中国17个优良玉米自交系的分子标记杂合性及其与杂交种性状的关系研究

在玉米单交种育种中 ,鉴定高产杂交种和具有优良特性的自交系是一个重要的问题。研究以 1 7个优良玉米自交系为亲本 ,按照双列杂交配组合 ,利用 RAPD技术分析了 1 7个自交系的多态性以及 RAPD标记与 9个重要农艺性状 (包括产量 )的关系。基于 RAPD标记计算的相似系数聚类将 1 7个自交系分为 5个类群 ,经分析与系谱亲缘关系基本一致。杂交种性状及其特殊配合力与亲本间的遗传距离是高度相关的 ,与聚类前比较 ,聚类后平均遗传距离与平均产量、平均特殊配合力的相关系数显著提高 ,类间平均产量高于类内平均产量。RAPD技术可揭示优良玉米自交系的系谱亲缘关系 ,将自交系划分成不同的类群 ,从而为选择类间自交系杂交 ,进行亲本选配和分子标记辅助育种提供一种方法。     

8个合成群体改良玉米杂交种郑单958的育种潜力分析

玉米群体含有有利等位基因, 可作为改良杂交种的优异种质。针对持续改良我国主要玉米杂交种郑单958产量性状和商品品质的需求, 文章以8个合成群体为供体, 郑单958亲本自交系为受体, 组配16个测交组合。2009和2010年分别在北京顺义和河南新乡测量产量和籽粒容重。4个遗传参数评价显示, 合成群体可以作为新的有利等位基因供体改良杂交种性状, 其中WBMC-4和陕综3号两个群体具有同时改良杂交种产量和籽粒容重的潜力, 可分别用于改良亲本自交系郑58和昌7-2, 以及拓宽我国主要玉米类群PA和四平头的种质基础。     

中国17个优良玉米自交系的分子标记杂合性及其与杂交种性状的 …

在玉米单交种育种中,鉴定高产杂交种和具有优良特性的自交系是一个重要的问题。研究以１７个优良玉米自交系为亲本,按照双列杂交配组合,利用ＲＡＰＤ技术分析１７个自交系的多态性以及ＲＡＰＤ标记与９个重要农艺性状（包括产量）的关系。基于ＲＡＰＤ标记计算的相似系数聚类将１７个自交系分为５个类群,经分析与系谱关系基本一致。杂交种性状及其特殊配合力与亲本间的遗传距离是高度相关的,与聚类前比较,聚类后平均遗传距离与     

高粱穗部主要性状的配合力分析

以4个高粱不育系13163A、1358A、128A和407A,以及6个恢复系9.1R、213R、272R、381R、矮182R和早21R为试验材料,按照不完全双列杂交设计(NCII),对其F1的穗部主要性状进行配合力分析。结果表明:亲本穗部主要性状存在显著的遗传差异,主要表现为加性基因效应遗传的性状有:穗长、一级枝梗数、二级枝梗数、穗粒数;狭义遗传力大小顺序分别为:二级枝梗数一级枝梗数穗长穗粒数穗粒重千粒重。不同亲本的一般配合力(GCA)和特殊配合力(SCA)在不同穗部性状间存在较大差异。不育系407A和恢复系早21R、9.1R是综合性状较好的亲本材料,利用它们可组配出产量较高的杂交组合。恢复系272R组配的杂交种具有穗粒数较多、千粒重较小的特点,能满足市场上对小粒高粱的需求。深入分析高粱杂交亲本穗部主要性状表现,有利于对亲本材料的进一步了解和利用。     

玉米空间诱变后代SP4选系配合力效应分析

利用返回式卫星“实践八号”搭载3份玉米自交系08-641、RP125和18-599, 从SP4代中选出多个诱变系按不完全双列杂交设计配制杂交组合, 在四川和云南两个环境条件下进行种植鉴定。配合力分析结果表明, 3份玉米自交系经空间诱变后各性状的配合力发生不同程度的变化, 同组诱变系材料在四川和云南两种环境条件下的配合力表现存在较大差异, 且表现配合力差异的性状不同。诱变系C03的穗长、穗行数、行粒数和单株产量4个性状一般配合力(General combining ability, GCA)在该组试验中的正向效应值均表现为最大, 且显著高于基础材料08-641, 可能具有较大育种潜势; 诱变系C01和C04部分产量构成性状的GCA显著高于对照, 但单株产量GCA表现不明显, 需在育种中加以改良利用; 诱变系C06、R18和S22所配杂交组合在产量及产量构成性状上的特殊配合力(Specific combining ability, SCA)表现较优, 这些结果为玉米杂交种的选育提供了重要参考。     

玉米雌穗发育期基因差异表达与杂种优势的研究

杂种优势在提高粮食作物特别是玉米的产量方面具有重要的作用。然而,杂种优势的原理却仍然是一个世界性的难题。用12个玉米自交系及其按不完全双列杂交组配的33个杂交种为材料,分4个不同发育时期取杂交种及其亲本的雌穗组织,利用差异显示技术,分析杂种与亲本的基因差异表达类型及其与7个主要农艺性状的杂种表现和杂种优势的相关关系。发现1):在5种表达类型中单态表达(基因在杂交种和双亲中同时表达的类型)的数量最大,这说明杂种优势的形成不仅与基因的表达与否相关,还与大量基因的上调或下调表达相关;2):在玉米雌幼穗的发育初期杂交种与双亲的基因表达差异最大,这可能与雌穗发育初期器官的形成和发育相关,因此这一时期差异表达(在质的方面)的基因对产量性状和杂种优势的形成具有密切关系;3):综合各种基因表达类型与产量性状和杂种优势的关系,发现某些基因在杂种中的沉默表达可以促进籽粒的发育和抑制幼穗中小花的发育。     

甜椒隐性核基因雄性不育性的转育及利用

以甜椒核型雄性不育系AB91为不育源,以甜(辣)椒优良自交系为目标亲本,经过杂交、自交、姊妹交等转育手段,将AB91隐性核基因雄性不育性转育到优良甜(辣)椒自交系中,获得不育性稳定、恢复系广泛、配合力高、农艺性状优良的系列甜(辣)椒雄性不育两用系,为今后根据市场需求培育不同类型的杂交种奠定基础.目前,利用转育成的两用系已育成通过审定的甜椒品种冀研6号和两个正在参加区试的杂交种.     

基于玉米导入系群体的3个农艺性状QTL分析

通过回交育种程序结合SSR标记构建以玉米自交系农系531为受体亲本、10个具有不同农艺性状的自交系为供体的染色体片段导入系群体,在该群体BC3F3世代,利用GGT32图示基因型软件和Windows QTL IciMapping v1.0对导入片段进行检测、并结合田间调查对控制玉米穗位高、穗上叶夹角和株高的QTL进行分析.研究表明,导入系群体的创建在遗传结构上改良了农系531穗位偏高、穗上叶夹角偏大的不足,并得到基本符合育种目标的改良株系.通过QTL分析,在具有相同性状改良的单株上,分别检测到4个包含穗位高、4个包含穗上叶夹角和6个包含株高QTL的共同的导入染色体片段.     

密穗型水稻品种籽粒垩白性状改良研究

采用籽粒长宽比较大、穗部着粒密的散穗型材料(EG23)改良粳稻密穗型品种的籽粒垩白性状.结果表明,经改良后得到的密穗型品系EA6,与原亲本浙粳20比较,其穗部长度缩短,每穗总粒数增加,着粒密度增大,而籽粒垩白特性得到明显的改善,表明在穗部长度和着粒结构未得到改良的情况下,调节籽粒长宽比对改善密穗型品种籽粒垩白性状具有可能性.穗部不同粒位籽粒垩白性状改良的效果不同,穗顶部和穗中部的改良效果明显优于穗基部.设计的4个不同杂交配组方式中,以反回交配组方式(浙粳20/ EG23//浙粳20)选育效果最好.EA6具有较好的农艺性状,既可作为优异种质资源利用,也可直接应用于生产.这一结果从育种实践上较好地协调了密穗型品种高产与优质的矛盾,对于培育既有密穗型的高产株型又有优良籽粒外观品质的水稻品种具有重要意义.     

不同遗传背景下杂交籼稻功能叶与产量构成因素的相关

为明确水稻功能叶与产量构成因素间的相关性,以不同遗传背景下籼稻的10个不育系和16个恢复系为亲本,按照NCII设计配制两套双列杂交组合,对水稻12个功能叶性状与8个产量性状构成因素进行了相关分析,结果表明：3片功能叶叶长与叶面积、剑叶宽、倒2叶宽等性状之间均存在极显著正相关,功能叶夹角之间也存在极显著正相关,但不同遗传背景对夹角性状与9个形态性状之间的相关性则存在明显差异,在第一套组合中,其相关系数均为负值,且相关均不显著;而第二套组合则相反。8个产量构成因素中,单株穗数与平均穗长、着粒密度、穗实粒数以及穗着粒数之间存在极显著负相关,平均穗长与穗着粒数、结实率与单株产量呈显著或极显著正相关,遗传背景对产量组成上有较大影响,在第一套组合中单株产量主要由结实率、单株穗数以及穗实粒数等性状决定,而在第二套中则主要由穗实粒数和结实率等性状决定。在功能叶与产量构成因素的相关中,功能叶叶长、叶面积、剑叶宽、倒2叶宽与着粒密度、穗实粒数以及穗着粒数等3个性状之间存在显著或极显著正相关。12个水稻功能叶性状与8个产量构成因素之间的主成分分析表明,在不同的遗传背景下,产量构成因素均主要受叶面积和叶夹角影响,两种不同遗传背景中其累积贡献率分别为69.8%和84.0%。     

Performance prediction of F1 hybrids between recombinant inbred lines derived from two elite maize inbred lines

Selection of recombinant inbred lines (RILs) from elite hybrids is a key method in maize breeding especially in developing countries. The RILs are normally derived by repeated self-pollination and selection. In this study, we first investigated the accuracy of different models in predicting the performance of F₁ hybrids between RILs derived from two elite maize inbred lines Zong3 and 87-1, and then compared these models through simulation using a wider range of genetic models. Results indicated that appropriate prediction models depended on genetic architecture, e.g., combined model using breeding value and genome-wide prediction (BV+GWP) has the highest prediction accuracy for high V _D/V _A ratio (>0.5) traits. Theoretical studies demonstrated that different components of genetic variance were captured by different prediction models, which in turn explained the accuracy of these models in predicting the F₁ hybrid performance. Based on genome-wide prediction model (GWP), 114 untested F₁ hybrids possibly having higher grain yield than the original F₁ hybrid Yuyu22 (the single cross between Zong3 and 87-1) have been identified and recommended for further field test.     

Genetic structure and diversity among maize inbred lines as inferred from DNA microsatellites

Two hundred and sixty maize inbred lines, representative of the genetic diversity among essentially all public lines of importance to temperate breeding and many important tropical and subtropical lines, were assayed for polymorphism at 94 microsatellite loci. The 2039 alleles identified served as raw data for estimating genetic structure and diversity. A model-based clustering analysis placed the inbred lines in five clusters that correspond to major breeding groups plus a set of lines showing evidence of mixed origins. A "phylogenetic" tree was constructed to further assess the genetic structure of maize inbreds, showing good agreement with the pedigree information and the cluster analysis. Tropical and subtropical inbreds possess a greater number of alleles and greater gene diversity than their temperate counterparts. The temperate Stiff Stalk lines are on average the most divergent from all other inbred groups. Comparison of diversity in equivalent samples of inbreds and open-pollinated landraces revealed that maize inbreds capture <80% of the alleles in the landraces, suggesting that landraces can provide additional genetic diversity for maize breeding. The contributions of four different segments of the landrace gene pool to each inbred group's gene pool were estimated using a novel likelihood-based model. The estimates are largely consistent with known histories of the inbreds and indicate that tropical highland germplasm is poorly represented in maize inbreds. Core sets of inbreds that capture maximal allelic richness were defined. These or similar core sets can be used for a variety of genetic applications in maize.     

Relationships among maize inbred lines and populations from European and North-American origins as estimated using RFLP markers

RFLP markers have proven to be a reliable and highly informative tool for characterizing genetic diversity in maize. Joint analysis of inbred lines and populations should provide valuable information with respect to (1) a better understanding of the genetic basis of present elite germplasm and (2) the identification of populations that may prove to be useful sources of genetic diversity for breeding programs. Sixty-two inbred lines of known heterotic groups and ten maize populations, some of them significant contributors to the genetic basis of the heterotic groups, were assayed at 28 RFLP loci. Joint data analyses first underlined that the populations displayed a large number of alleles that were absent in the set of inbred lines. Associations among inbreds and populations further proved consistent with pedigree data of the inbreds and provided new information on the genetical basis of heterotic groups. In particular, European flint inbreds were revealed to be as close to the Northeastern U.S. flint population studied as to the typical European populations. These results advocate the analysis of larger sets of populations by means of molecular markers in order to (1) gain insight into the history of maize germplasm and (2) set up appropriate strategies for the use of genetic resources in breeding programs. Received: 23 February 1998 / Accepted: 5 February 1999     

Experimental evaluation of the potential of tropical germplasm for temperate maize improvement

 Commercial maize (Zea mays L.) in the USA has a restricted genetic base as newer hybrids are largely produced from crosses among elite inbred lines representing a small sample (predominantly about 6- to 8-base inbreds) of the Stiff stalk and Lancaster genetic backgrounds. Thus, expansion of genetic diversity in maize has been a continuous challenge to breeders. Tropical germplasm has been viewed as a useable source of diversity, although the integration of tropical germplasm into existing inbred line and hybrid development is laborious. The present study is an evaluation of the potential of tropical germplasm for temperate maize improvement. All possible single-, three-way-, and double-cross hybrids among three largely temperate and three temperate-adapted, all-tropical inbred lines were evaluated in yield-trial tests. Single-cross hybrids containing as much as 50–60% tropical germplasm produced 8.0 t ha^-1 of grain yield, equivalent to the mean yield of the commercial check hybrids. On the other hand, three-way and double-cross hybrids with the highest mean yield contained lower amounts of tropical germplasm, 10–19% and 34–44%, respectively. Overall, hybrids containing 10–60% tropical germplasm yielded within the range of the commercial hybrid checks. Hybrids with more than 60% tropical germplasm had significantly lower yields, and 100% tropical hybrids yielded the least among all hybrids evaluated. The results indicate that inbred lines containing tropical germplasm are not only a useful source to expand the genetic diversity of commercial maize hybrids, but they, also are competitive in crosses with temperate materials, producing high-yielding hybrids. These experimental hybrids exhibited good standability (comparable to the commercial check hybrids) but contained 1–2% higher grain moisture, leading to delayed maturity. Recurrent selection procedures are being conducted on derivatives of these materials to extract lines with superior yield, good standability, and reduced grain moisture which can be used for commercial exploitation. Received: 26 January 1998 / Accepted: 14 July 1998     

玉米重要自交系的肿囊腐霉茎腐病抗性鉴定与评价

由肿囊腐霉菌(Pythium inflatum Matthews)引起的玉米茎腐病是影响玉米产量的一种重要病害。为进一步拓展可利用的抗源,于2010-2011年在田间采用人工接种方法对287份重要的玉米自交系种质进行了玉米茎腐病的抗性鉴定评价。结果表明,287份鉴定材料中有171份自交系对茎腐病的抗性达到中抗以上水平,占鉴定材料的59.58%,其中高抗自交系共43份,占鉴定材料总数的14.98%;感病类型自交系共116份,占鉴定材料的40.42%,其中高感自交系共95份,占鉴定材料总数的33.10%。Lancaster、Reid及P群种质中具有丰富的茎腐病抗源,而塘四平头种质群中茎腐病抗源相对缺乏,多为感病类型。该研究结果可为今后我国玉米茎腐病抗性种质的引进和改良提供重要参考。     

Patterns of genomic variation in Chinese maize inbred lines and implications for genetic improvement

Key message

Genetic relationships among Chinese maize germplasms reveal historical trends in heterotic patterns from Chinese breeding programs and identify line Dan340 as a potential genome donor for elite inbred line Zheng58.

Abstract

The characterization of the genetic relationships, heterotic patterns and breeding history of lines in maize breeding programs allows breeders to efficiently use maize germplasm for line improvement over time. In this study, 269 temperate inbred lines, most of which have been widely used in Chinese maize breeding programs since the 1970s, were genotyped using the Illumina MaizeSNP50 BeadChip, which contains 56,110 single-nucleotide polymorphisms. The STRUCTURE analysis, cluster analysis and principal coordinate analysis results consistently revealed seven groups, of which five were consistent with known heterotic groups within the Chinese maize germplasm—Domestic Reid, Lancaster, Zi330, Tang SPT and Tem-tropic I (also known as “P”). These genetic relationships also allowed us to determine the historical trends in heterotic patterns during the three decades from 1970 to 2000, represented by Mo17 from Lancaster, HuangZaoSi (HZS) from Tang SPT, Ye478 from Domestic Reid and P178 from Tem-tropic I heterotic groups. Mo17-related commercial hybrids were widely used in the 1970s and 1980s, followed by the release of HZS- and Ye478-related commercial hybrids in the 1980s and 1990s, and the introduction of Tem-tropic I group in the 1990s and 2000s. Additionally, we identified inbred line Dan340 as a potential genome donor for Zheng58, which is the female parent of the most widely grown commercial hybrid ZhengDan958 in China. We also reconstructed the recombination events of elite line HZS and its 14 derived lines. These findings provide useful information to direct future maize breeding efforts.

     

Trends in genetic diversity among European maize cultivars and their parental components during the past 50 years

It has been claimed that the system that delivers the products of plant breeding reduces the diversity of cultivated varieties leading to an increased genetic vulnerability. The main goal of our study was to monitor the temporal trends in genetic diversity over the past five decades among maize cultivars with the largest acreage in Central Europe. Our objectives were to (1) investigate how much of the genetic diversity present in important adapted open-pollinated varieties (OPVs) has been captured in the elite flint germplasm pool, (2) examine changes in the genetic diversity among the most important commercial hybrids as well as in their dent and flint parents, (3) analyze temporal changes in allele frequencies between the dent and flint parental inbreds, and (4) investigate linkage disequilibrium (LD) trends between pairs of loci within the set of parental dent and flint lines. We examined 30 individuals of five prominent OPVs from Central Europe, 85 maize hybrids of economic importance, and their dent and flint parental components with 55 SSRs. LD was significant at probability level P=0.01 for 20.2% of the SSR marker pairs in the 82 dent lines and for 17.2% in the 66 flint lines. The dent and flint heterotic groups were clearly separated already at the beginning of hybrid breeding in Central Europe. Furthermore, the genetic variation within and among varieties decreased significantly during the five decades. The five OPVs contain numerous unique alleles that were absent in the elite flint pool. Consequently, OPVs could present useful sources for broadening the genetic base of elite maize breeding germplasm.     

Analysis of genetic diversity and relationships among waxy maize inbred lines in Korea using SSR markers

Information regarding the genetic diversity and genetic relationships among elite inbred lines is necessary to improve new cultivars in maize breeding programs. In this study, genetic diversity and genetic relationships were investigated among 84 waxy maize inbred lines using 50 SSR markers. A total of 269 alleles were identified at all the loci with an average of 5.38 and a range between 2 and 13 alleles per locus. The gene diversity values varied from 0.383 to 0.923 with an average of 0.641. The cluster tree generated using the described SSR markers recognized two major groups at 32% genetic similarity. Group I included 33 inbred lines while group II included 51 inbred lines. The clustering patterns of most of the waxy maize inbred lines did not clearly agree with their source, pedigree or geographic location. The average GS among all inbred lines was 35.7 ± 10.8. Analysis of waxy maize inbred lines collected from Korea and China at 50 SSR loci revealed higher values of average number of alleles (4.9) and gene diversity (0.638) in Korean inbred lines as compared to Chinese inbred lines (3.5 and 0.563, respectively). The information obtained from the present studies would be very useful for maize breeding programs in Korea.     

A new test for family-based association mapping with inbred lines from plant breeding programs

Association mapping holds great promise for the detection of quantitative trait loci (QTL) in plant breeding populations. The main objectives of this study were to (1) adapt the quantitative pedigree disequilibrium test to typical pedigrees of inbred lines produced in plant breeding programs, (2) compare the newly developed quantitative inbred pedigree disequilibrium test (QIPDT) with the commonly employed logistic regression ratio test (LRRT), with respect to the power and type I error rate of QTL detection, and (3) demonstrate the use of the QIPDT by applying it to flowering data of European elite maize inbreds. QIPDT and LRRT were compared based on computer simulations modeling 55 years of hybrid maize breeding in Central Europe. Furthermore, we applied QIPDT to a cross-section of 49 European elite maize inbred lines genotyped with 722 amplified fragment length polymorphism markers and phenotyped in four environments for days to anthesis. Compared to LRRT, the power to detect QTL was higher with QIPDT when using data collected routinely in plant breeding programs. Application of QIPDT to the 49 European maize inbreds resulted in a significant (P < 0.05) association located at a position for which a consensus QTL was detected in a previous study. The results of our study suggested that QIPDT is a promising QTL detection method for data collected routinely in plant breeding programs.