Resistance Inheritance Of Pepper Accession CM334 To Phytophthora Capsici And The Development Of Related Molecular Markers

Phytophthora capsici Leonian is one of the most devastating disease affecting the pepper production. Phytophthora capsici can cause damage to various organs of pepper plant and also plants in various growth period. The tremendous loss raised by the damping off in seedlings period is often destructive to the production.So the study of resistance inheritance in pepper seedlings and the increasing of disease resistance of pepper seedling is extremely important.Different researchers concluded diverse conclusionon on the resistance inheritance even to the same resistance accession.One of these important factors affect the analysis is the distinct pathogenic mechanisms of the Phytophthora capsici.We studied the resistance inheritance of resistant accession CM334 by using two different races of Phytophthora capsici,and developed two markers associated with disease resistance by making use of the resistance gene analogue (RGA). The main results are as follows:We studied the resistance inheritance of the pepper material CM334 by using resistance material CM334,susceptible material EC and the hybrids of the two accessions,F1and F2 generation.And two different physiological races of Phytophthora capsici Ph1, Ph2 was used as the pathogen.The resistance analysis was conducted by irrigating the seedling with spore suspension of the two physiological races respectively.The chi-square test was used to test the segregation proportion of the F2 segregating populations.Results showed that,the CM334 resistance inheritance in line with the single dominant genetic model in both vaccination of Ph1 and Ph2 races,although the pathogenicity of the two races vary.At present study, We desined a pair of PCR primers by using a full-length disease resistance gene analog "RGA1"(GenBank accession No. GQ386945), cloned by our research group.We screened the high resistant accession CM334 and susceptible accesion EC with this PCR primers.Consequently, we get a 700bp band (STS700) in the highly resistant accession CM334, and can not get it in susceptible EC.Furthermore, we checked this STS700 marker with several other susceptible materials to Phytophthora capsici.STS700 marker exists only in highly resistant materials CM334,not in the susceptible ones.So,we speculated that this marker related with Phytophthora capsici resistance in pepper.We developed a pair of primers, based on another the full-length disease resistance genes analogues(RGA2) ,cloned and released by our research group.Polymorphic application was conducted between CM334, an extremely resistant accession to Phytophthora capsici and Early Calwonder (EC),a highly susceptible accession to Phytophthora capsici,and obtain a co-dominant RGA-STS1200 marker. We checked the polymorphism of the RGA-STS1200 marker in three pepper accessions,CM334,PBC459 and PBC137-1,which obtain resistance to different Phytophthora capsici races,as well three susceptible species EC,"qiemen"and B2. Results showed that,the three resistance accessions possess the same band and the three susceptible species own the same band.This applied that the STS1200 marker related to the resistance and can be used in distinguishing resistant or susceptible of pepper species to Phytophthora capsici.