Physiological disorder caused by gene mutations in plants could result in lesion mimics(LMs).Plants with LMs have a phenotype similar to those with programmed cell death(PCD)invoked by pathogens and are thus used in the investigation of mechanisms underlying PCD.To identify new genes involved in PCD,two wheat LM mutants,Met0187 and Mfh0014,were characterized.These two mutants were obtained from a tetraploid wheat treated with ethylmethyl sulfide(EMS)and fiom a hexaploid wheat with dry seeds irradiated with fast neutrons,respectively.They exhibited spontaneous lesions,around which H2O2 accumulation and autofluorescence were detected or observed.The necrotic phenotype was temperature-sensitive and appeared only when the plants were grown under 16℃ condition and not when grown under conditions above 20℃.Three examined PCD marker genes showed differential expression patterns between the wild and mutant genotypes,indicating that Met0187 and Mfh0014 were PCD-related mutants.Other than the necrotic phenotype,dwarfing was also observed for the mutants.Exogenous GA3 application restored the mutants height.Genes involved in the GA biosynthesis pathway displayed lower expression level,suggesting that GA biosynthesis was compromised in Met0187 and Mfh0014.Genetic analysis indicated that a single recessive gene mutation caused the mutant phenotype in both Met0187 and Mfh0014.The mutated genes were mapped to homologous intervals of chromosomes 6A and 6B,respectively,implying they are orthologs.