Identification of CmbHLH Transcription Factor Family and Excavation of Resistant to Necrotrophic Fungus in .

Ramat. 'Huaihuang' is a traditional Chinese medicinal plant. However, a black spot disease caused by sp., a typical necrotrophic fungus, has a serious damaging influence on the field growth, yield, and quality of the plant. 'Huaiju 2' being bred from 'Huaihuang', shows resistance to sp. bHLH transcription factor has been widely studied because of their functions in growth development, signal transduction, and abiotic stress. However, the function of bHLH in biotic stress has rarely been studied. To characterize the resistance genes, the CmbHLH family was surveyed in 'Huaiju 2'. On the basis of the transcriptome database of 'Huaiju 2' after sp. inoculation, with the aid of the genome database, 71 genes were identified and divided into 17 subfamilies. Most (64.8%) of the CmbHLH proteins were rich in negatively charged amino acids. CmbHLH proteins are generally hydrophilic proteins with a high aliphatic amino acid content. Among the 71 CmbHLH proteins, five were significantly upregulated by sp. infection, and the expression of was the most significant. Furthermore, heterologous overexpression of could improve the resistance of to necrotrophic fungus by enhancing callose deposition, preventing spores from entering leaves, reducing ROS accumulation, increasing the activities of antioxidant enzymes and defense enzymes, and promoting their gene expression levels. These results indicate that the five , especially , may be considered candidate genes for resistance to necrotrophic fungus. These findings not only increase our understanding of the role play in biotic stress but also provide a basis by using to breed a new variety of with high resistance to necrotrophic fungus.