Abstract:Orange wheat blossom midge（OWBM，Sitodiplosis mosellana Géhin） is an important pest insect that seriously threatens wheat production. Cryptic habitat of OWBM lifecycle made pest control very difficult. Therefore，screening for OWBM-resistant wheat germplasm and tightly-linked molecular marker is of great important for pest control. In this study，566 wheat germplasm resources from different wheat regions and different periods，and genomic regions surrounding major OWBM locus were used to identify their resistance to OWBM，and to discover new SSR markers，respectively. The results showed that 27.03% of wheat cultivars were immune or highly resistant to OWBM，of which released in early years were still resistant to OWBM. Meanwhile，565 SSR markers were developed from the genomic region of major OWBM-resistant locus（Qsm.hbau-4A），and their detection efficiency were tested among this panel of wheat accessions. Of these SSR markers，marker Xhs87201bp showed robust PCR amplification and presented an average of 65.37% detection efficiency，and can be used for marker-assisted selection of OWBM resistance.

Abstract:Wheat blossom midge(Sitodiplosis mosellana Gehin)is one of the most important pests in wheat, which has caused large losses for wheat production and grain quality. Genetic analysis of wheat resistance to midge based on Quantitative trait locus (QTL) mapping and linked markers has important implications for improving the selection efficiency in breeding midge-resistant wheat. In this study, with recombinant inbred lines(RILs) derived from susceptible and resistant wheat lines as materials, we mapped the QTLs of midge resistance and characterized the relevant inheritance in Wheat cultivar Jimai 24 by using SSR markers and artificial midge nursery. The results showed that resistance between lines 6218 and Jimai 24 are significantly different, and resistance scales among RIL lines are stable during two consecutive years. A linkage map was constructed with 124 SSR loci, which comprises 24 linkage groups. The total length of this map was 672.8cM, and the average distance among different markers was 6.6cM. Using the IciMapping package for inclusive composite interval QTLmapping QTL, a QTL(QSm.hbau-4A) with additive effects was identified on 4A chromosome. The phenotypic variance explained (PVE) of this locus in the two test years is 9.67% and 10.57%, respectively. The mapping of this QTL and the identification of its linked SSR markers will increase the selection efficiency for breeding midge-resistant lines or cultivars.

Abstract:183 wheat varieties resistant to sitodiplosis mosellana were evaluated in the field. The results showed that there was significant difference among them in resistance of S. mosellana. Highly resistant, moderate resistant, low resistant, susceptible and highly susceptible varieties were 24.59%, 16.94, 18.58%, 14.21% and 25.68%, respectively. There was significant difference in ratio of damaged ear, damaged seed, and estimated damage of different wheat varieties. Among them, the highly resistant, moderate resistante varieties were 45 and 31, respectively. These wheat varieties were valuable as a main extention variety and reserved variety in occured area of S. mosellana or for breeding of resistance varieties.