Stress is the rule rather than the exception for Metarhizium
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The insect pathogenic plant root symbiont Metarhizium experiences many situations that restrict its growth whether living in host insects or on plant roots. These include a range of physical, chemical and biological effects involving UV and extremes of temperature, pH, nutrient availability, toxic metals and other pollutants, and insect host defenses such as production of reactive oxygen species. Aside virulence, the major impediment to reliable pest control with Metarhizium is its sensitivity to UV and temperature extremes. However, increased levels of stress tolerance can be engineered into Metarhizium quite simply by reprogramming the expression of single downstream endogenous genes. For example, overexpression of RNA-binding proteins resulted in Metarhizium with increased tolerance to cold stress, overexpression of photolyase increased tolerance to UV, and increased expression of heat shock protein 25 improved tolerance to several stress conditions, including heat, and osmotic pressure. Conversely, disruption of these genes greatly reduced persistence, and could provide genetic containment for genetically engineered hypervirulent strains.
KeywordsMetarhizium Stress response genes Heat shock Cold response UV stress Osmosensor Mitogen Activated protein (MAP) kinase pathway Colony deterioration Genetic engineering
The work reported here was supported in part by Biotechnology Risk Assessment Grant Program competitive Grant No. 2011-33522-30742 and by USDA CSREES Grant 2010-65106-20580 from the USDA National Institute of Food and Agriculture. This review article was supported in part by a grant from São Paulo Research Foundation (FAPESP) of Brazil #2014/01229-4.
- Chelico L, Haughian JL, Khachatourians GG (2006) Nucleotide excision repair and photoreactivation in the entomopathogenic fungi Beauveria bassiana, Beauveria brongniartii, Beauveria nivea, Metarhizium anisopliae, Paecilomyces farinosus and Verticillium lecanii. J Appl Microbiol 100:964–972. doi: 10.1111/j.1365-2672.2006.02844 PubMedCrossRefGoogle Scholar
- Gao Q, Jin K, Ying SH, Zhang Y, Xiao G, Shang Y, Duan Z, Hu X, Xie X, Zhou G, Peng G, Luo Z, Huang W, Wang B, Fang W, Wang S, Zhong Y, Ma L, St. Leger RJ, Zhao G, Pei Y, Feng M, Xia Y, Wang C (2011) Genome sequencing and comparative transcriptomics of the model entomopathogenic fungi Metarhizium anisopliae and M. acridum. PLoS Genet 7:e1001264. doi: 10.1371/journal.pgen.1001264 PubMedCentralPubMedCrossRefGoogle Scholar
- Kang SC, Bark YG, Lee DG, Kim YH (1996) Antifungal activities of Metarhizium anisopliae against Fusarium oxysporum, Botrytis cinerea, and Alternaria solani. Korean J MycolGoogle Scholar
- Liao X, O’Brien T, Fang W, St. Leger R.J (2014a) The plant beneficial effects of Metarhizium species correlate with their association with roots. Appl Microbiol Biotechnol. doi: 10.1007/s00253-014-5788-2 (Epub ahead of print)
- Yasui A, Eker APM (1997) DNA photolyases. In: Nickoloff JA, Hoekstra MF (eds) DNA damage and repair: biochemistry, genetics and cell biology. Humana Press, Totowa, pp 9–32Google Scholar
- Zhang Y, Zhao J, Fang W, Zhang J, Luo Z, Zhang M, Fan Y, Pei Y (2009) Mitogen-activated protein kinase hog1 in the entomopathogenic fungus Beauveria bassiana regulates environmental stress responses and virulence to insects. Appl Environ Microbiol 75:3787–3795PubMedCentralPubMedCrossRefGoogle Scholar