Diaoguo An: Genetic Improvement and Germplasm Enhancement in Wheat  

Molecular Cytogenetic Characterization of a New T2BL - 1RS Wheat-rye Chromosome Translocation Line Resistant to Stripe Rust and Powdery Mildew 

Diaoguo An, Chunmei Wang and Yunfeng Xu 

Wheat (Triticum aestivum) genotypes with rye (Secale cereale) 1RS chromosomal ranslocations are widely used in wheat breeding programs because 1RS carries genes for resistance to several diseases. However, some of the pathogens have evolved into new races that overcome the resistance due to the extensive use of cultivars with the resistance genes from rye. Therefore, identification and deployment of new resistance sources with desirable agronomic characteristics are important and urgent. We have used winter rye cultivar 'German White' as a source of genes for desirable traits in wheat improvement. A new genotype named WR04-32 was produced through hybridization and chromosome manipulation between common winter wheat cultivar 'Xiaoyan 6' and 'German White'. This genotype was highly resistant to a wide spectrum of the wheat stripe rust (Puccinia striiformis f. sp. tritici) and powdery mildew (Blumeria graminis f. sp. tritici) pathotypes prevalent in China (Table. 1). The PCR result using EST-STS marker STSWE126 specific to 1RS confirmed 1RS in WR04-32(Figure1) and it was further proved to be a wheat-rye T2BL？？1RS translocation line using sequential genomic in situ hybridization (GISH) and multi-color fluorescence in situ hybridization (FISH) with probes pAs1 and pSc119.2 (or pHvG38) (Figure2). In addition to its resistance to stripe rust and powdery mildew, WR04-32 was genetically stable and had desirable agronomic traits, ma king it a desirable germplasm for wheat breeding.