StPBS2, a MAPK kinase gene, is involved in determining hyphal morphology, cell wall development, hypertonic stress reaction as well as the production of secondary metabolites in Northern Corn Leaf Blight pathogen Setosphaeria turcica

• Published in: Microbiological research 2017-08, Vol.201, p.30-38
• Main Authors: Gong, Xiao-dong, Feng, Sheng-ze, Zhao, Jie, Tang, Cong, Tian, Lan, Fan, Yong-shan, Cao, Zhi-yan, Hao, Zhi-min, Jia, Hui, Zang, Jin-ping, Zhang, Yun-feng, Han, Jian-min, Gu, Shou-qin, Dong, Jin-gao
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Ascomycota - cytology; Ascomycota - genetics; Ascomycota - growth & development; Ascomycota - metabolism; Cell Wall - metabolism; Cloning, Molecular; DNA, Fungal; Fungal Proteins - genetics; Fungal Proteins - metabolism; Fungal Proteins - physiology; Fungicides, Industrial - pharmacology; Gene Expression Regulation, Fungal; Gene Silencing; Genes, Fungal - genetics; Genes, Fungal - physiology; Glucose - metabolism; Hyphae - cytology; Hyphae - growth & development; MAPKK; Microscopy, Electron, Transmission; Mitogen-Activated Protein Kinase Kinases - classification; Mitogen-Activated Protein Kinase Kinases - genetics; Mitogen-Activated Protein Kinase Kinases - metabolism; Mitogen-Activated Protein Kinase Kinases - physiology; Morphogenesis - genetics; Osmotic Pressure - physiology; Phylogeny; Plant Diseases - microbiology; Real-Time Polymerase Chain Reaction; RNA Interference; RNAi; Secondary Metabolism - physiology; Sequence Alignment; Setosphaeria turcica; Spores, Fungal - cytology; Spores, Fungal - genetics; Spores, Fungal - growth & development; StPBS2; Zea mays - microbiology
• ISSN: 0944-5013; 1618-0623
• DOI: 10.1016/j.micres.2017.04.009

Mitogen activated protein kinase kinase (MAPKK) is a crucial component in the MAPK signaling pathway. However, the functions of MAPKKs in foliar pathogens remain poorly understood. In the current study, a MAPKK gene designated as StPBS2 was cloned from Setosphaeria turcica and the functions of this gene were investigated by RNAi technology. Four independent StPBS2 gene silence transformants with different efficiencies were confirmed by real time PCR. Compared to the wild type strain (WT), these transformants showed decreased colony growth, shortened hyphae cell length, broadened cell width and an obvious reduction in conidium yield. Moreover, the cell wall of the transformants was thicker and they were also more sensitive to substances that interfere with cell wall biosynthesis than WT. Additionally, the transformants displayed higher sensitivity to hypertonic stress than WT and the sensitivity was associated with the level of silencing of StPBS2. They were also resistant to the fungicides iprodione, procymidone and fludioxonil, to which WT almost completely sensitive. The transformants produced more red secondary metabolites than WT and the production was enhanced with increasing silencing level and increased glucose content in PDA medium. Our results suggest that StPBS2 is involved in morphogenesis, condiogenesis, cell wall development, hypertonic stress reaction and resistance to fungicides, as well as in the biosynthesis of secondary metabolites in S. turcica.