title: The seed dormancy allele TaSdr-A1a associated with pre-harvest sprouting tolerance is mainly present in Chinese wheat landraces.
abstract: We cloned TaSdr - A1 gene, and developed a gene-specific marker for TaSdr - A1 . A QTL for germination index at the TaSdr - A1 locus was identified in the Yangxiaomai/Zhongyou 9507 RIL population. Pre-harvest sprouting (PHS) affects yield and end-use quality in bread wheat (Triticum aestivum L.). In the present study we found an association between the TaSdr-A1 gene and PHS tolerance in bread wheat. TaSdr-A1 on chromosome 2A was cloned using a homologous cloning approach. Sequence analysis of TaSdr-A1 revealed an SNP at position 643, with the G allele being present in genotypes with lower germination index (GI) values and A in those with higher GI. These alleles were designated as TaSdr-A1a and TaSdr-A1b, respectively. A cleaved amplified polymorphism sequence (CAPS) marker Sdr2A based on the SNP was developed, and linkage mapping and QTL analysis were conducted to confirm the association between TaSdr-A1 and seed dormancy. Sdr2A was located in a 2.9 cM interval between SSR markers Xgwm95 and Xgwm372. A QTL for GI at the TaSdr-A1 locus explained 6.6, 7.3, and 8.2 % of the phenotypic variances in a Yangxiaomai/Zhongyou 9507 RIL population grown at Beijing, Shijiazhuang, and the averaged data from the two environments, respectively. Two sets of Chinese wheat cultivars used for validating the TaSdr-A1 polymorphism and the corresponding gene-specific marker Sdr2A showed that TaSdr-A1 was significantly associated with GI. Among 29 accessions with TaSdr-A1a, 24 (82.8 %) were landraces, indicating the importance of Chinese wheat landraces as sources of PHS tolerance. This study identified a novel PHS resistance allele TaSdr-A1a mainly presented in Chinese landraces and it is likely to be the causal gene for QPhs.ccsu-2A.3, providing new information for an understanding of seed dormancy.
authors.affiliation: Institute of Crop Science, National Wheat Improvement Center, Chinese Academy of Agricultural Sciences (CAAS), 12 Zhongguancun South Street, Beijing, 100081, China.|Institute of Cereal and Oil Crops, Hebei Academy of Agriculture and Forestry Sciences, 162 Hengshan Street, Shijiazhuang, 050035, China.
authors.forename: Yingjun
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Institute of Crop Science, National Wheat Improvement Center, Chinese Academy of Agricultural Sciences (CAAS), 12 Zhongguancun South Street, Beijing, 100081, China.
authors.forename: Xianchun
authors.initials: X
authors.lastname: Xia
authors.affiliation: Institute of Crop Science, National Wheat Improvement Center, Chinese Academy of Agricultural Sciences (CAAS), 12 Zhongguancun South Street, Beijing, 100081, China. zhhecaas@163.com.|International Maize and Wheat Improvement Center (CIMMYT) China Office, c/o CAAS, 12 Zhongguancun South Street, Beijing, 100081, China. zhhecaas@163.com.
authors.forename: Zhonghu
authors.initials: Z
authors.lastname: He
mesh_terms: D000483:Alleles; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D017343:Genes, Plant; D008040:Genetic Linkage; D005819:Genetic Markers; D005838:Genotype; D018525:Germination / Q000235:genetics*; D057445:Plant Dormancy / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci; D012639:Seeds / Q000235:genetics; D014908:Triticum / Q000235:genetics*
chemical_list: D005819:Genetic Markers