부산대학교 도서관

Natural alleles that control multiple disease resistance (MDR) are valuable for crop breeding. However, only one MDR gene has been cloned in maize, and the molecular mechanisms of MDR remain unclear in maize. In this study, through map-based cloning we cloned a teosinte-derived allele of a resistance gene, Mexicana lesion mimic 1 (ZmMM1), which causes a lesion mimic phenotype and confers resistance to northern leaf blight (NLB), gray leaf spot (GLS), and southern corn rust (SCR) in maize. Strong MDR conferred by the teosinte allele is linked with polymorphisms in the 3′ untranslated region of ZmMM1 that cause increased accumulation of ZmMM1 protein. ZmMM1 acts as a transcription repressor and negatively regulates the transcription of specific target genes, including ZmMM1-target gene 3 (ZmMT3), which functions as a negative regulator of plant immunity and associated cell death. The successful isolation of the ZmMM1 resistance gene will help not only in developing broad-spectrum and durable disease resistance but also in understanding the molecular mechanisms underlying MDR. In this study, the authors discover that ZmMM1 , encoding a MYB transcription factor, positively regulates maize resistance against NLB, GLS, and SCR by suppressing the transcription level of ZmMT3 , a negative regulator of reactive oxygen species (ROS) accumulation. The ZmMM1 allele from a teosinte line confers higher ZmMM1 protein levels, resulting in higher ROS levels and a stronger resistance phenotype than alleles from maize inbred lines. [ABSTRACT FROM AUTHOR]