufficient SD has been received for flower commitment. While transferred from LD to SD, plants have a continuous increase in leaf numbers during the photoperiod sensitive inductive phase under LD conditions. At the same time, when plants are competent to flowers, the obvious morphology is the elongation of maize SAM. There is an obvious variance of the photoperiod sensitive phase under LD and SD conditions in different maize.展开更多
Increasing tiller number is a target of high-yield rice breeding. Identification of tiller-defect mutants and their corresponding genes is helpful for clarifying the molecular mechanism of rice tillering. Summarizing ...Increasing tiller number is a target of high-yield rice breeding. Identification of tiller-defect mutants and their corresponding genes is helpful for clarifying the molecular mechanism of rice tillering. Summarizing research progress on the two processes of rice tiller formation, namely the formation and growth of axillary meristem, this paper reviews the effects of genetic factors, endogenous hormones, and exogenous environment on rice tillering, finding that multiple molecular mechanisms and signal pathways regulating rice tillering cooperate rice tillering, and discusses future research objectives and application of its regulatory mechanism. Elucidation of theis mechanism will be helpful for breeding high-yielding rice cultivars with ideal plant type via molecular design breeding.展开更多
Heat therapy followed by the isolation and in vitro culture of apical meristems is a suitable procedure for virus eradication. However, the period of heat treatment is usually long (28 - 50 days) and the yield of viab...Heat therapy followed by the isolation and in vitro culture of apical meristems is a suitable procedure for virus eradication. However, the period of heat treatment is usually long (28 - 50 days) and the yield of viable plants free of viruses after treatment is often low (<50%). Here, we describe an alternative method to obtain virus-free plants. We used traditional Galician cultivars, six apple trees and two pear trees, infected with Apple chlorotic leaf spot virus (ACLSV) and Apple mosaic virus (ApMV). We combined heat therapy of in vitro shoots using a temperature gradient from 25℃to 40℃increasing 1℃per day for a shorter period of time (18 days) with the posterior isolation and culture of apical meristems. All DNA samples analyzed, obtained from plants developed from meristems, were 100% free of ApMV and almost 90% free of ACLSV. With this in vitro procedure combined we obtained a good yield of tested plants free of viruses. Our method is fast and effective and it could be also useful to eradicate these and other viruses in other fruit trees.展开更多
A rice mutant with Yaponica 9522 cultivar background Oryza sativa extraordinary glume 1 （Oseg 1） was identified from the M2 mutant pool mutagenized by ^60Co γ-ray. Compared with wild type plants, Oseg 1 developed l...A rice mutant with Yaponica 9522 cultivar background Oryza sativa extraordinary glume 1 （Oseg 1） was identified from the M2 mutant pool mutagenized by ^60Co γ-ray. Compared with wild type plants, Oseg 1 developed longer empty glumes and rudimentary glumes. In some Oseg 1 mutants, the number of stamens of flowers was reduced and leaf-like lodicules occurred, and excessive lemma/palea-like organ could be observed in some mutant spikelets. This indicated that OsEG1 could regulate the development of rudimentary glumes, empty glumes, lemma/palea, lodicules, and stamens. Genetic analysis indicated that Oseg 1 came from a single recessive genetic locus. To clone OsEG1 gene, F2 population was constructed by a cross between Oseg 1 （Japonica） and Guangluai4 （Indica）. Using map-based cloning approach, OsEG1 was mapped on chromosome 4, between INDEL marker OS407 and WHM0466 with genetic distance of 2.0 cm and 1.0 cm, respectively. These results are useful for further cloning and functional analysis of the OsEG1 gene.展开更多
The shape of an inflorescence varies among cereals,ranging from a highly branched panicle in rice to a much more compact spike in barley(Hordeum vulgare L.)and wheat(Triticum aestivum L.).However,little is known about...The shape of an inflorescence varies among cereals,ranging from a highly branched panicle in rice to a much more compact spike in barley(Hordeum vulgare L.)and wheat(Triticum aestivum L.).However,little is known about the molecular basis of cereal inflorescence architecture.We profiled transcriptomes at three developmental stages of the barley main shoot apex—spikelet initiation,floral organ differentiation,and floral organ growth—and compared them with those from vegetative seedling tissue.Transcript analyses identified 3688 genes differentially transcribed between the three meristem stages,with a further 1394 genes preferentially expressed in reproductive compared with vegetative tissue.Coexpression assembly and Gene Ontology analysis classified these 4888 genes into 28 clusters,revealing distinct patterns for genes such as transcription factors,histone modification,and cell-cycle progression specific for each stage of inflorescence development.We also compared expression patterns of VRS(SIX-ROWED SPIKE)genes and auxin-,gibberellic acid-and cytokinin-associated genes between two-rowed and six-rowed barley to describe regulators of lateral spikelet fertility.Our findings reveal barley inflorescence phase-specific gene expression,identify new candidate genes that regulate barley meristem activities and flower development,and provide a new genetic resource for further dissection of the molecular mechanisms of spike development.展开更多
Background:Manual topping is a routine agronomic practice for balancing the vegetative and reproductive growth of cotton(Gossypium hirsutum)in China,but its cost-effectiveness has decreased over time.Therefore,there i...Background:Manual topping is a routine agronomic practice for balancing the vegetative and reproductive growth of cotton(Gossypium hirsutum)in China,but its cost-effectiveness has decreased over time.Therefore,there is an urgent need to replace manual topping with new approaches,such as biological topping.In this study,we examined the function of Gh REV transcription factors(a classⅢhomeodomain-leucine zipper family,HD-ZIPⅢ)in regulating the development of shoot apical meristem(SAM)in cotton with the purpose of providing candidate genes for biological topping of cotton in the future.Results:We cloned four orthologous genes of At REV in cotton,namely Gh REV1,Gh REV2,Gh REV3,and Gh REV4.All the Gh REVs expressed in roots,stem,leaves,and SAM.Compared with Gh REV1 and Gh REV3,the expression level of Gh REV2 and Gh REV4 was higher in the SAM.However,only Gh REV2 had transcriptional activity.Gh REV2 is localized in the nucleus;and silencing it via virus-induced gene silencing(VIGS)produced an abnormal SAM.Two key genes,Gh WUSA10 and Gh STM,which involved in regulating the development of plant SAM,showed about 50%reduction in their transcripts in VIGS-Gh REV2 plants.Conclusion:Gh REV2 positively regulates the development of cotton SAM by regulating Gh WUSA10 and Gh STM potentially.展开更多
基金supported by Natural Science Foundation of Shandong Province(ZR2023JQ012)the National Natural Science Foundation of China(32101741)+1 种基金National Key Research and Development Program of China(2022YFD1201802)the Taishan Scholar Program of Shandong Provincial Government to F.X.,and National Natural Science Foundation of China(32201694 and U22A20460)to X.H.
文摘All plant organs are derived from stem cell-containing meristems.In maize,the shoot apical meristem(SAM)is responsible for generating all above-ground structures,including the male and female inflorescence meristems(IMs),which give rise to tassel and ear,respectively.Forward and reverse genetic studies on maize meristem mutants have driven forward our fundamental understanding of meristem maintenance and differentiation mechanisms.However,the high genetic redundancy of the maize genome has impeded progress in functional genomics.This review comprehensively summarizes recent advancements in understanding maize meristem development,with a focus on the integration of single-cell and spatial technologies.We discuss the mechanisms governing stem cell maintenance and differentiation in SAM and IM,emphasizing the roles of gene regulatory networks,hormonal pathways,and cellular omics insights into stress responses and adaptation.Future directions include cross-species comparisons,multi-omics integration,and the application of these technologies to precision breeding and stress adaptation research,with the ultimate goal of translating our understanding of meristem into the development of higher yield varieties.
文摘Shoot meristems used for the study were exercised from the in vitro regenerated shoots cultured on MS medium supplemented with 0.5 mg/L of BAP for multiplication. The sensitivity of the in vitro regenerated was studied using shoot meristems of 0.5 cm. Shoot meristems were cultured on medium containing 10-100 mg/l kanamycin to determine the concentration that was lethal for multiple shoot induction and root induction. The response of shoot multiplication decreased (66.2%-6.2%) as the concentration of kanamycin increased (10.0-70.0 mg/L) with complete inhibition of shoot proliferation at 100 mg/L kanamycin. The rooting phase was very sensitive to kanamycin compared to shoot multiplication. The percentage of shoots that rooted decreased (53.8%-4.8%) with increase in the concentration of kanamycin (10.0-70.0 mg/l) on IBA and 2,4-D supplemented medium. For transformation studies, the shoot tips that were infected with Agrobacterium strain were placed on selection medium containing MS medium with 0.5 mg/L BAP and 100 mg/L kanamycin and scored for the putative transformed shoots. An average of 62.2% of shoot tips developed shoot buds from the base and the shoots reached a length of 0.5-1.0 cm at the end of 30 days of culture on the selective medium in comparison to control which showed no response. An average of 66.7% of the regenerated plants showed GUS expression on selection medium where 43.2% and 65% of GUS expression was recorded in the leaves and callus. Leaves and callus induced from the controls did not show GUS activity. Stable integration of nptII gene with the genomic DNA from these transformed plants was confirmed through PCR analysis. Our result presents an efficient regeneration system using in vitro derived shoot meristems for Agrobacterium mediated gene transfer.
基金supported by the National Natural Science Foundation of China (91635303, 31501320) (www.nsfc.gov.cn)National Basic Research Program of China (2014CB138203) (www.most.gov.cn)
文摘The maize tassel represents an indeterminate male inflorescence. The number of primordia that a given inflorescence meristem produces is related to its determinacy, i.e., capacity for continued meristem activity.Transcription factors(TFs) controlling determinacy in tassel axillary meristems are well studied in maize, and small RNAs are known to influence tassel development by repressing targets, including tassel-related TFs. As core components of the RNA-inducible silence complex(RISC),Argonaute(AGO) proteins are required for small RNAmediated repression. Here, we characterized the biological function of AGO8b, a tassel-enriched AGO. The abundance of AGO8b transcripts gradually increased during tassel development from inception to gametogenesis and were enriched in the inflorescence meristem and axillary meristems of the tassel. Repressing AGO8b expression resulted in more spikelets, which contributed to a longer central spike of the tassel. Additionally, the transcripts of several HD-ZIP Ⅲ TFs that were canonical targets of micro RNA66(miR66) accumulated in the AGO8b repressed lines. We propose that AGO8b is a negative regulator of the determinacy of inflorescence and axillary meristems, and that it acts by interacting with the miR66-HD-ZIP Ⅲ TF regulatory pathway.
文摘Despite the presence of about 21%O2 in the atmosphere,organs of plants and mammals are inevitably subject to lower O2 tensions(pO2)due to high O2 demand in metabolic active cells and limited O2 transport efficiency.In humans,for example,the p O2 decreases from the ambient 21%(160 mm Hg)of the inhaled air to 2%-9%in the internal organs(Brahimi-Horn and Pouyssegur,2007).To cope with this limited oxygen supply,aerobic organisms have developed a variety of adaptive responses at cellular,tissue,and organismal levels(Bailey-Serres et al.,2012).Although low O2 tensions are the normal conditions for organs,the ambient 21%O2 is usually referred to as normoxia and the lower internal concentrations as hypoxia(van Dongen and Licausi,2015).
基金supported in part by funds from the Ministry of Science and Technology of China(Nos.2006CB910600 and 2007CB948200).
文摘Stem cells in plants,established during embry-ogenesis,are located in the centers of the shoot apical meristem(SAM)and the root apical meristem(RAM).Stem cells in SAM have a capacity to renew themselves and to produce new organs and tissues indefinitely.Although fully differentiated organs such as leaves do not contain stem cells,cells in such organs do have the capacity to re-establish new stem cells,especially under the induction of phytohormones in vitro.Cytokinin and auxin are critical in creating position signals in the SAM to maintain the stem cell organizing center and to position the new organ primordia,respectively.This review addresses the distinct features of plant stem cells and focuses on how stem cell renewal and differentiation are regulated in SAMs.
基金Acknowledgments The authors thank Dr Liying Du （Peking University, China） for technical help on the flow cytometric analysis. The authors also thank Dr Zhongchi Liu （University of Maryland, USA）, Dr Chun-Ming Liu （Institute of Botany CAS, China）, Dr Terry Matthew （University of Southampton, UK）, Professor Daochun Kong （Peking University, China） and Dr Naomi Nakayama （Yale University, USA） for critical comments and valuable discussion. This work was supported by the National Natural Science Foundation of China （GN 30625002 to L-J Qu）.
文摘As a cell cycle regulator, the Myb-related CDC5 protein was reported to be essential for the G2 phase of the cell cycle in yeast and animals, but little is known about its function in plants. Here we report the functional characterization of the CDC5 gene in Arabidopsis thaliana. Arabidopsis CDC5 （AtCDC5） is mainly expressed in tissues with high cell division activity, and is expressed throughout the entire process of embryo formation. The AtCDC5 loss-of-function mutant is embryonic lethal. In order to investigate the function of AtCDC5 in vivo, we generated AtCDC5-RNAi plants in which the expression of AtCDC5 was reduced by RNA interference. We found that the G2 to M （G2/M） phase transition was affected in the AtCDC5-RNAi plants, and that endoreduplication was increased. Additionally, the maintenance of shoot apical meristem （SAM） function was disturbed in the AtCDC5-RNAi plants, in which both the WUSCHEL （WUS）- CLAVATA （CLV） and the SHOOT MERISTEMLESS （STM） pathways were impaired. In situ hybridization analysis showed that the expression of STMwas greatly reduced in the shoot apical cells of the AtCDC5-RNAi plants. Moreover, cyclinB1 or Histone4 was found to be expressed in some of these cells when the transcript of STM was undetectable. These results suggest that AtCDC5 is essential for the G2/M phase transition and may regulate the function of SAM by controlling the expression ofSTMand WUS.
基金This work was supported by grants from the National Natural Science Foundation of China(31600990,31871217 and 32072037)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(20KJA210002)+2 种基金Project of Special Funding for Crop Science Discipline Development(yzuxk202006)the open funds of the State Key Laboratory of Crop Genetics and Germplasm Enhancement(ZW202010)the Key Research and Development Program of Jiangsu Province(BE2018357).
文摘In recent years,some super hybrid rice varieties were bred with strong culms and large panicles,which are mainly contributed by the ipa1-2D locus.A gain-of-function allele of OsSPL14 is the ipa1-2D and it can greatly increase the panicle primary branch number.However,the key downstream genes mediating this trait variation are not fully explored.In this study,we developed high-quality near-isogenic lines(NILs)with a difference of only 30 kb chromosomal segment covering the ipa1-2D locus.Using the NILs,we explored the impact of ipa1-2D on five sequential stages of early inflorescence development,and found that the locus can greatly enhance the initiation of primary branch meristems.A transcriptomic analysis was performed to unveil the downstream molecular network of ipa1-2D,and 87 genes were found differentially expressed,many of which are involved in metabolism and catalysis processes.In addition,transgenic lines of overexpression and RNA interference were generated to shape different levels of OsSPL14.They were also used to validate the expression variation explored by transcriptome.Based on the gene annotation,twelve potential downstream targets of ipa1-2D were selected,and their expression variation was confirmed by qRT-PCR analysis both in NILs and transgenic lines.This research expands the molecular network underlying ipa1-2D and provides novel gene information which might be involved in the control of panicle branching.We discussed the potential function of identified genes and highlighted their values for future function exploration and breeding application.
文摘In wheat plants at the vegetative growth stage, the shoot apical meristem (SAM) produces leaf primordia. When reproductive growth is initiated, the SAM forms an inflorescence meristem (IM) that differentiates a series of spikelet meristem (SM) as the branch. The SM then produces a series of floret meristem (FM) as the branch. To identify the mechanisms that regulate formation of the reproductive meristems in wheat, we have investigated a leaf initiation mutant, fushi-darake (fdk) which was developed by ion beam mutagenesis. The morphological traits were compared in wild type (WT) and fdk mutant plants grown in the experimental field. WT plants initiated leaves from SAM at regular intervals in spiral phyllotaxy, while fdk plants had 1/2 alternate phyllotaxy with rapid leaf emergence. The fdk plants have increased numbers of nodes and leaves compared with WT plants. The time interval between successive leaf initiation events (plastochron) was measured in plants grown in a growth chamber. The fdk plants clearly show the rapid leaf emergence, indicating a shortened plastochron. Each tiller in fdk plants branches at the upper part of the culm. The fine structure of organ formation in meristems of fdk plants was examined by scanning electron microscopy (SEM). The SEM analysis indicated that fdk plants show transformation of spikelet meristems into vegetative shoot meristems. In conclusion, the fdk mutant has a heterochronic nature, i.e., both reproductive and vegetative programs were simultaneously in operation during the reproductive phase, resulting in a shortened plastochron and transformation of reproductive spikelets into vegetative shoots.
文摘In the present research, we have investigated morphologicaltraits of different organs of Arabidopsis species in Iran. Trichomes on the aerial parts of three species were studied under anatomical microscopy. The species exist in Iran include: Arabidopsis thaliana (Heynh), Arabidopsis pumila (steph) and Arabidopsis wallichii (Hook & thomas). The form of trichomes, basal and stemleaves, fruit length, the attitude of fruit, the existence of trichomes on the fruit, and the color ofpetal are morphological traits which separate the species. Anatomical traits of the leaf and stem of studied species were analyzed using an optical microscope. In the stem, some traits such as the shape of stem in transverse incision, the thickness of skin, the existence of supporting tissue around phloem, the number of xylem and phloem and the wavy form of stele were distinct in the three species. In the leaf, some traits such as the shape of leaf, the number of palisade parenchyma layers, the uniformity of mesophyll tissue, and the density of trichomes were different in the three species. No significant difference has been observed in the study of reproductive meristem, except in A. wallichii. The only difference was related to the size of reproductive meristem of two species and the number of flowers produced from the meristems.
基金We gratefully acknowledge B Han from National Center for Gene Research, Chinese Academy of Sciences (CAS) and Rice Genome Resource Center (RGRC) for providing BAC clone, cDNA clone and Tosl7 insertion line. We thank Z-J Luo and M-J Chen from Shanghai Jiao Tong University for mutant screening and generation of F2 populations, X-Y Gao from Institute of Plant Physiology and Ecology, SIBS, CAS, for SEM, H Yu from Nation- al University Of Singapore for critical reading of this manuscript and H Ma from Fudan University for helpful discussion. This work was supported by funds from the National Basic Research Program of China (2009CB941500, 2006CB 101700), the National Natural Science Foundation of China (30725022, 30830014 and 90717109) and the Shanghai Leading Academic Discipline Project (B205).
文摘Although AGAMOUS-LIKE6 (AGL6) MADS-box genes are ancient with wide distributions in gymnosperms and angiosperms, their functions remain poorly understood. Here, we show the biological role of the AGL6-1ike gene, OsMADS6, in specifying floral organ and meristem identities in rice (Oryza sativa L.). OsMADS6 was strongly ex- pressed in the floral meristem at early stages. Subsequently, OsMADS6 transcripts were mainly detectable in paleas, lodicules, carpels and the integument of ovule, as well as in the receptacle. Compared to wild type plants, osmads6 mutants displayed altered palea identity, extra glume-like or mosaic organs, abnormal carpel development and loss of floral meristem determinacy. Strikingly, mutation of a SEPALLATA (SEP)-like gene, OsMADS1 (LHS1), enhanced the defect of osmads6 flowers, and no inner floral organs or glume-like structures were observed in whorls 2 and 3 of osmadsl-z osmads6-1 flowers. Furthermore, the osmadsl-z osmads6-1 double mutants developed severely indetermi- nate floral meristems. Our finding, therefore, suggests that the ancient OsMADS6 gene is able to specify "floral state" by determining floral organ and meristem identities in monocot crop rice together with OsMADS1.
基金supported by the National Natural Science Foundation of China(30670188)the National Key Project for Researches on Transgenic Plant of China(2009ZX08002-011B)the Education Department Project Of Henan Province,China(2010B210015)
文摘The homeobox transcription factor WUSCHEL(WUS)plays a critical role in keeping the balance between the maintenance and differentiation of stem cell population in shoot and floral meristems of Arabidopsis thaliana.The corresponding gene SlWUS is yet to be characterized in tomato.In order to characterize SlWUS gene and its biological function,we cloned it from tomato and analyzed its structure.Tissue expression showed that the SlWUS highly expressed in tomato flower abscission zone.The overexpression of SlWUS in Arabidopsis could trigger undifferentiation of plant flower organ and indeterminacy of flower identity,suggesting that SlWUS maybe involved in flower structure development as well as flower organ identity.Taken together,our results indicated that the SlWUS plays an important role in flower abscission zone and plant organ shedding.
文摘The homologous genes FLORICAULA (FLO) in Antirrhinum and LEAFY (LFY) in Arabidopsis are known to regu- late the initiation of flowering in these two distantly related plant species. These genes are necessary also for the expression of downstream genes that control floral organ identity. We used Arabidopsis LFY cDNA as a probe to clone and sequence a papaya ortholog of LFY, PFL. It encodes a protein that shares 61% identity with the Arabidopsis LFY gene and 71% identity with the LFY homologs of the two woody tree species: California sycamore (Platanus racemosa) and black cottonwood (Populus trichocarpa). Despite the high sequence similarity within two conserved regions, the N-terminal proline-rich motif in papaya PFL differs from other members in the family. This difference may not affect the gene function of papaya PFL, since an equally divergent but a functional LFY ortholog NEEDLY of Pinus radiata has been reported. Genomic and BAC Southern analyses indicated that there is only one copy of PFL in the papaya genome. In situ hybridization experiments demonstrated that PFL is expressed at a relatively low level in leaf primordia, but it is expressed at a high level in the floral meristem. Quantitative PCR analyses revealed that PFL was expressed in flower buds of all three sex types - male, female, and hermaphrodite with marginal difference between hermaphrodite and unisexual flowers. These data suggest that PFL may play a similar role as LFY in flower development and has limited effect on sex differentiation in papaya.
基金supported by the National Natural Science Foundation of China(Grant Nos.31971919,31730063)the Natural Science Foundation Project of Chongqing Science and Technology Commission,China(Grant No.cstc2020jcyj-jqX0020)+1 种基金National Key Program for Research and Development of China(Grant No.2017YFD0100202)Chongqing Graduate Research and Innovation Project Funding,China(Grant No.CYS20123).
文摘In rice,the spikelet is the basic unit of inflorescence,and its development is important for determining the grain yield and quality.We reported a rice spikelet mutant multi-floret spikelet 4(mfs4)which resulted in the production of extra floral organs or a whole extra floret,and elongated sterile lemmas.The results suggested that the mutation of the MFS4 gene interfered with spikelet meristem determinacy and floral organ identity.In addition,the plant height and the grain length and width in the mfs4 mutant were all less than those in the wild type.Using the bulked segregant analysis method,the MFS4 gene was localized in a 557-kb region on the long arm of chromosome 1.Sequence analysis showed that there was a C-base deletion at the open reading frame of LOC_Os01g67430.Further tests indicated that a wild type copy of LOC_Os01g67430 was able to reverse the mfs4 defects,which indicated that LOC_Os01g67430 was the MFS4 gene.The MFS4 gene encodes a lipase located in the mitochondria and is expressed strongly in the young inflorescence.qRT-PCR results showed that the expression of some genes that were known to regulate spikelet meristem determinacy and grain size were decreased in the mfs4 mutant,which indicated that the MFS4 gene regulates spikelet meristem determinacy and grain size by modulating the expression of these genes.
文摘It is vital to determine the effective photoperiods of maize for making full use of tropical germplasm, which is the foundation for determining the effect of latitude and planting date on the development of photoperiod-sensitive maize cultivars. The objective of this study is to determine the photoperiod-sensitive inductive phase using reciprocal transfer between long- day （LD） （15 h d^-1） and short-day conditions （SD） （9 h d^-1）. For Huangzao 4 and CML288, days to tassel and pollen shedding were recorded, and stem apical meristems （SAM） were observed by a laser scanning confocal microscope. The results show that the seedlings are insensitive to photoperiod when they are very young （juvenile）. However, after this period, LD delays flowering and increases the leaf numbers below the inflorescence, and the length of the interval of the photoperiod-sensitive inductive phase is longer under LD conditions than under SD conditions. Transferred from SD to LD, plants show a sudden decrease in leaf numbers once sufficient SD has been received for flower commitment. While transferred from LD to SD, plants have a continuous increase in leaf numbers during the photoperiod sensitive inductive phase under LD conditions. At the same time, when plants are competent to flowers, the obvious morphology is the elongation of maize SAM. There is an obvious variance of the photoperiod sensitive phase under LD and SD conditions in different maize.
基金supported by the National Natural Science Foundation of China (32071993, 32188102, 31971872, 31861143006,U2004204)Key Agricultural Technology Project(NK2022010302)。
文摘Increasing tiller number is a target of high-yield rice breeding. Identification of tiller-defect mutants and their corresponding genes is helpful for clarifying the molecular mechanism of rice tillering. Summarizing research progress on the two processes of rice tiller formation, namely the formation and growth of axillary meristem, this paper reviews the effects of genetic factors, endogenous hormones, and exogenous environment on rice tillering, finding that multiple molecular mechanisms and signal pathways regulating rice tillering cooperate rice tillering, and discusses future research objectives and application of its regulatory mechanism. Elucidation of theis mechanism will be helpful for breeding high-yielding rice cultivars with ideal plant type via molecular design breeding.
文摘Heat therapy followed by the isolation and in vitro culture of apical meristems is a suitable procedure for virus eradication. However, the period of heat treatment is usually long (28 - 50 days) and the yield of viable plants free of viruses after treatment is often low (<50%). Here, we describe an alternative method to obtain virus-free plants. We used traditional Galician cultivars, six apple trees and two pear trees, infected with Apple chlorotic leaf spot virus (ACLSV) and Apple mosaic virus (ApMV). We combined heat therapy of in vitro shoots using a temperature gradient from 25℃to 40℃increasing 1℃per day for a shorter period of time (18 days) with the posterior isolation and culture of apical meristems. All DNA samples analyzed, obtained from plants developed from meristems, were 100% free of ApMV and almost 90% free of ACLSV. With this in vitro procedure combined we obtained a good yield of tested plants free of viruses. Our method is fast and effective and it could be also useful to eradicate these and other viruses in other fruit trees.
基金Project supported by the National Key Basic Research Development Program of the Ministry of Science and Technology of China(Grant Nos.2001CB109002,2005CB120802)the National High-Techhology Research and Development Program of China(Grant No.2005AA2710330)+2 种基金the Science Foundation of Shanghai Municipal Commission of Science and Technology(Grant Nos.03JC14061,03DJ14016)the Program for New Century Excellent Talents in University(Grant No.NCET-040403)the Shuguang Plan of Shanghai Education Development Foundation(Grant No.04SG15)
文摘A rice mutant with Yaponica 9522 cultivar background Oryza sativa extraordinary glume 1 （Oseg 1） was identified from the M2 mutant pool mutagenized by ^60Co γ-ray. Compared with wild type plants, Oseg 1 developed longer empty glumes and rudimentary glumes. In some Oseg 1 mutants, the number of stamens of flowers was reduced and leaf-like lodicules occurred, and excessive lemma/palea-like organ could be observed in some mutant spikelets. This indicated that OsEG1 could regulate the development of rudimentary glumes, empty glumes, lemma/palea, lodicules, and stamens. Genetic analysis indicated that Oseg 1 came from a single recessive genetic locus. To clone OsEG1 gene, F2 population was constructed by a cross between Oseg 1 （Japonica） and Guangluai4 （Indica）. Using map-based cloning approach, OsEG1 was mapped on chromosome 4, between INDEL marker OS407 and WHM0466 with genetic distance of 2.0 cm and 1.0 cm, respectively. These results are useful for further cloning and functional analysis of the OsEG1 gene.
基金supported by Australian Research Council(DP170103352)an Australia-China Science and Research Fund Joint Research Centre grant ACSRF48187+2 种基金Start-up funding(Australia,13114779,62117250)for Dabing Zhang from the School of Agriculture,Food and Wine,The University of Adelaidethe Innovative Research Team,Ministry of Education of Chinathe 111 Project(B14016)
文摘The shape of an inflorescence varies among cereals,ranging from a highly branched panicle in rice to a much more compact spike in barley(Hordeum vulgare L.)and wheat(Triticum aestivum L.).However,little is known about the molecular basis of cereal inflorescence architecture.We profiled transcriptomes at three developmental stages of the barley main shoot apex—spikelet initiation,floral organ differentiation,and floral organ growth—and compared them with those from vegetative seedling tissue.Transcript analyses identified 3688 genes differentially transcribed between the three meristem stages,with a further 1394 genes preferentially expressed in reproductive compared with vegetative tissue.Coexpression assembly and Gene Ontology analysis classified these 4888 genes into 28 clusters,revealing distinct patterns for genes such as transcription factors,histone modification,and cell-cycle progression specific for each stage of inflorescence development.We also compared expression patterns of VRS(SIX-ROWED SPIKE)genes and auxin-,gibberellic acid-and cytokinin-associated genes between two-rowed and six-rowed barley to describe regulators of lateral spikelet fertility.Our findings reveal barley inflorescence phase-specific gene expression,identify new candidate genes that regulate barley meristem activities and flower development,and provide a new genetic resource for further dissection of the molecular mechanisms of spike development.
基金supported by The National Natural Science Foundation of China(31571588)。
文摘Background:Manual topping is a routine agronomic practice for balancing the vegetative and reproductive growth of cotton(Gossypium hirsutum)in China,but its cost-effectiveness has decreased over time.Therefore,there is an urgent need to replace manual topping with new approaches,such as biological topping.In this study,we examined the function of Gh REV transcription factors(a classⅢhomeodomain-leucine zipper family,HD-ZIPⅢ)in regulating the development of shoot apical meristem(SAM)in cotton with the purpose of providing candidate genes for biological topping of cotton in the future.Results:We cloned four orthologous genes of At REV in cotton,namely Gh REV1,Gh REV2,Gh REV3,and Gh REV4.All the Gh REVs expressed in roots,stem,leaves,and SAM.Compared with Gh REV1 and Gh REV3,the expression level of Gh REV2 and Gh REV4 was higher in the SAM.However,only Gh REV2 had transcriptional activity.Gh REV2 is localized in the nucleus;and silencing it via virus-induced gene silencing(VIGS)produced an abnormal SAM.Two key genes,Gh WUSA10 and Gh STM,which involved in regulating the development of plant SAM,showed about 50%reduction in their transcripts in VIGS-Gh REV2 plants.Conclusion:Gh REV2 positively regulates the development of cotton SAM by regulating Gh WUSA10 and Gh STM potentially.
