Polymorphism of TaSAP1-A1 and its association with agronomic traits in wheat

TaSAP, a member of the stress association protein (SAP) gene family from wheat, is involved in response to several abiotic stresses, including drought, salt and cold. In this study, TaSAP-A1, a TaSAP1 member on chromosome 7A, and its flanking sequences were isolated. Polymorphism analysis indicated that the average nucleotide diversity (π) of the whole region was 0.00296. The highest nucleotide diversity occurred in the promoter region (π = 0.00631) and no polymorphism was identified in the coding region. Three markers T7AM5, T7AM2606 and T7AM39 located in the promoter region, were developed from sequence variations (InDe15-1810, SNP-2606 and InDe139-1637). Six haplotypes were identified among 300 accessions based on the three markers. TaSAP1-A1 was located on chromosome 7A using marker T7AM39 and was flanked by markers Xwmc530 and Xbarc174. QTL for yield-related traits, including 1,000-grain weight, number of grains per spike and grain yield, were located in the same region. In marker- and haplotype-trait association analyses, TaSAP1-A1 was significantly associated with 1,000-grain weight, number of grains per spike, spike length, peduncle length and total number of spikelets per spike in multiple environments. These results provide useful information for marker-assisted selection for yield-related traits under well-watered and drought-stressed conditions.