Identification of the resistance gene to powdery mildew in Chinese wheat landrace Baiyouyantiao

Powdery mildew, caused by Blumeria graminis f. sp. tritici （Bgt）, is one of the most damaging diseases to wheat in the world. The cultivation of resistant varieties of wheat is essential for controlling the powdery mildew epidemic. Wheat landraces are important resources of resistance to many diseases. Mapping powdery mildew resistance genes from wheat landraces will promote the development of new varieties with disease resistance. The Chinese wheat landrace Baiyouyantiao possesses characteristic of disease resistance to powdery mildew. To identify the resistance gene in this landrace, Baiyouyantiao was crossed with the susceptible cultivar Jingshuang 16 and seedlings of parents and F1, BC1, F2, and F~：3 were tested with Bgt isolate E09. The genetic results showed that the resistance of Baiyouyantiao to E09 was controlled by a single recessive gene, tentatively designated PmBYYT. An Illumina wheat 90K single-nucleotide polymorphism （SNP） array was applied to screen polymorphisms between F2-resistant and F2-susceptible DNA bulks for identifying the chromosomal location of PmBYYT. A high percentage of polymorphic SNPs between the resistant and susceptible DNA bulks was found on chro- mosome 7B, indicating that PmBYYT may be located on this chromosome. A genetic linkage map of PmBYYTconsisting of two simple sequence repeat markers and eight SNP markers was developed. The two flanking markers were SNP markers W7BL-8 and W7BL-15, with genetic distances of 3 and 2.9 cM, respectively. The results of this study demonstrated the rapid characterization of a wheat disease resistance gene and SNP marker development using the 90K SNP assay. The flanking markers of gene PmBYYTwill benefit marker-assisted selection （MAS） and map-based cloning in breeding wheat cultivars with powdery mildew resistance.

CAS Array:design and assessment of a genotyping array for Chinese biobanking

Background:Chronic diseases are becoming a critical challenge to the aging Chinese population.Biobanks with extensive genomic and environmental data offer opportunities to elucidate the complex gene-environment interactions underlying their aetiology.Genome-wide genotyping array remains an efficient approach for large-scale genomic data collection.However,most commercial arrays have reduced performance for biobanking in the Chinese population.Materials and methods:Deep whole-genome sequencing data from 2641 Chinese individuals were used as a reference to develop the CAS array,a custom-designed genotyping array for precision medicine.Evaluation of the array was performed by comparing data from 384 individuals assayed both by the array and whole-genome sequencing.Validation of its mitochondrial copy number estimating capacity was conducted by examining its association with established covariates among 10162 Chinese elderly.Results:The CAS Array adopts the proven Axiom technology and is restricted to 652429 single-nucleotide polymorphism(SNP)markers.Its call rate of 99.79% and concordance rate of 99.89% are both higher than for commercial arrays.Its imputation-based genome coverage reached 98.3% for common SNPs and 63.0% for low-frequency SNPs,both comparable to commercial arrays with larger SNP capacity.After validating its mitochondrial copy number estimates,we developed a publicly available software tool to facilitate the array utility.Conclusion:Based on recent advances in genomic science,we designed and implemented a high-throughput and low-cost genotyping array.It is more cost-effective than commercial arrays for large-scale Chinese biobanking.