Identification Of The Phytophthora Resistance Gene In Soybean Cultivars

Phytophthora root rot?PRR?caused by Phytophthora sojae is a devastating soybean disease worldwide,which has been spreading in China.Deployment of soybean cultivars resistant to Phytophthora is the most effective,economic and environmental friendly strategy to control the disease.1.Soybean cultivar Zheng 97196 is one of the main soybean cultivated cultivars,which has been widely planting in Huanghuai area.This cultivar has a broad spectrum resistant to P.sojae.The previous study identified a Phytophthora resistance gene RpsZheng in soybean cultivar Zheng 97196,which was mapped on chromosome 3.The objective of this study was to confirm and finely map the resistance gene RpsZheng.A 188 F_2:3 families derived from a cross of the susceptible Williams and resistant Zheng97196 were used as a mapping population.The genetic linkage map of RpsZheng was constructed using phenotypic and genotypic data.Firstly,using SSR markers on chromosome 3,Rps Zheng was furtherly mapped between the flanking markers SattWM82?39?2.5 cM?and BARCSOYSSR?03?0269?1.0 cM?.Then,we developed and identified polymorphic InDel markers from whole genome resequencing data of parents,and further narrow the RpsZheng candidate region to 105.2 kb.And the co-segregation markers of the RpsZheng were detected for specificity to RspZheng.To further verify the specificity of WZInDel11,the marker was used to detect 226 soybean cultivars with known phytophthora phenotypes.The result showed that the marker WZInDel11 could effectively distinguish RpsZheng from other Rps genes loci.The marker can be effectively used for molecular-assisted selection breeding and disease resistance gene function research.2.Henan Province is one of the main soybean producing area in China,which has a potential threat by Phytophthora root rot of soybean.The study was to screen effectively resistant cultivars for the disease control and resistance breeding.Sixty-four new soybean lines breeded in Henan were evaluated for their resistance responses to two P.sojae isolates PsJS2 and Ps41-1 using the hypocotyls inoculation technique.The result showed that 30 and 15 lines are resistance to Ps41-1and PsJS2,respectively.23and 13 lines are Intermediate to Ps41-1 and PsJS2,respectively.And there are 15 lines resistance to both Ps41-1 and PsJS2,accounting for 23.4%of the tested lines.The 64 lines was detected for Phytophthora resistance gene by using molecular marker WZInDel11 co-segregating with a resistance gene RpsZheng.The results show that,13 of 15 lines resistant to both PsJS2 and Ps41-1 contain target band of WZInDel11,while Luo 8825?Zhudou 37?Fandou 22 and Zheng 15234 resistant to isolates Ps41-1 and intermediate to PsJS2,and soybean line Luodou 8816 which showed intermediate reaction to two isolates show segregating to P.sojae produced heterozygous bands.Based on the results of marker detection and pedigree analysis,of 18 lines carrying marker WZInDel11,we speculated that Luo 8825and Luodou 8816 might contain the resistance gene RpsZheng,Zheng 15234 and Luodou 16106 might contain the resistance gene RpsYD29,other 14 lines might contain RpsZheng or alleles.All results showed that the new soybean lines breedd in Henan Province had high level of resistance to Phytophthora root rot and some lines could be used as excellent resistance sources.