Department of Biology, Utah State University, Logan, UT, USA.
J Appl Microbiol. 2010 Jan;108(1):115-28. doi: 10.1111/j.1365-2672.2009.04422.x.
The genetic relationships and conidial tolerances to high and low temperatures were determined for isolates of several Metarhizium species and varieties.
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 + or - 0.2 degrees 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 degrees 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).
Heat and cold exposures can be used as rapid tools to tentatively identify some important Metarhizium species and varieties.
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.
确定几种绿僵菌物种和变种的遗传关系和对高温和低温的分生孢子耐受性。
使用基于分子的技术（AFLP 和 rDNA（ITS1、ITS2 和 5.8S 基因测序））对来自广泛来源的形态鉴定的绿僵菌分离物进行了特征描述。将分离物的分生孢子悬浮液暴露于湿热（45±0.2°C）中，并在土豆葡萄糖琼脂加酵母提取物（PDAY）培养基上平板。暴露 8 小时后，分离物清楚地分为两组：（i）绿僵菌变种金龟子绿僵菌（Ma-an）和黄曲霉复合物中的绿僵菌（Mf）的所有分离物几乎没有分生孢子相对发芽率（RG），（ii）绿僵菌变种拟步甲绿僵菌（Ma-ac）分离物表现出高耐热性（约 70-100% RG）。将分生孢子悬浮液也平板于 PDAY 并在 5°C下孵育 15 天，在此期间 Ma-an 和 Ma-ac 分离物的 RG 几乎为零，而两个 Mf 具有高度耐寒性（100% RG）。
热和冷暴露可作为快速工具，暂时鉴定一些重要的绿僵菌物种和变种。
绿僵菌属的鉴定目前主要依赖于基于 DNA 的方法；我们建议使用简单的基于温度的筛选方法，快速获得对分离物作为种或种复合体的暂定鉴定。
