Identification of QTLs for yield and yield components of barley under different growth conditions

Waterlogging is a major abiotic stress limiting barley (Hordeum vulgare L.) yield and its stability in areas with excessive rainfall.Identification of genomic regions influencing the response of yield and its components to waterlogging stress will enhance our understanding of the genetics of waterlogging tolerance and the development of more tolerant barley cultivars.Quantitative trait loci (QTLs) for grain yield and its components were identified using 156 doubled haploid (DH) lines derived from a cross be...     

Quantitative trait loci analysis for rice seed vigor during the germination stage

Seed vigor is an important characteristic of seed quality, and rice cultivars with strong seed vigor are desirable in direct-sowing rice production for optimum stand establishment. In the present study, the quantitative trait loci (QTLs) of three traits for rice seed vigor during the germination stage, including germination rate, final germination percentage, and germination index, were investigated using one recombinant inbred line (RIL) population derived from a cross between japonica Daguandao and indica IR28, and using the multiple interval mapping (MIM) approach. The results show that indica rice presented stronger seed vigor during the germination stage than japonica rice. A total of ten QTLs, and at least five novel alleles, were detected to control rice seed vigor, and the amount of variation (R ²) explained by an individual QTL ranged from 7.5% to 68.5%, with three major QTLs with R ²>20%. Most of the QTLs detected here are likely to coincide with QTLs for seed weight, seed size, or seed dormancy, suggesting that the rice seed vigor might be correlated with seed weight, seed size, and seed dormancy. At least five QTLs are novel alleles with no previous reports of seed vigor genes in rice, and those major or minor QTLs could be used to significantly improve the seed vigor by marker-assisted selection (MAS) in rice.     

Mapping of quantitative trait loci using the skew-normal distribution

In standard interval mapping (IM) of quantitative trait loci (QTL), the QTL effect is described by a normal mixture model. When this assumption of normality is violated, the most commonly adopted strategy is to use the previous model after data transformation. However, an appropriate transformation may not exist or may be difficult to find. Also this approach can raise interpretation issues. An interesting alternative is to consider a skew-normal mixture model in standard IM, and the resulting method is here denoted as skew-normal IM. This flexible model that includes the usual symmetric normal distribution as a special case is important, allowing continuous variation from normality to non-normality. In this paper we briefly introduce the main peculiarities of the skew-normal distribution. The maximum likelihood estimates of parameters of the skew-normal distribution are obtained by the expectation-maximization (EM) algorithm. The proposed model is illustrated with real data from an intercross experiment that shows a significant departure from the normality assumption. The performance of the skew-normal IM is assessed via stochastic simulation. The results indicate that the skew-normal IM has higher power for QTL detection and better precision of QTL location as compared to standard IM and nonparametric IM.     

Comparative mapping of QTLs for Al tolerance in rice and identification of positional Al-induced genes

INTRODUCTION Aluminum (Al) toxicity is one of the mostimportant yield-limiting factors for crop grown onacid upland and lowland acid sulphate soils (IRRI,1978). Al toxicity results in a reduced and damagedroot system, which in turn causes the affectedplants to be susceptible to drought stress and min-eral nutrient deficiencies (Foy, 1988). The physio-logical and biochemical mechanisms of the toxiceffect of Al on root elongation had been extensivelyinvestigated (Matsumoto, 2000). T…     

Identification of candidate genes for drought stress tolerance in rice by the integration of a genetic （QTL） map with the rice genome physical map

INTRODUCTION Drought stress is a major constraint to rice(Oryza sativa) production and yield stability in rainedecosystems (Dey and Upadhyaya, 1996). Rice mustbe made more drought tolerant, but this is a somewhatcontradictory objective considering that rice is mostcommonly grown under flooded conditions. Achiev-ing drought tolerance in rice will require a deeperunderstanding of the possible physiological mecha-nisms available for water stress tolerance and theidentification of favo…     

复杂数量性状(QTLs)的遗传分析方法

近20年是统计遗传学应用于植物数量性状的研究发展最快的时期，随着计算技术的迅猛发展和分子标记的普遍应用，对数量性状的遗传剖析能力也在逐渐加强，认识也在逐步深入。本文综述了近20多年来关于植物数量性状的研究方法，特别介绍多维性状的遗传检测方法。     

QTL analysis of flag leaf in barley (Hordeum vulgare L.) for morphological traits and chlorophyll content

To understand genetic patterns of the morphological and physiological traits in flag leaf of barley, a double haploid (DH) population derived from the parents Yerong and Franklin was used to determine quantitative trait loci (QTL) controlling length, width, length/width, and chlorophyll content of flag leaves. A total of 9 QTLs showing significantly additive effect were detected in 8 intervals on 5 chromosomes. The variation of individual QTL ranged from 1.9% to 20.2%. For chlorophyll content expressed as SPAD value, 4 QTLs were identified on chromosomes 2H, 3H and 6H; fur leaf length and width, 2 QTLs located on chromosomes 5H and 7H, and 2 QTLs located on chromosome 5H were detected; and for length/width, 1 QTL was detected on chromosome 7H. The identification of these QTLs associated with the properties of flag leaf is useful for barley improvement in breeding programs.     

杂交稻中共显性RAPD标记及产量性状基因的检测

ＲＡＰＤ标记是利用含有１０（或９）个碱基的随机引物（单引物）,通过聚合酶链式反应（ＰＣＲ）对模板ＤＮＡ进行随机扩增,比较不同基因组ＤＮＡ的差异,ＲＡＰＤ标记具有样品用量少,灵敏度高,检测容易等优点,因而比ＲＦＬＰ更易于应用,但ＲＡＰＤ是显性标记,在分离群体中不能区别纯合显性和杂合显性个体。     

油菜开花性状的QTL作图分析

分别用单标记分析法、区间作图法、复合区间作图法和贝叶斯方法对油菜开花性状进行QTL作图,初步估计出QTL的位置,并分析比较各种作图方法．     

Analysis of digenic epistatic effects and<Emphasis Type="Italic">QE</Emphasis> interaction effects QTL controlling grain weight in rice

Immortalized F₂ population of rice (Oryza sativa L.) was developed by randomly mating F₁ among recombinant inbred (RI) lines derived from (Zhenshan 97B × Minghui 63), which allowed replications within and across environments. OTL (quantitative trait loci) mapping analysis on kilo-grain weight of immortalized F₂ population was performed by using newly developed software for QTL mapping, QTLMapper 2.0. Eleven distinctly digenic epistatic loci included a total of 15 QTL were located on eight chromosome. QTL main effects of additive, domainance, and additive × additive, additive × domainance, and dominance × dominance interactions were estimated. Interaction effects between QTL main effects and environments (QE) were predicted. Less than 40% of single effects, most of which were additive effects, for identified QTL were significant at 5% level. The directional difference for QTL main effects suggested that these QTL were distributed in parents in the repulsion phase. This should make it feasible to improve kilo-grain weight of both parents by selecting apprents in the repulsion phase. This should make it feasible to improve kilo-grain weight of both parents by selecting appropriate new recombinants. Only few of theQE interaction effects were significant. Application prospect for QTL mapping achievements in genetic breeding was discussed. Project (No. 39893354) supported by the National Natural Science Foundation of China