Transcriptome analysis of Dlm mutants reveals the potential formation mechanism of lesion mimic in wheat

Previous investigations demonstrated that Chinese wheat cv. Ning7840 confers a high level of broad-spectrum resistance to rusts and powdery mildew diseases at the adult plant stage mediated by a spontaneously occurring hypersensitive reaction-like phenotype (also called lesion mimic, LM). In this study, two EMS-induced mutants of cv. Ning7840, Dlm1 and Dlm2 , showed the LM deficiency phenotype. These two mutants were susceptible to powdery mildew. At heading stage when the LM symptoms appear on the leaves of Ning7840, the RNAs were harvested from the flag leaves of Dlm1 , Dlm 2 and Ning7840 leaves and were sequenced to decipher the molecular mechanisms underlying LM phenotypes. The results suggest that the diterpenoid-related stress response acts as an indirect regulator of the LM phenotype and may be associated with broad-spectrum resistance in Ning7840. Oxidative phosphorylation, proteasome, and chlorophyll were involved in the suppression of the LM expression in the Dlm mutants. These results provide new insight into the molecular mechanism of LM and broad-spectrum resistance in wheat.