利用大豆分子连锁图定位大豆孢囊线虫4号生理小种抗性QTL

QTL Mapping Genes Conferring Resistance to Race 4 of Soybean Cyst Nematode in Soybean ZDD2315 (Glycine max (L) Merr.) Based on Public Molecular Genetic Linkage Map

大豆孢囊线虫 (SCN ,HeteroderaglycinesIchinohe)是一种土传的定居性内寄生线虫 ,是引起大豆黄萎病的病原 ,是大豆生产上危害最大的病害之一。SCN的生理小种多达十几种 ,在我国大豆孢囊线虫病原主要为 4号生理小种 ,它是现有生理小种中致病力最强的小种。经典遗传学研究已经确定大豆孢囊线虫抗性基因由 1- 4对核基因控制 ,估计有 10个以上的抗性座位。近年来分子标记技术及QTL定位方法的发展为深入研究该病害的抗性遗传规律提供了有效的手段 ,这对加速我国抗大豆抗孢囊线虫新品种培育具有重要意义。本研究以晋豆 2 3×ZDD2 315组合F2 群体 (2 5 3个单株 )为试验材料 ,其中灰布支黑豆 (ZDD2 315 )是我国山西省农家品种 ,对大豆孢囊线虫 4号生理小种表现为高抗。利用塑料钵柱法进行SCN抗性鉴定 ,构建大豆孢囊线虫抗性主座位所在区域的分子图谱 ,并进行SCN的QTL定位及遗传效应分析。根据已发表的大豆A和G连锁群的分子遗传图谱 ,应用BSA法 ,获得了 8个与SCN4号生理小种抗性基因相关的SSR标记 ,它们是Satt0 38(176bp/ 182bp) ,Satt30 9(130bp/ 135bp) ,Satt6 10 (2 4 0bp/ 2 2 2bp) ,Sat_14 1(189bp/ 184bp) ,Satt187(30 0bp/ 2 5 0bp) ,Satt315 (2 5 3bp/ 2 4 8bp) ,Satt6 32 (2 86bp/ 2 90bp)和Sat_16

Soybean Cyst Nematode (SCN, Heterodera glycine Ichinohe ), a kind of soilborn sedentary endoparasite and the pathogen of soybean chlorsis, is one of the most economically destructive disease of soybean. There are more than ten physiological races, SCN race 4 is the predominant race and the most damaging soybean pathogen in China. Classical genetic studies demonstrated that the resistance to SCN is controlled by 1 to 4 loci, recent studies suggested that there should be more than ten resistant loci in soybean. The advent of molecular markers and quantitative trait locus (QTL) mapping approachs in the last decade gives an efficient alternative to study the mechanism of resistant to SCN, it will be considerable significance to accelerate the research of SCN resistance breeding.A population of 253 F 2:3 families which was generated from a cross between ZDD2315 and Jinbean23 were used for molecular marker identification. ZDD2315, a local germplasm of Shanxi province, is high resistant to SCN race 4. Jinbean 23 is a releasing cultivar and is susceptible to SCN race 4. We evaluate the resistance of soybean by counting the numbers of SCN cyst in soybean seedling root planting in plastic vessels. In this research we constructed molecular map in the regions of main resistance locus. QTLs conferring resistance to SCN were detected and the genetic effects of each QTL were also evaluated. According to the linkage group A and G of published soybean molecular linkage map, total twenty SSRs were adopted in this research. Eight SSRs were identified in the F 2:3 population,they are Satt038 (176bp,182bp), Satt309 (130bp,135bp), Satt610 (240bp,222bp), Satt187 (300bp,250bp), Sat141 (189bp,184bp), Satt315 (253bp,248bp), Satt632 (286bp,290bp), Sat162 (200bp,286bp) Those SSRs are co dominant, single locus, good reproducible and stable. A hundred of ISSR markers were used to screen resistance to SCN race 4 by means of bulked segregant analysis (BSA). One ISSR marker (UBC811) was identified to be related to SCN resistance. The ISSR marker is dominant, an amplified band of 340bp appeared in the susceptible parent and correspondent F 2 lines. One morphologic agronomic trait, black seed coat, was also investigated in F 2 population. The result showed that black seed coat (BSC) is separated by expected ratio of 3:1, and can be predicted as a recessive allele in controlling seed coat color. A molecular map was constructed using Mapmaker program with those markers and two linkage groups were obtained. Five markers, Sat141, Satt610, Satt038, Satt309 and UBC811, were mapped to linkage group G with a length of 50 5cM. Four markers including Satt315, Satt187, Satt632, Sat162 and one morphologic marker (BSC) were mapped to linkage group A with a length of 53 7cM. By means of complicated interval mapping, three QTLs had been mapped to soybean linkage A and G, respectively, conferring resistance to SCN race 4. There is one mapped QTL on linkage group G and is 2 0cM away from Satt610 marker,it is named rhg R4g1 and explains 15 87% of the phenotypic variation. There are of the two QTLs, which is 0 2cM away from Sat162 marker and 1 6cM from BSC marker on linkage group A, respectively. They are named rhg R4a1 and rhg R4a2 that explains 11 31% and 6 15% of the total phenotypic variation,respectively. Gene actions of rhg R4a1, rhg R4a2 and rhg R4g1, are partly dominant, dominant and overdominant, respectively. The sum of variation of 3 QTLs is 33 33%. In the case of the SSR markers Satt610,which is 2 0cM away from the QTL of rhg R4g1 on linkage group G, and Sat162, which is 0 2cM away from the QTL of rhg R4a2 on linkage group A, seven of forty one soybean varieties used in this study were identified to have the special resistant banding patterns. The result shows that Satt610 and Sat162 makers associated with loci conferring SCN race 4 resistance would be useful in breeding program using marker assisted selection to assistantly identificate resistance disease trait of SCN.