title: Interplay between calcineurin and the Slt2 MAP-kinase in mediating cell wall integrity, conidiation and virulence in the insect fungal pathogen Beauveria bassiana.
abstract: The entomopathogenic fungus, Beauveria bassiana, is of environmental and economic importance as an insect pathogen, currently used for the biological control of a number of pests. Cell wall integrity and conidiation are critical parameters for the ability of the fungus to infect insects and for production of the infectious propagules. The contribution of calcineurin and the Slt2 MAP kinase to cell wall integrity and development in B. bassiana was investigated. Gene knockouts of either the calcineurin CNA1 subunit or the Slt2 MAP kinase resulted in decreased tolerance to calcofluor white and high temperature. In contrast, the Δcna1 strain was more tolerant to Congo red but more sensitive to osmotic stress (NaCl, sorbitol) than the wild type, whereas the Δslt2 strain had the opposite phenotype. Changes in cell wall structure and composition were seen in the Δslt2 and Δcna1 strains during growth under cell wall stress as compared to the wild type. Both Δslt2 and Δcna1 strains showed significant alterations in growth, conidiation, and viability. Elevation of intracellular ROS levels, and decreased conidial hydrophobicity and adhesion to hydrophobic surfaces, were also seen for both mutants, as well as decreased virulence. Under cell wall stress conditions, inactivation of Slt2 significantly repressed CN-mediated phosphatase activity suggesting some level of cross talk between the two pathways. Comparative transcriptome profiling of the Δslt2 and Δcna1 strains revealed alterations in the expression of distinct gene sets, with overlap in transcripts involved in cell wall integrity, stress response, conidiation and virulence. These data illustrate convergent and divergent phenotypes and targets of the calcineurin and Slt2 pathways in B. bassiana.
authors: College of Plant Protection, Biotechnology Research Center, Southwest University, Chongqing 400715, People's Republic of China.
authors: Shuaishuai
authors: S
authors: Huang
authors: College of Plant Protection, Biotechnology Research Center, Southwest University, Chongqing 400715, People's Republic of China.
authors: Zhangjiang
authors: Z
authors: He
authors: College of Plant Protection, Biotechnology Research Center, Southwest University, Chongqing 400715, People's Republic of China.
authors: Shiwei
authors: S
authors: Zhang
authors: Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA.
authors: Nemat O
authors: NO
authors: Keyhani
authors: College of Plant Protection, Biotechnology Research Center, Southwest University, Chongqing 400715, People's Republic of China.
authors: Yulin
authors: Y
authors: Song
authors: College of Plant Protection, Biotechnology Research Center, Southwest University, Chongqing 400715, People's Republic of China.
authors: Zhi
authors: Z
authors: Yang
authors: College of Plant Protection, Biotechnology Research Center, Southwest University, Chongqing 400715, People's Republic of China.
authors: Yahui
authors: Y
authors: Jiang
authors: Medical Research Center, North China University of Science and Technology, Hebei 06000, People's Republic of China.
authors: Wenli
authors: W
authors: Zhang
authors: College of Plant Protection, Biotechnology Research Center, Southwest University, Chongqing 400715, People's Republic of China.
authors: Yan
authors: Y
authors: Pei
authors: College of Plant Protection, Biotechnology Research Center, Southwest University, Chongqing 400715, People's Republic of China. Electronic address: yjzhang@swu.edu.cn.
authors: Yongjun
authors: Y
authors: Zhang
mesh_terms: D000818:Animals; D052982:Beauveria / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity*; D019703:Calcineurin / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism; D004271:DNA, Fungal / Q000235:genetics; D005656:Fungal Proteins / Q000378:metabolism*; D006358:Hot Temperature; D025301:Hyphae / Q000166:cytology / Q000254:growth & development; D007313:Insecta / Q000382:microbiology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009997:Osmotic Pressure / Q000502:physiology; D013172:Spores, Fungal; D013312:Stress, Physiological; D014774:Virulence
chemical_list: D004271:DNA, Fungal; D005656:Fungal Proteins; D020928:Mitogen-Activated Protein Kinases; D019703:Calcineurin
keywords: Beauveria bassiana; Calcineurin; Cell wall integrity; Conidiation; Slt2 MAP kinase; Virulence