[Objectives]This study was conducted to select superior maize combinations.[Methods]With the control maize variety Haihe 2 in the middle altitude area of Yunnan Province as the control,adopting a single-factor randomi...[Objectives]This study was conducted to select superior maize combinations.[Methods]With the control maize variety Haihe 2 in the middle altitude area of Yunnan Province as the control,adopting a single-factor randomized block three-replicate experiment design,a one-year field cultivation experiment was carried out in Luyin Village,Yongfeng Town,Zhaoyang District,Zhaotong City.[Results]A total of 11 new superior maize combinations including ZT-1 and ZT-2 were obtained.Through comprehensive comparison analysis with Haihe 2(CK),we selected six superior combinations of ZT-1,ZT-3,ZT-4,ZT-6,ZT-7 and ZT-9,which showed overall performance better than the control Haihe 2(CK)in terms of resistance,yield,and ear traits.[Conclusions]The selected 6 superior combinations have promotion value,and are recommended for higher-level trials and demonstrations.展开更多
Humankind has been through different periods of agricultural improvement aiming at enhancing our food supply and the performance of food crops. In recent years, whole genome sequencing and deep understanding of geneti...Humankind has been through different periods of agricultural improvement aiming at enhancing our food supply and the performance of food crops. In recent years, whole genome sequencing and deep understanding of genetic and epigenetic mechanisms have facilitated new plant breeding approaches to meet the challenge of growing population, dwindling resources, and changing climate. Here we proposed a simple and fast molecular breeding method, marker-assisted reverse breeding（MARB）, which will revert any maize hybrid into inbred lines with any level of required similarity to its original parent lines. Since all the pericarp DNA of a hybrid is from the maternal parent, whereas one half of the embryo DNA is from the maternal parent and the other half from the paternal parent, so we firstly extract DNA from seed embryo and pericarp of a selected elite hybrid separately and then we derived the genotypes of the two parents with high-density single nucleotide polymorphism（SNP） chips. The following marker-assisted selection was performed based on an Illumina low-density SNP chip designed with 192 SNPs polymorphic between the two parental genotypes, which were uniformly distributed on 10 maize chromosomes. This method has the advantages of fast speed, fixed heterotic mode, and quick recovery of beneficial parental genotypes compared to traditional pedigree breeding using elite hybrids. Meanwhile, MARB has the advantage of not requiring sophisticated transformation and double haploid（DH） technologies over RNA interference（RNAi）-mediated reverse breeding. In addition, MARB can also be used with feed corn harvested from big farms, which is often similar to F_2 populations, and the relevant transgenes in the population can be eliminated by marker-assisted selection. As a result, the whole global commercial maize hybrids can be utilized as germplasm for breeding with MARB technology. Starting with an F_2 population derived from an elite hybrid, our experiment indicates that with three cycles of marker-assisted selection, selected lines could recover over 80% of the parental genotypes and associated beneficial genes in a fixed heterotic mode. The success application of MARB in maize suggests that this technology is applicable to any hybrid crop to breed new inbreds with improved hybrid performance but the same heterotic mode. As chip technology becomes cheap, it would be expected that polymorphism screening and following marker-assisted selection could be done with one all-purpose high density chip. Several issues associated with MARB were discussed, including its rationale, efficiency and advantages, along with food/feed and environmental safety issues and applications of MARB in variety protection and marker-assisted plant breeding.展开更多
Haploid seedlings were inducted from different maize materials.At 2-3-leaf stage,maize haploids were treated with 0.06% colchicine and 2.0% dimethyl sulfoxide（DMSO） by dipping root,dripping heart leaf and acupunctur...Haploid seedlings were inducted from different maize materials.At 2-3-leaf stage,maize haploids were treated with 0.06% colchicine and 2.0% dimethyl sulfoxide（DMSO） by dipping root,dripping heart leaf and acupuncturing growing point,respectively.The doubling rate and mortality rate in different treatments were analyzed by variance analysis and multiple comparisons.The result showed that growing point acupuncturing method exhibited the highest doubling efficiency with an average doubling rate of 23%,seed-setting rate of 21.4%,and mortality rate of 16.3%.Composed with other two chemical doubling methods,growing point acupuncturing method significantly improved the doubling rate of maize haploids with a lower application dose of colchicine.This study laid the foundation for industrial application of haploid breeding techniques.展开更多
Six tropical maize inbred lines were crossed in a half diallel fashion and evaluated along with their F1 hybrids under low N (0 kg/ha) and high N(170 kg/ha), for grain yield, ear diameter, ear length, number of rows p...Six tropical maize inbred lines were crossed in a half diallel fashion and evaluated along with their F1 hybrids under low N (0 kg/ha) and high N(170 kg/ha), for grain yield, ear diameter, ear length, number of rows per ear, 100-kernel weight, ear leaf area, shoot dry weight, ear leaf chlorophyll content and plant height to determine their response to different level of N. Grain yield and ear leaf chlorophyll content measured by 48% lower under -N than under + N, and were most affected by -N. Ear length had the highest reduction under -N of 22%. Plant height and shoot dry weight were both reduced by 28%. Diallel analysis indicated significant additive as well as dominance variance for grain yield under -N. The same results were shown when one tolerant x nontolerant cross from the diallel hybrids was subjected to generation mean analysis which also indicated significant epistatic effects. These results suggest that S1 or S2 progeny selection may be an effective means of improving grain yield of tropical maize under low soil N.展开更多
Developing high-yield maize hybrids is critical for sustaining maize production,especially in the face of rapid climate changes and the growing global population.Exploring the genetic diversity and combining ability i...Developing high-yield maize hybrids is critical for sustaining maize production,especially in the face of rapid climate changes and the growing global population.Exploring the genetic diversity and combining ability in parental inbreds is needed for developing such high-yielding hybrids.Consequently,this study aimed at evaluating parental genetic diversity employing simple sequence repeats(SSR)markers,estimating effects of general(GCA)and specific(SCA)combining abilities for grain yield and yield contributing characters,identifying high yielding hybrids,and evaluating the association of SCA effects and performance of hybrids with genetic distance.Half-diallel mating scheme was utilized to develop 21 F_(1) hybrids from seven diverse maize inbred lines.The F_(1) hybrids along with check hybrid(SC-10),were investigated in a field trial over two growing seasons under arid conditions.The assessed F_(1) hybrids displayed significant genetic variations across all recorded traits.The inbreds P_(1) and P_(3) were detected as effective combiners to develop early maturing hybrids.Additionally,P_(3) and P_(4) were recognized as better combiners for improving grain yield and yield attributed characters.The hybrids P_(1)×P_(5) and P_(4)×P_(7) displayed significant SCA effects coupled with favorable agronomic performance.These hybrids are recommended for further evaluation and release as variety for arid environments to increase total maize production and contribute to food security.The alleles per locus differed between 2 and 5,with average of 3.5 alleles/locus.The polymorphic information content(PIC)altered between 0.21 to 0.74,with a mean of 0.56.Unweighted neighbor-joining tree grouped the inbred lines into three clusters,providing a valuable tool to decrease the crosses needed to be assessed in the trial field.Parental genetic distance varied from 0.63 to 0.90,averaging 0.79.The relationship between genetic diversity assessed through SSR markers and SCA effects was insignificant for all considered traits.Otherwise,SCA demonstrated a significant correlation with hybrid performance,suggesting that SCA serves as a reliable predictor for hybrid performance.The assessed maize inbred lines and developed hybrids revealed substantial genetic variability,offering valuable resources for enhancing maize productivity under arid conditions.The identified promising inbred lines(P_(1),P_(3),and P_(4))might be regarded as effective combiners for developing early-maturing genotypes and excellent combiners for enhancing yield attributes.Notably,the developed hybrids P_(1)×P_(5) and P_(4)×P_(7) possessed significant SCA alongside superior yield traits.SCA demonstrated a significant correlation with hybrid performance,suggesting its potential as a reliable predictor for the performance of developed hybrids.展开更多
Root growth has a fundamental role in nitrogen （N） use efficiency. Nevertheless, little is known about how modem breeding progress has affected root growth and its responses to N supply. The root and shoot growth of...Root growth has a fundamental role in nitrogen （N） use efficiency. Nevertheless, little is known about how modem breeding progress has affected root growth and its responses to N supply. The root and shoot growth of a core set of 11 representative Chinese maize （Zea mays L.） hybrids released between 1973 and 2009 were investigated under high N （4 mmol L^-1, HN） and low N （0.04 mmol L^-1, LN） levels in a solution culture system. Compared with LN, HN treatment decreased root dry weight （RDW）, the root： shoot ratio （R/S）, and the relative growth rate for root dry weight （RGRroot）, but increased the total root length （TRL） and the total lateral root length （LRL）. The total axial root length （ARL） per plant was reduced under HN, mostly in hybrids released before the 1990s. The number of seminal roots （SRN） was largely unaffected by different N levels. More recently released hybrids showed higher relative growth rates in the shoot under both HN and LN. However, the roots only showed increased RGR under HN treatment. Correspondingly, there was a positive linear relationship with the year of hybrid release for TRL, LRL and ARL under HN treatment. Together, these results suggest that while shoot growth of maize has improved, its root growth has only improved under high N conditions over the last 36 years of selective breeding in China. Improving root growth under LN conditions may be necessary to increase the N use efficiency of maize.展开更多
Numerous research publications over the past 20 years have made it quite clear that a better understanding of the molecular and genetic basis for variation in root system architecture（RSA）will greatly aid the develo...Numerous research publications over the past 20 years have made it quite clear that a better understanding of the molecular and genetic basis for variation in root system architecture（RSA）will greatly aid the development of crop varieties with improved and more ef ficient nutrient and water acquisition under limiting conditions.展开更多
文摘[Objectives]This study was conducted to select superior maize combinations.[Methods]With the control maize variety Haihe 2 in the middle altitude area of Yunnan Province as the control,adopting a single-factor randomized block three-replicate experiment design,a one-year field cultivation experiment was carried out in Luyin Village,Yongfeng Town,Zhaoyang District,Zhaotong City.[Results]A total of 11 new superior maize combinations including ZT-1 and ZT-2 were obtained.Through comprehensive comparison analysis with Haihe 2(CK),we selected six superior combinations of ZT-1,ZT-3,ZT-4,ZT-6,ZT-7 and ZT-9,which showed overall performance better than the control Haihe 2(CK)in terms of resistance,yield,and ear traits.[Conclusions]The selected 6 superior combinations have promotion value,and are recommended for higher-level trials and demonstrations.
基金supported by the Jilin Spring Corn and Rice High Yield Production System in Large Area,a project of Ministry of Science and Technology,China(2012BAD04B02)the Open Fund from Ministry of Agricultural Scientific Observing and Experimental Station of Maize in Plain Area of Southern Region,China(NT201405)+1 种基金the Agriculture Technological Innovation and Industrialization Project of Nantong City,China(HL2013026)Autonomous Innovation Project of Jiangsu Agricultural Science&Technology,China(CX(15)1005)
文摘Humankind has been through different periods of agricultural improvement aiming at enhancing our food supply and the performance of food crops. In recent years, whole genome sequencing and deep understanding of genetic and epigenetic mechanisms have facilitated new plant breeding approaches to meet the challenge of growing population, dwindling resources, and changing climate. Here we proposed a simple and fast molecular breeding method, marker-assisted reverse breeding（MARB）, which will revert any maize hybrid into inbred lines with any level of required similarity to its original parent lines. Since all the pericarp DNA of a hybrid is from the maternal parent, whereas one half of the embryo DNA is from the maternal parent and the other half from the paternal parent, so we firstly extract DNA from seed embryo and pericarp of a selected elite hybrid separately and then we derived the genotypes of the two parents with high-density single nucleotide polymorphism（SNP） chips. The following marker-assisted selection was performed based on an Illumina low-density SNP chip designed with 192 SNPs polymorphic between the two parental genotypes, which were uniformly distributed on 10 maize chromosomes. This method has the advantages of fast speed, fixed heterotic mode, and quick recovery of beneficial parental genotypes compared to traditional pedigree breeding using elite hybrids. Meanwhile, MARB has the advantage of not requiring sophisticated transformation and double haploid（DH） technologies over RNA interference（RNAi）-mediated reverse breeding. In addition, MARB can also be used with feed corn harvested from big farms, which is often similar to F_2 populations, and the relevant transgenes in the population can be eliminated by marker-assisted selection. As a result, the whole global commercial maize hybrids can be utilized as germplasm for breeding with MARB technology. Starting with an F_2 population derived from an elite hybrid, our experiment indicates that with three cycles of marker-assisted selection, selected lines could recover over 80% of the parental genotypes and associated beneficial genes in a fixed heterotic mode. The success application of MARB in maize suggests that this technology is applicable to any hybrid crop to breed new inbreds with improved hybrid performance but the same heterotic mode. As chip technology becomes cheap, it would be expected that polymorphism screening and following marker-assisted selection could be done with one all-purpose high density chip. Several issues associated with MARB were discussed, including its rationale, efficiency and advantages, along with food/feed and environmental safety issues and applications of MARB in variety protection and marker-assisted plant breeding.
文摘Haploid seedlings were inducted from different maize materials.At 2-3-leaf stage,maize haploids were treated with 0.06% colchicine and 2.0% dimethyl sulfoxide（DMSO） by dipping root,dripping heart leaf and acupuncturing growing point,respectively.The doubling rate and mortality rate in different treatments were analyzed by variance analysis and multiple comparisons.The result showed that growing point acupuncturing method exhibited the highest doubling efficiency with an average doubling rate of 23%,seed-setting rate of 21.4%,and mortality rate of 16.3%.Composed with other two chemical doubling methods,growing point acupuncturing method significantly improved the doubling rate of maize haploids with a lower application dose of colchicine.This study laid the foundation for industrial application of haploid breeding techniques.
文摘Six tropical maize inbred lines were crossed in a half diallel fashion and evaluated along with their F1 hybrids under low N (0 kg/ha) and high N(170 kg/ha), for grain yield, ear diameter, ear length, number of rows per ear, 100-kernel weight, ear leaf area, shoot dry weight, ear leaf chlorophyll content and plant height to determine their response to different level of N. Grain yield and ear leaf chlorophyll content measured by 48% lower under -N than under + N, and were most affected by -N. Ear length had the highest reduction under -N of 22%. Plant height and shoot dry weight were both reduced by 28%. Diallel analysis indicated significant additive as well as dominance variance for grain yield under -N. The same results were shown when one tolerant x nontolerant cross from the diallel hybrids was subjected to generation mean analysis which also indicated significant epistatic effects. These results suggest that S1 or S2 progeny selection may be an effective means of improving grain yield of tropical maize under low soil N.
基金supported by Princess Nourah bint Abdulrahman University Researchers Supporting Project number(PNURSP2024R318)Princess Nourah bint Abdulrahman University,Riyadh,Saudi Arabia.The authors extend their appreciation to the Deanship of Research and Graduate Studies at King Khalid University for funding this work through Large Research Project under grant number RGP2/342/45supported by the Deanship of Scientific Research,Vice Presidency for Graduate Studies and Scientific Research,King Faisal University,Saudi Arabia(KFU241870).
文摘Developing high-yield maize hybrids is critical for sustaining maize production,especially in the face of rapid climate changes and the growing global population.Exploring the genetic diversity and combining ability in parental inbreds is needed for developing such high-yielding hybrids.Consequently,this study aimed at evaluating parental genetic diversity employing simple sequence repeats(SSR)markers,estimating effects of general(GCA)and specific(SCA)combining abilities for grain yield and yield contributing characters,identifying high yielding hybrids,and evaluating the association of SCA effects and performance of hybrids with genetic distance.Half-diallel mating scheme was utilized to develop 21 F_(1) hybrids from seven diverse maize inbred lines.The F_(1) hybrids along with check hybrid(SC-10),were investigated in a field trial over two growing seasons under arid conditions.The assessed F_(1) hybrids displayed significant genetic variations across all recorded traits.The inbreds P_(1) and P_(3) were detected as effective combiners to develop early maturing hybrids.Additionally,P_(3) and P_(4) were recognized as better combiners for improving grain yield and yield attributed characters.The hybrids P_(1)×P_(5) and P_(4)×P_(7) displayed significant SCA effects coupled with favorable agronomic performance.These hybrids are recommended for further evaluation and release as variety for arid environments to increase total maize production and contribute to food security.The alleles per locus differed between 2 and 5,with average of 3.5 alleles/locus.The polymorphic information content(PIC)altered between 0.21 to 0.74,with a mean of 0.56.Unweighted neighbor-joining tree grouped the inbred lines into three clusters,providing a valuable tool to decrease the crosses needed to be assessed in the trial field.Parental genetic distance varied from 0.63 to 0.90,averaging 0.79.The relationship between genetic diversity assessed through SSR markers and SCA effects was insignificant for all considered traits.Otherwise,SCA demonstrated a significant correlation with hybrid performance,suggesting that SCA serves as a reliable predictor for hybrid performance.The assessed maize inbred lines and developed hybrids revealed substantial genetic variability,offering valuable resources for enhancing maize productivity under arid conditions.The identified promising inbred lines(P_(1),P_(3),and P_(4))might be regarded as effective combiners for developing early-maturing genotypes and excellent combiners for enhancing yield attributes.Notably,the developed hybrids P_(1)×P_(5) and P_(4)×P_(7) possessed significant SCA alongside superior yield traits.SCA demonstrated a significant correlation with hybrid performance,suggesting its potential as a reliable predictor for the performance of developed hybrids.
基金supported by the National Basic Research Program of China (Grant No. 2009CB11860)the National Natural Science Foundation of China (Grant Nos. 31071852 and 30821003)the Special Fund for Agriculture Profession (Grant No. 201103003)
文摘Root growth has a fundamental role in nitrogen （N） use efficiency. Nevertheless, little is known about how modem breeding progress has affected root growth and its responses to N supply. The root and shoot growth of a core set of 11 representative Chinese maize （Zea mays L.） hybrids released between 1973 and 2009 were investigated under high N （4 mmol L^-1, HN） and low N （0.04 mmol L^-1, LN） levels in a solution culture system. Compared with LN, HN treatment decreased root dry weight （RDW）, the root： shoot ratio （R/S）, and the relative growth rate for root dry weight （RGRroot）, but increased the total root length （TRL） and the total lateral root length （LRL）. The total axial root length （ARL） per plant was reduced under HN, mostly in hybrids released before the 1990s. The number of seminal roots （SRN） was largely unaffected by different N levels. More recently released hybrids showed higher relative growth rates in the shoot under both HN and LN. However, the roots only showed increased RGR under HN treatment. Correspondingly, there was a positive linear relationship with the year of hybrid release for TRL, LRL and ARL under HN treatment. Together, these results suggest that while shoot growth of maize has improved, its root growth has only improved under high N conditions over the last 36 years of selective breeding in China. Improving root growth under LN conditions may be necessary to increase the N use efficiency of maize.
文摘Numerous research publications over the past 20 years have made it quite clear that a better understanding of the molecular and genetic basis for variation in root system architecture（RSA）will greatly aid the development of crop varieties with improved and more ef ficient nutrient and water acquisition under limiting conditions.
