Somvanshi Vishal S, Koltai Hinanit, Glazer Itamar
Department of Nematology, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel.
Mol Biochem Parasitol. 2008 Mar;158(1):65-71. doi: 10.1016/j.molbiopara.2007.11.012. Epub 2007 Nov 26.
Entomopathogenic nematodes used as biological control agents encounter various stress conditions during extended periods in the soil. We investigated gene expression in nematodes that were tolerant or susceptible to desiccation stress to determine whether enhanced tolerance in these populations results from a 'gene-expression response' to desiccation or if, for enhanced tolerance, no such response is needed, perhaps due to a state of constant 'readiness'. The expressions of four genes, aldehyde dehydrogenase, nucleosome assembly protein 1, glutathione peroxidase and heat-shock protein 40, were characterized during desiccation stress in five entomopathogenic nematode species with differing stress tolerance: Steinernema feltiae strain IS-6, S. feltiae Carmiel strain, Steinernema carpocapsae Mexican strain, Steinernema riobrave, and Heterorhabditis bacteriophora strain TTO1. After 24h of desiccation, we observed an inverse relationship between expression of the studied genes and phenotypic desiccation-tolerance capability in the nematodes. H. bacteriophora TTO1 was most susceptible to desiccation but showed the highest expression of all studied genes under desiccation. S. carpocapsae Mexican strain and S. riobrave showed the lowest expression of these genes but were most tolerant to desiccation. Our study showed no induction of gene expression in stress-tolerant nematodes, whereas the stress-susceptible nematodes responded to stress by induced expression of these genes. Since the different levels of gene expression were found to be related to the different stress-tolerance capabilities of the nematodes, these gene-expression ratios can potentially be used as markers of desiccation tolerance in entomopathogenic nematodes.
用作生物防治剂的昆虫病原线虫在土壤中长期生存时会遇到各种胁迫条件。我们研究了对干燥胁迫具有耐受性或敏感性的线虫中的基因表达，以确定这些种群中增强的耐受性是源于对干燥的“基因表达反应”，还是对于增强的耐受性而言，可能由于持续的“准备就绪”状态而不需要这种反应。在五种具有不同胁迫耐受性的昆虫病原线虫物种（斯氏线虫属的斯氏线虫IS-6菌株、斯氏线虫卡尔米耶尔菌株、小卷蛾斯氏线虫墨西哥菌株、里奥布雷斯氏线虫和异小杆线虫属的嗜菌异小杆线虫TTO1菌株）的干燥胁迫过程中，对醛脱氢酶、核小体组装蛋白1、谷胱甘肽过氧化物酶和热休克蛋白40这四个基因的表达进行了表征。干燥24小时后，我们观察到所研究基因的表达与线虫的表型干燥耐受能力之间呈反比关系。嗜菌异小杆线虫TTO1对干燥最敏感，但在干燥条件下所有研究基因的表达最高。小卷蛾斯氏线虫墨西哥菌株和里奥布雷斯氏线虫这些基因的表达最低，但对干燥耐受性最强。我们的研究表明，耐胁迫线虫中没有基因表达的诱导，而胁迫敏感线虫通过这些基因的诱导表达对胁迫做出反应。由于发现不同水平的基因表达与线虫不同的胁迫耐受能力相关，这些基因表达比率有可能用作昆虫病原线虫干燥耐受性的标志物。
