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 Our research topics include gene functional studies of entomopathogenic fungi, fungi-insect molecular interactions, mechanism exploration of fungal degeneration and the developmental biology of Cordyceps spp.
Pricipal Investigator: Dr. Cheng-Shu Wang, Professor. Email: cswang@sibs.ac.cn
Staff: Shao-Hua Shi, Ding-Ding Lv, Research Interns
Graduate Students: Zhi-Bing Duan; Lin Li; Peng Zheng; Cheng-Hui Xiong; Xiao Hu; Yong-Liang Xia; Qiang Gao; Yan-Fang Shang; Wei Huang
Joint Graduate Student: Yuan-Yuan Ning (Fujian Agriculture and Forestry University)
The MOS1 Osmosensor of Metarhizium anisopliae is Required for Adaptation to Insect Host Hemolymph
Entomogenous fungi infect insects by direct penetration of the cuticle, after which the fungus adapts to the high osmotic pressure of the hemolymph and multiplies. Here we characterize the M. anisopliae Mos1 gene, and demonstrate that it encodes the osmosensor required for this process. Transformants containing an antisense vector directed to the Mos1 mRNA depleted transcript levels by 80%. Consistent with a role in stress responses, transcript depletion of Mos1 increased sensitivity to osmotic and oxidative stresses. It also disrupted developmental processes including formation of appressoria and hyphal bodies. Insect bioassays confirmed that Mos1 knockdown significantly reduces virulence.
Associated Links Among mtDNA Glycation, Oxidative Stress and Colony Sectorization in Metarhizium anisopliae
Mycelial colonies of filamentous fungi often deteriorate when maintained on artificial media. In this study we demonstrate that: 1) H2O2 increases rates of sectorization; 2) a stable strain of M. anisopliae eliminates intracellular ROS more rapidly than an unstable strain; 3) mitochondrial DNA from sectors undergoes a non-enzymatic glycation of deoxyguanosine; 4) the membrane potential of mitochondria in sector cells is decreased in comparison to wild type cells indicating loss of function; 5) DNA glycation changes the properties of DNA, and 6) treating wild type mycelia with H2O2 reproduced the glycation pattern shown in sectors. Fungal sectorization thus displays aging related developmental impairments resulting from oxidative stress, suggesting a new research direction for studies on fungal colony deterioration.
Insecticidal Evaluation of Beauveria bassiana Engineered to Express a Scorpion Neurotoxin and a Cuticle Degrading Protease
To improve the insecticidal efficacy of the entomopathogen Beauveria bassiana, the fungus was genetically modified with an insect-specific scorpion neurotoxin AAIT and an insect cuticle degrading protease PR1A. In comparison to the wild type strain, engineered isolates took fewer spores to kill 50 % of pine caterpillars, 15-fold less for the aaIT single transformant Bb13T and 8-fold less for the double transformant Bb13TPR1A, respectively. The median lethal times for Bb13T and Bb13TPR1A were reduced by 40 % and 36.7 %, respectively against D. punctatus, and 24.4 % and 20.9 %, respectively against G. mellonella. Our data showed that the co-transformation of these two genes produced no synergistic effects on virulence improvement.
Publications:
Wang CS*, Duan ZB and St Leger RJ. (2008) The MOS1 osmosensor of Metarhizium aniso- pliae is required for adaptation to insect host hemolymph. Eukaryotic Cell 7: 302-309. Li L, Pischetsrieder M, St. Leger RJ, Wang CS*. (2008) Associated links among mtDNA glycation, oxidative stress and colony sectorization in Metarhizium aniso- pliae. Fungal Genetics and Biology 45: 1300-1306. Lv DD, Pava-Ripoll M, Li Z Z, Wang CS*. (2008) Insecticidal evaluation of Beauveria bassiana engineered to express a scorpion neurotoxin and a cuticle degrading protease. Applied Microbiology and Biotechnology 81: 515-522. Pava-Ripoll M, Posada FJ, Momen B, Wang CS, St Leger RJ. (2008) Increased pathogenicity against coffee berry borer, Hypothe- nemus hampei (Coleoptera: Curcul- ionidae) by Metarhizium anisopliae expressing the scorpion toxin (AaIT) gene. Journal of Invertebrate Pathology 99: 220-226. Bao YY, Li MW, Zhao YP, Ge JQ, Wang CS, Huang YP, Zhang CX. (2008) Differentially expressed genes in resistant and susceptible Bombyx mori strains infected with a denso- nucleosis virus. Insect Biochemistry and Molecular Biology 38: 853-861. 吕丁丁, 李增智, 王成树*. (2008) 虫生真菌分子致病机理与基因工程改造研究进展. 微生物学通报 35: 443-449.
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