Characterization of Metarhizium species and varieties based on molecular analysis, heat tolerance and cold activity

E.K.K. Fernandes; C.A. Keyser; J.P. Chong; D.E.N. Rangel; M.P. Miller; D.W. Roberts

doi:10.1111/j.1365-2672.2009.04422.x

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Characterization of Metarhizium species and varieties based on molecular analysis, heat tolerance and cold activity

E.K.K. Fernandes·C.A. Keyser·J.P. Chong·D.E.N. Rangel·M.P. Miller·D.W. Roberts

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Abstract

Aims: The genetic relationships and conidial tolerances to high and low temperatures were determined for isolates of several Metarhizium species and varieties. Methods and Results: Molecular-based techniques [AFLP and rDNA (ITS1, ITS2 and 5??8S) gene sequencing] were used to characterize morphologically identified Metarhizium spp. isolates from a wide range of sources. Conidial suspensions of isolates were exposed to wet heat (45 ?? 0??2??C) and plated on potato dextrose agar plus yeast extract (PDAY) medium. After 8-h exposure, the isolates divided clearly into two groups: (i) all isolates of Metarhizium anisopliae var. anisopliae (Ma-an) and Metarhizium from the flavoviride complex (Mf) had virtually zero conidial relative germination (RG), (ii) Metarhizium anisopliae var. acridum (Ma-ac) isolates demonstrated high heat tolerance (c. 70-100% RG). Conidial suspensions also were plated on PDAY and incubated at 5??C for 15 days, during which time RGs for Ma-an and Ma-ac isolates were virtually zero, whereas the two Mf were highly cold active (100% RG). Conclusions: Heat and cold exposures can be used as rapid tools to tentatively identify some important Metarhizium species and varieties. Significance and Impact of the Study: Identification of Metarhizium spp. currently relies primarily on DNA-based methods; we suggest a simple temperature-based screen to quickly obtain tentative identification of isolates as to species or species complexes. ?? 2009 The Society for Applied Microbiology.

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E.K.K. Fernandes, C.A. Keyser, J.P. Chong, D.E.N. Rangel, M.P. Miller, D.W. Roberts. 2010. Characterization of Metarhizium species and varieties based on molecular analysis, heat tolerance and cold activity. https://doi.org/10.1111/j.1365-2672.2009.04422.x

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