Identification and genetic analysis of EMS-mutagenized wheat mutants conferring lesion-mimic premature aging

Lesion-mimic and premature aging (lmpa) mutant lmpa1 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 lmpa1 mutant, phenotypic observations and analyses of chlorophyll content and photosynthesis were carried out in lmpa1, KD527 and their F₁ and F₂ derivatives. Further, bulked segregation analysis (BSA) in combination with a 660 K SNP array were conducted on the F₂ segregation population of lmpa1/Chinese spring (CS) to locate the lmpa1 gene.

Most agronomic traits of lmpa1 were similar to those of KD527 before lesion-like spots appeared. Genetic analysis indicated that the F₁ plants from the crossing of lmpa1 and KD527 exhibited the lmpa phenotype and the F₂ progenies showed a segregation of normal (wild type, WT) and lmpa, with the ratios of lmpa: WT = 124:36(χ² = 1.008 < =3.841), indicating that lmpa is a dominant mutation. The combination of BSA and the SNP array analysis of CS, lmpa1 and lmpa1/CS F₂ WT pool (50 plants) and lmpa 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.

EMS-mutagenized mutant lmpa1 deriving from elite wheat line KD527 conferred lmpa. Lmpa phenotype of lmpa1 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.