Screening for differential expression of genes for resistance to Sitodiplosis mosellana in bread wheat via BSR-seq analysis.

KEY MESSAGE: Five putative candidate genes for OWBM resistance in Chinese winter wheat 'Jimai 24' were identified via BSR-seq and differential expression analyses. Orange wheat blossom midge (OWBM), Sitodiplosis mosellana, is one of the most serious threats to wheat production worldwide. Conventional gene mapping methods to identify genes require significant amounts of financial support and time. Here, bulked segregant RNA-seq (BSR-seq) was applied to profile candidate genes and develop associated markers for OWBM resistance. Previously, we identified a major QTL (QSm.hebau-4A) for OWBM resistance on the long arm of chromosome 4A. In this study, we aimed at screening differentially expressed resistance genes associated with this QTL. Twelve differentially expressed genes (DEGs) were obtained based on BSR-seq and differential expression analyses. Among them, four were confirmed to be associated with OWBM resistance via quantitative reverse transcription PCR, using an additional set of wheat samples subjected to OWBM invasion. One SPI-like gene and one Malectin-like gene were revealed by gene annotation, respectively. Sequencing results confirmed that the four DEGs and the SPI gene had SNP polymorphisms between wheat parents. All these five resistance-related genes for OWBM were located in the same genomic region with QSm.hebau-4A. Furthermore, six new markers developed based on sequences of the five genes were also mapped in the same genomic region using genetic population. These five genes may be the candidate genes for OWBM resistance in Chinese wheat 'Jimai 24' and should be the targets for further positional isolation.