title: Primary roles of two dehydrogenases in the mannitol metabolism and multi-stress tolerance of entomopathogenic fungus Beauveria bassiana.
abstract: Knockout and complement mutants of mannitol-1-phosphate dehydrogenase (MPD) and mannitol dehydrogenase (MTD) were constructed to probe the roles of both enzymes in the mannitol metabolism and multi-stress tolerances of entomopathogenic fungus Beauveria bassiana. Compared with wild-type and complement mutants, ΔBbMPD lost 99.5% MPD activity for reducing fructose-6-phosphate to mannitol-1-phosphate while ΔBbMTD lost 78.9% MTD activity for oxidizing mannitol to fructose. Consequently, mannitol contents in mycelia and conidia decreased 68% and 83% for ΔBbMPD, and 16% and 38% for ΔBbMTD, accompanied by greatly enhanced trehalose accumulations due to 81-87% decrease in their neutral trehalase expression. Mannitol as mere carbon source in a nitrate-based minimal medium suppressed the colony growth of ΔBbMTD instead of ΔBbMPD, and delayed more conidial germination of ΔBbMTD than ΔBbMPD. Based on median lethal responses, conidial tolerances to H(2) O(2) oxidation, UV-B irradiation and heat stress at 45°C decreased 38%, 39% and 22% in ΔBbMPD, and 18%, 16% and 11% in ΔBbMTD respectively. Moreover, ΔBbMPD and ΔBbMTD lost 14% and 7% of their virulence against Spodoptera litura larvae respectively. Our findings highlight the primary roles of MPD and MTD in mannitol metabolism and their significant contributions to multi-stress tolerances and virulence influential on the biocontrol potential of B.bassiana.
authors: Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
authors: Zheng-Liang
authors: ZL
authors: Wang
authors: Jiang-dong
authors: JD
authors: Lu
authors: Ming-Guang
authors: MG
authors: Feng
mesh_terms: D000818:Animals; D052982:Beauveria / Q000187:drug effects / Q000201:enzymology* / Q000472:pathogenicity / Q000528:radiation effects; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D005816:Genetic Complementation Test; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008353:Mannitol / Q000378:metabolism*; D008354:Mannitol Dehydrogenases / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D025282:Mycelium / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology; D018411:Spodoptera / Q000382:microbiology; D013172:Spores, Fungal / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D013312:Stress, Physiological / Q000502:physiology*; D013401:Sugar Alcohol Dehydrogenases / Q000235:genetics / Q000378:metabolism*; D014466:Ultraviolet Rays; D014774:Virulence / Q000235:genetics
chemical_list: D016877:Oxidants; D008353:Mannitol; D006861:Hydrogen Peroxide; D008354:Mannitol Dehydrogenases; D013401:Sugar Alcohol Dehydrogenases; C021544:mannitol-1-phosphate dehydrogenase