大豆巢式关联作图(NAM)群体构建及花色和种皮色遗传分析

巢式关联作图(Nested Association Mapping,NAM)群体在作物学遗传与育种研究中具有广泛的应用。本研究在前期大豆种质资源评价基础上,利用35份不同地区来源的代表性种质与中豆41(公共母本)杂交,构建了一套大豆NAM群体。PCA和聚类分析发现,不同亲本组合的RIL群体基本聚在一起,显示出清晰的遗传结构。利用该NAM群体亲本间花色和种皮色具有显著差异的RIL群体进行全基因组关联分析,定位到1个主要位点qFC13-1与花色显著关联,该位点与W1位点重合;定位到12个位点与种皮色显著相关,其中9个位点为3种以上方法共定位,3个位点为2种方法共定位,包括4个已知位点和8个新位点。研究结果表明,构建的NAM群体适于进行大豆相关性状遗传分析,为大豆复杂性状的遗传解析和育种实践提供了良好的基础材料。

大豆出苗期耐盐性鉴定方法建立及耐盐种质筛选

土壤盐渍化是影响农业生产的重要问题,筛选耐盐大豆资源对于大豆主产区盐渍化土壤的利用具有重要意义。以中黄35、中黄39、Williams82、铁丰8号、Peking和NY27-38为供试材料,以蛭石为培养基质,设0、100和150 mmol L?1 NaCl 3个处理,进行出苗期耐盐性鉴定,分析与生长相关的6个指标,旨在明确大豆出苗期耐盐性鉴定指标和评价方法。结果表明, 150 mmol L?1NaCl处理显著降低大豆的成苗率、株高、地上部鲜重、根鲜重、地上部干重和根干重,并且不同材料间差异显著。基于幼苗生长发育状况的耐盐指数方法与耐盐系数方法对6份种质耐盐性评价结果显著相关。耐盐指数法对植株无损坏、可省略种植对照,节约人力和物力,提高种质鉴定的效率。因此,以150 mmol L?1 NaCl作为出苗期耐盐鉴定浓度,以耐盐指数作为大豆出苗期耐盐鉴定评价指标,鉴定27份大豆资源,获得出苗期高度耐盐大豆(1级) 3份、耐盐大豆(2级) 7份,其中4份苗期也高度耐盐(1级),分别为运豆101、郑1311、皖宿1015和铁丰8号。本研究建立了一种以蛭石为基质,利用150 mmol L?1 NaCl处理,以耐盐指数作为评价指标的大豆出苗期耐盐性鉴定评价的简便方法,并筛选出4份出苗期和苗期均耐盐的大豆,对耐盐大豆种质资源的高效鉴定和耐盐大豆新品种培育具有重要意义。

A Dominant Locus, qBSC-1, Controls β Subunit Content of Seed Storage Protein in Soybean(Glycine max(L.) Merri.)

Soybean seed storage protein is one of the most important plant vegetable proteins, and β subunit is of great significance to enhance soybean protein quality and processing property. F2 segregated population and residual heterozygous lines(RHL) derived from the cross between Yangyandou(low level of β subunit) and Zhonghuang 13(normal level of β subunit) were used for mapping of β subunit content. Our results showed that β subunit content was controlled by a single dominant locus, qBSC-1(β subunit content), which was mapped to a region of 11.9 cM on chromosome 20 in F2 population of 85 individuals. This region was narrowed down to 2.5 cM between BARCSOYSSR_20_0997 and BARCSOYSSR_20_0910 in RHL with a larger population size of 246 individuals. There were 48 predicted genes within qBSC-1 region based on the reference genome(Glyma 1.0, Williams 82), including the two copies of β subunit coding gene CG4. An InDel marker developed from a thymine(TT) insertion in one copy of CG4 promoter region in Yangyandou cosegregrated with BARCSOYSSR_20_0975 within qBSC-1 region, suggesting that this InDel marker maybe useful for marker-assisted selection(MAS).

Development of Soybean EST-SSR Markers and Their Use to Assess Genetic Diversity in the Subgenus Soja

Developing expressed sequence tag-derived SSR(EST-SSR)markers is imperative in genetic research.In this paper,we reported 37 EST-SSR markers which were developed from 286 unigenes obtained from soybean cDNA library.Among the 286 markers designed for the 4 accessions of Glycine max and 6 of its wild progenitor(G.soja)within the subgenus Soja,209 markers amplified DNA fragments,taking 73.1% and 37 markers appeared to be polymorphic,which was 12.9% of the total.The 37 loci detected a total of 142 alleles,while the PIC values varied from 0.194 to 0.794.Both the number of alleles per locus and PIC value were significantly related to the SSR motif.Six EST-SSR loci may be fixed for different alleles between G.max and G.soja since they were particularly polymorphic among the 6 G.soja accessions.A neighbor-joining tree placed the G.max accessions together as a group within the G.soja,though the average genetic distance among G.soja accessions was much higher.These new EST-SSRs markers will be useful for genetic diversity analysis,genetic mapping construction and gene discovery in Soja subgenus.

Stability of growth periods traits for soybean cultivars across multiple locations

The growth periods(GPs, from planting/emergence to reproductive stage 8(R8) of soybean cultivars vary in different ecological regions, especially in China with a very complex soybean cropping system. In this study, a 3-yr experimental study was undertaken in three geographical locations of China from 2008 to 2010, including the Northeast(40.66–45.85°N), Huang-Huai(34.75–38.04°N) and southern(22.82–30.60°N) eco-regions with about 250 accessions in each region to clarify the classification of maturity group(MG) and identify the cultivars with stable GP to increase the knowledge about the GP distribution of soybean cultivars in China. GPs of soybean cultivars in different eco-regions were significant different with a gradual decrease from 115–125 d in the Northeast part to the 85–100 d in the southern part of China. The geographical location was the major factor for GP of cultivars from the Northeast, while the year of planting was the major factor affecting the stability of GPs in Huang-Huai summer and southern summer soybean. AMMI2(additive main effects and multiplicativeinteraction)-Biplot analysis showed that the GPs of soybean cultivars from the Northeast eco-region have a comparatively satisfactory environmental stability. Moreover, soybean cultivars with moderate GP/MG and stable environment adaptability in different eco-regions were identified based on the linear regression and AMMI analysis, which was important for the accurate classification of soybean MGs in future. Taken together, our results reflected the genetic diversity, geographical distribution and environmental stability of the Chinese soybean GP trait. Soybean cultivars with stable GP for various Chinese eco-regions would be beneficial for Chinese soybean genetic improvement, varietal introduction, exchange, and soybean breeding program for wide adaptability.

Genetic diversity center of cultivated soybean(Glycine max) in China——New insight and evidence for the diversity center of Chinese cultivated soybean

Information on the center of genetic diversity of soybean(Glycine max) will be helpful not only for designing efficient strategies for breeding programs, but also for understanding the domestication and origin of this species. Here, we describe an analysis of genetic diversity based on simple-sequence repeat(SSR) variations within a core collection of 2 111 accessions of Chinese soybean landraces. Prior to the diversity assessment, the geographic origin of each accession was mapped. The map was then divided into grids each 2.5° in latitude and 5° in longitude. We found two regions that had higher number of alleles(NA) and greater polymorphic information content(PIC) values than the others. These regions are adjacently located within grid position of 30°–35°N×105°–110°E, which includes the valley of the middle and lower reaches of the Wei River, and the valley of the upper reaches of the Hanjiang River. It was also observed that in many regions, genetic diversity decreased with the increase in distance from the center. Another region, in northern Hebei Province(115°–120°E×40°–42.5°N), was observed having higher diversity than any surrounding regions, indicating that this is a sub-center of soybean diversity. Based on the presented results, the domestication and origin of soybean are also discussed.

Analysis of SSRs Uncovers Hierarchical Structure and Genetic Diversity in Chinese Soybean Landraces

For clarifying the hierarchical patterns of population structure of soybean landraces in China, the seven clusters previously identified using Bayesian clustering of 1 504 soybean landraces based on SSR markers genotyping data were further analyzed. Using the largest value of ΔK, these landraces could be split into 20 sub-clusters, which was supported by highly significant pairwise Fst-values and generally in accordance with the geographic origin and sowing types. The autumn-sowing types ended up in one distinct sub-cluster from the otherwise summer-sowing type, where the autumn-sowing types are most likely derived from. The division into 20 sub-clusters explained 7.3% of the genetic variation, next to 9.7% present among the seven clusters, 81.1% residing among landraces within sub-clusters, and 1.9% within the landraces. The distribution pattern of genetic diversity among the sub-clusters of each cluster was uneven, with two HSuM sub-clusters (Central China) and some South China sub-clusters showing significantly higher level of genetic diversity.

The identification of presence/absence variants associated with the apparent differences of growth period structures between cultivated and wild soybeans

The cultivated soybean(Glycine max(L.) Merr.) was distinguished from its wild progenitor Glycine soja Sieb.& Zucc.in growth period structure,by a shorter vegetative phase(V),a prolonged reproductive phase(R) and hence a larger R/V ratio.However,the genetic basis of the domestication of soybean from wild materials is unclear.Here,a panel of 123 cultivated and 97 wild accessions were genotyped using a set of 24 presence/absence variants(PAVs) while at the same time the materials were phenotyped with respect to flowering and maturity times at two trial sites located at very different latitudes.The major result of this study showed that variation at PAVs is informative for assessing patterns of genetic diversity in Glycine spp.The genotyping was largely consistent with the taxonomic status,although a few accessions were intermediate between the two major clades identified.Allelic diversity was much higher in the wild germplasm than in the cultivated materials.A significant domestication signal was detected at 11 of the PAVs at 0.01 level.In particular,this study has provided information for revealing the genetic basis of photoperiodism which was a prominent feature for the domestication of soybean.A significant marker-trait association with R/V ratio was detected at 14 of the PAVs,but stripping out population structure reduced this to three.These results will provide markers information for further finding of R/V related genes that can help to understand the domestication process and introgress novel genes in wild soybean to broaden the genetic base of modern soybean cultivars.