Characterization and Evaluation of Resistance to Powdery Mildew of Wheat- Roth 7M (7A) Alien Disomic Substitution Line W16998.

Roth has been used as a donor of disease-resistance genes, to enrich the gene pool for wheat () improvement through distant hybridization. In this study, the wheat- alien disomic substitution line W16998 was obtained from the BCF progeny of a cross between the common wheat 'Chinese Spring' (CS) and Roth (serial number: SY159//CS). This line was identified using cytogenetic techniques, analysis of genomic in situ hybridization (GISH), functional molecular markers (Expressed sequence tag-sequence-tagged site (EST-STS) and PCR-based landmark unique gene (PLUG), fluorescence in situ hybridization (FISH), sequential fluorescence in situ hybridization-genomic in situ hybridization (sequential FISH-GISH), and assessment of agronomic traits and powdery mildew resistance. During the anaphase of meiosis, these were evenly distributed on both sides of the equatorial plate, and they exhibited high cytological stability during the meiotic metaphase and anaphase. GISH analysis indicated that W16998 contained a pair of alien chromosomes and 40 common wheat chromosomes. One EST-STS marker and seven PLUG marker results showed that the introduced chromosomes of belonged to homoeologous group 7. Nullisomic-tetrasomic analyses suggested that the common wheat chromosome, 7A, was absent in W16998. FISH and sequential FISH-GISH analyses confirmed that the introduced chromosome was 7M. Therefore, W16998 was a wheat- 7M (7A) alien disomic substitution line. Inoculation of isolate E09 ( f. sp. ) in the seedling stage showed that SY159 and W16998 were resistant to powdery mildew, indeed nearly immune, whereas CS was highly susceptible. Compared to CS, W16998 exhibited increased grain weight and more spikelets, and a greater number of superior agronomic traits. Consequently, W16998 was potentially useful. Germplasms transfer new disease-resistance genes and prominent agronomic traits into common wheat, giving the latter some fine properties for breeding.