Laboratório de Microbiologia do Solo, ICAAM, Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Universidade de Évora, Evora, Portugal.
Antonie Van Leeuwenhoek. 2011 Mar;99(3):651-62. doi: 10.1007/s10482-010-9539-9. Epub 2010 Dec 9.
The symbiosis between rhizobia and legumes is affected by different environmental conditions. Our aims were to evaluate stress tolerance of Mesorhizobium species and investigate species-specific stress response mechanisms. Tolerance of Mesorhizobium type strains to temperature, salt and pH stress was evaluated. Mesorhizobium thiogangeticum showed highest growth with 1.5% NaCl and Mesorhizobium ciceri at pH 5. Mesorhizobium plurifarium showed higher growth at 37°C. SDS-PAGE analysis revealed changes in the protein profiles, namely the overexpression of a 60 kDa protein, following heat stress. Under salt stress, five overexpressed proteins were identified in M. plurifarium and M. thiogangeticum. Northern analysis revealed an increase in groEL expression in Mesorhizobium huakuii and Mesorhizobium septentrionale after heat shock; by contrast, a decrease was detected in Mesorhizobium albiziae and M. thiogangeticum, upon salt shock. A high diversity in tolerance to temperature, salt and pH stress was detected among Mesorhizobium species. M. thiogangeticum and M. ciceri are moderately halophilic and acidophilic, respectively. Several proteins, overproduced in different strains, may be involved in stress tolerance. groEL expression increased upon heat and decreased upon salt shock. To our knowledge, this is the first study focusing tolerance to temperature, salt and pH stress, as well as groEL expression, in Mesorhizobium type strains.
根瘤菌与豆科植物的共生关系受到不同环境条件的影响。我们的目的是评估中慢生根瘤菌属物种的抗逆性，并研究其特定的应激响应机制。评估了中慢生根瘤菌型菌株对温度、盐度和 pH 值胁迫的耐受性。Mesorhizobium thiogangeticum 在 1.5%NaCl 中生长最好，Mesorhizobium ciceri 在 pH5 下生长最好。Mesorhizobium plurifarium 在 37°C 下生长最好。SDS-PAGE 分析显示，热胁迫后蛋白质图谱发生变化，即 60kDa 蛋白表达上调。在盐胁迫下，M. plurifarium 和 M. thiogangeticum 中鉴定出 5 种过表达蛋白。Northern 分析显示，热激后 Mesorhizobium huakuii 和 Mesorhizobium septentrionale 中 groEL 表达增加；相反，盐激后 Mesorhizobium albiziae 和 M. thiogangeticum 中 groEL 表达减少。中慢生根瘤菌属物种对温度、盐度和 pH 值胁迫的耐受性存在高度多样性。M. thiogangeticum 和 M. ciceri 分别为中度嗜盐和嗜酸。一些在不同菌株中过表达的蛋白可能参与了抗逆性。groEL 表达在热激时增加，盐激时减少。据我们所知，这是首次研究中慢生根瘤菌型菌株对温度、盐度和 pH 值胁迫以及 groEL 表达的耐受性。
