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

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.

Molecular, morphological and pathogenic characterization of six strains of Metarhizium spp. (Deuteromycotina: Hyphomycetes) for the control of Aegorhinus superciliosus (Coleoptera: Curculionidae)

“…The values of length and width are in the range described for M. anisopliae var. anisopliae (Bischoff et al, 2009;Fernandes et al, 2010). But, these results are not consistent with the molecular identification of isolate Qu-M171a, since according to Driver et al (2000) conidia of M. anisopliae var.…”

Thermotolerance of germlings and mycelium of the insect‐pathogenic fungus Metarhizium spp. and mycelial recovery after heat stress

“…The isolate ARSEF 324 is documented as having higher conidial UV-B and heat tolerance than other M. acridum isolates [7,8,27,28]. In addition, this isolate was more effective than other Metarhizium isolates in killing the grasshopper Phaulacridium vittatum at 35 °C [13].…”

“…40% after 36 h at 45 °C [8], being the most thermotolerant Metarhizium isolate described to date. The upper temperature limit for conidial germination or mycelial growth of Metarhizium sp.…”

Molecular characterization and evaluation of indigenous entomopathogenic fungal isolates against Sorghum Chafer, Pachnoda interrupta (Olivier) in Ethiopia

“…Fungi can be identified using morphological characteristics but this method is not adequate due to ambiguous descriptions and limited availability of morphological keys (Fernandes et al, 2010). However, the method can be used to minimize time and resource expenses when dealing with large number of isolates as a preliminary identification tool as employed in this study.…”