Contributions of β-tubulin to cellular morphology, sporulation and virulence in the insect-fungal pathogen, Metarhizium acridum.
β-tubulin is an elementary subunit of microtubules that form the cytoskeleton, participating in a wide range of cellular processes. The contributions of the single β-tubulin gene in affecting cell morphology, sporulation and virulence were examined in the entomopathogenic fungus Metarhizium acridum. Targeted gene knockout of β-tubulin resulted in resistance to benomyl but impaired proper nuclear segregation, lipid droplet transport, and deposition of chitin to the cell wall. M. acridum β-tubulin mutants displayed wavy hyphal growth and densely packed, wrinkled colonies. Decreases in the rate of phialides formation and conidial yield were observed for the β-tubulin mutant, which was also impaired in virulence towards locust hosts as compared to wild type and complemented strains. Morphological analyses of infection structures revealed development of bifurcated germ tubes, with reduced appressoria formation seen in the β-tubulin mutant. M. acridum β-tubulin mutant appressoria were aberrant in morphology and displayed decreased turgor pressure. The ability of the M. acridum β-tubulin mutant to proliferate in the insect hemolymph both in vitro and in vivo was also significantly reduced. Our results indicate that in M. acridum, β-tubulin is not essential for survival but that it contributes to cellular transport of organelles and cell wall materials, impacting growth, appressorial differentiation, virulence, and sporulation.
Genetic Engineering Research Center, School of Life Science, Chongqing University, Chongqing 400030, PR China; Chongqing Engineering Research Center for Fungal Insecticide, Chongqing 400030, PR China; Key Laboratory of Gene Function and Regulation Technologies under Chongqing Municipal Education Commission, Chongqing 400030, PR China. Electronic address: zhangjiezk@qq.com.
Jie
J
Zhang
Genetic Engineering Research Center, School of Life Science, Chongqing University, Chongqing 400030, PR China; Chongqing Engineering Research Center for Fungal Insecticide, Chongqing 400030, PR China; Key Laboratory of Gene Function and Regulation Technologies under Chongqing Municipal Education Commission, Chongqing 400030, PR China. Electronic address: jinkai@cqu.edu.cn.
Kai
K
Jin
Genetic Engineering Research Center, School of Life Science, Chongqing University, Chongqing 400030, PR China; Chongqing Engineering Research Center for Fungal Insecticide, Chongqing 400030, PR China; Key Laboratory of Gene Function and Regulation Technologies under Chongqing Municipal Education Commission, Chongqing 400030, PR China. Electronic address: yuxianxia@cqu.edu.cn.
Yuxian
Y
Xia
D000818:Animals; D015966:Gene Expression Regulation, Fungal; D007313:Insecta / Q000382:microbiology; D052981:Metarhizium / Q000235:genetics* / Q000472:pathogenicity; D013172:Spores, Fungal / Q000235:genetics* / Q000254:growth & development; D014404:Tubulin / Q000235:genetics*
D014404:Tubulin
Cell transport; Entomopathogenic fungi; Metarhizium acridum; Microtubule; Virulence; β-tubulin