Genetic Diversity Of Soybean Germplasm Resistant To Phytophthora Root Rot Based On SSR Markers

Phytophthora root rot, caused by Phytophthora sojae, is one of the most importantdiseases of soybean (Glycine max (L.) Merr.) in major soybean producing countries of theworld. This disease is spreading fast in China. Using resistant cultivars is the mostefficient and economic method to control the disease. However, the P. sojae has a greatnumber of races and mutate rapidly, and the constitution of viranlence is very complex.With modern soybean production development, the genetic basis of cultivar soybean isbecoming more and more narrowly. So, for sustainable development of soybeanproduction, enlarging utilization of genetic resources and widening the genetic basementof cultivar soybean.is necessary. In this research we used SSR makers to evaluate geneticdiversity of soybean cultivar or lines resistance to Phytophthora root rot, Which will beuseful for reasonable and effective use of resistant resources. Main research results are asfollowed:Using 50 SSR makers analysis genetic diversity among soybean cultivars or lineswith resistance to P. sojae. Totally, 265 allelic variants were produced among thecultivars or lines with average 5.3 alleles per SSR locus. The SSR data were used tocompute Nei-Li similarity coeffients, and clustered by the unweighted pair group methodof arithmetic average (UPGMA). Average similarity coeffient is 0.3124, 88.9ï¼…ofsimilarity coeffient is between 0.2 and 0.4, and average PIC is 0.6756, it indicated thatsignificant genetic difference existed among the cultivars or lines.Based on the genetic similarity coefficient, the 166 cultivars or lines were dividedinto two groups when the coeffient was 0.28. When the coeffient was 0.33, the cultivarsor lines were divided into six groups. In many cases, the cultivars or lines with the samegeographical origin, and the same or similar resistance type to P. sojae were groupedclosely, they likely had the same or similar genetic backgroud and carried the sameresistant gene or resistant gene combination.the gerplasm from Northeast indicated more narrow genetic basement than thegerplasm from Huanghuaihai and South. Foreign cultivars Williams, Clark and its NILsmaybe a different gene pool from chinese cultivars, so it should be useful for wideningthe genetic basement.Four SSR markers linked to Rps genes were be used to identify the resistance gene, and the amplified results between NILs is not accord with its Rps gene, so the four makersare unavailable to identify the resistance gene in this research.