Genetic Mapping Of Aphid (Macrosiphum Avenae F.) Resistance Gene In Spring Wheat (Triticum Aestivum L.)

Wheat aphid(Homoptera: Aphididae) is one of the most important wheat (Triticum aestivium L.) pest all over the world. With the improvement of irrigation conditions on cornfield and changes of agricultural ecosystem, wheat aphid cause more losses than ever in wheat productivity. Nowadays, pest control and management heavily count on many chemical pesticides, however, the indiscriminate use of pesticides are toxic to beneficial insects, which act as predators or parasites to the pest species, and have a harmful effect on natural environment. It has been confirmed that the use of plant resistance as a pest management strategy is the most effective and economical method. It will be important theoretically and practically in the breeding processing if the Mechanism and Inheritance of the resistance to aphid were revealed and the resistant gene was further located and cloned.From 2003 to 2004, two resistance lines J-48 and J-31 to Macrosiphum avenae F. were screened out from 521 spring wheat germplasm by aphid field identification and aphid number ratio method (Shi guiying, 2006) and showed highly antibiosis by artificial infestation in 2005. Two lines J-48, J-31 and F1 hybrids resistance to aphid and two lines J-69, J-39 susceptible to aphid were employed in this experiment to study the Inheritance of the resistance to Macrosiphum avenae F., to look for molecular markers linked to aphid resistance gene through the analysis of F2 population. The main results are as follows:1. In heritance of wheat resistance to Macrosiphum avenae F.The analysis of F2 segregation population derived from the cross between J-31 and J-39 showed that the segregation ratio was corresponding with 3:1, the aphid resistance in J-31 is a quality inherit trait. The resistance to Macrosiphum avenae F. was controlled by a dominant major gene.The analysis of F2 segregation populations derived from the crosses ( J-48 x J-69 and J-48 x J-39) showed that both the segregation ratios were corresponding with 3:1, the aphid resistance in J-48 is a quality inherit trait. The resistance to Macrosiphum avenae F. was controlled by a dominant major gene.2. Molecular Marker linked with Wheat Resistance to Macrosiphum avenae F.BSA population constructed by cross of J-48 and J-69 was used in the experiment in order to look for markers linked with resistance gene. A total of 85 pairs of microsatellite primers uniform distribution on wheat chromosomes 7D and 1D were tested to detect polymorphisms between contrasting parents. 52 pairs of SSR primers were screened at the performance of polymorphism, polymorphism frequency is 61%. One SSR marker Xbarc126 linked with wheat resistance to Macrosiphum avenae F. had been found by BSA screening, the genetic distance was 15cM. Because this marker is located on chromosome 7D of wheat, therefore, Macrosiphum avenae F. resistance gene is located in the initial position on chromosome 7D of wheat and is named Ra temporarily.3. In the present study, a microsatellite (SSR) marker Xbarc126 linked to Macrosiphum avenae F. resistance gene Ra was identified using some F3 individuals derived from the cross of susceptible wheat cultivar J-48 and resistant source J-69, results showed the SSR marker Xbarc126 linked with resistance gene were existed. It provided microsatellite marker selected are stable, reliable and accurate molecular marker and reliable foundation for Molecular Marker Assisted Selection (MMAS).