Genetic Analysis Of Resistance To Heterodera Avenae In Wheat And Characterization Of Interaction Between Wheat Roots And H.filipievi

Cereal cyst nematode (CCN) has become a severe pathogenic nematode for wheat(Triticum aestivum L.) in recent years in China, which has seriously threaten food safety. Heterodera avenae and H. filipjevi are the major species of CCN that have limited wheat(Triticum aestivum) production in China. Planting resistant cultivars is the most economical, effective and environment-friendly measure to control CCN.Based on the results of field test and controlled environment test, we found that common wheat cultivar Taikong6was resistant to H. avenae populations from Zhengzhou, while Yumai47and Jimai1were susceptible. The F2populations of two crosses (Taikong6×Jimai1and Taikong6×Yumai47) were inoculated with juveniles of H. avenae in the greenhouse. The distributions of the number of white females per plant in each population exhibited the skewed normal distribution, which indicated that the resistance of Taikong6to H. avenae appeared to be a quantitative trait. The method of joint segregation analysis of single generation of major gene plus polygene mixed inheritance model was used to analyze the inheritance of resistance in Taikong6. The results showed that the genetic model B-1was the most fitted genetic model for the trait in the two crosses. This indicated that the resistance to CCN in Taikong6was controlled by two major genes with additive-dominant-epistasis effects plus polygenes effect. The major polygene heritabilities in F2were29.26%and32.50%, respectively.Heterodera filipjevi is a newly identified pathogenic species of cereal cyst nematode that invades wheat in central China. A two-year field test (2009-2011) conducted in Xuchang, Henan Province, China, where H. filipjevi has severely damaged wheat for several years, demonstrated that the wheat-rye(Secale cereale L.) chromosome substitution line6R(6D)(carrying gene CreR for resistance to Heterodera spp.) was highly resistant (HR) to the nematode. The wheat cultivar Taikong6was moderately resistant (MR) and its parental cultivar Yumai49was highly susceptible (HS). Attraction of H. filipjevi juveniles to root tips of wheats differed in resistance to H. filipjevi was studied using Pluronic F-127gel as a medium. Although root tips from wheat cultivars with different resistance were able to attract juveniles of nematode alone, the number of juveniles around the root tip from line6R(6D) was obviously less than that from Taikong6(MR) and Yumai49(HS) when they were challenged together concurrently by H. filipjevi. The juveniles were capable to penetrate into wheat roots regardless of their resistance as revealed by acid fuschin-sodium hypochlorite staining of infected roots. However, significantly smaller number of nematodes in the roots of6R(6D) and Taikong6were observed compared to those of Yumai49at later stage of wheat-H. filipjevi interaction. These findings demonstrate that some of the H. filipjevi juveniles are not able to continue to reproduce themselves although they can penetrate the roots of resistant wheat cultivars6R(6D) and Taikong6.