Background: Lesion-mimic and premature aging ( lmpa ) mutant lm pa 1 was identified from the ethyl methane sulfonate (EMS) mutant library in the bread wheat variety Keda 527 (KD527) background. To reveal the genetic basis of l mpa 1 mutant, phenotypic observations and analyses of chlorophyll content and photosynthesis were carried out in l mpa 1 , KD527 and their F 1 and F 2 derivatives. Further, bulked segregation analysis (BSA) in combination with a 660K SNP Chip were conducted on the F 2 segregation population of l mpa 1 /Chinese spring(CS) to locate the l mpa 1 gene.
Results: Most agronomic traits of l mpa 1 were similar to those of KD527 before lesion-like spots appeared. Genetic analysis indicated that the F 1 plants from the crossing of l mpa 1 and KD527 exhibited the l mpa phenotype and the F 2 progenies showed a segregation of normal (wild type, WT) and l mpa , with the ratios of l mpa :WT=124:36（χ 2 =1.008<=3.841), indicating that l mpa is a dominant mutation. The combination of BSA and the SNP Chip analysis of CS, l mpa 1 and l mpa 1 /CS F 2 WT pool (50 plants) and l mpa pool (50 plants) showed that polymorphic SNPs were enriched on chromosome 5A, within a region of 30-40 Mb, indicating that the wheat premature aging gene Lmpa1 was probably located on the short arm of chromosome 5A.
Conclusions: EMS-mutagenized mutant lmpa 1 deriving from elite wheat line KD527 conferred lmpa . lmpa phenotype of l mpa 1 mutant is controlled by a single dominant allele designated as Lmpa1 , which affected wheat growth and development and reduced the thousand grain weight ( tgw ) of single plant in wheat. The gene Lmpa1 was tentatively located within the region of 30-40 Mb near to the short arm of chromosome 5A.