Cardoso Paulo, Freitas Rosa, Figueira Etelvina
Departamento de Biologia, Universidade de Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal,
Ecotoxicology. 2015 Jan;24(1):143-52. doi: 10.1007/s10646-014-1366-8. Epub 2014 Oct 16.
It is predicted that global climate change may alter environmental parameters such as rainfall distribution which in turn may alter the salinity of soils with unpredictable effects upon soil microbial populations. In the present work the tolerance to salinity of rhizobia, isolated from locations with contrasting climatic conditions, and the potential of strains to fix nitrogen symbiotically under saline conditions were investigated. Since plasmids may encode key genes related to growth and survival under environmental stress conditions, which will reflect on protein synthesis, both the plasmid and protein profiles were analyzed. A multivariate statistical approach related salt tolerance to the origin of the isolates, identifying rainfall and water availability as a possible factor explaining the differences in salt tolerance displayed by rhizobia isolates. The classification analysis allowed the subdivision of isolates in terms of salt tolerance into extremely sensitive (≤0.15 %), sensitive (0.15-0.6 %), moderately tolerant (0.9-1.5 %), tolerant (2.1-3.6 %) and extremely tolerant (≥5.4 %). Taken all together it was shown that plasmids are involved in salt tolerance and that the impact of salinity on the protein profile and nitrogen fixation varied according to the salt tolerance of the strains, evidencing the susceptibility of rhizobial communities to changes in rainfall regimes.
据预测，全球气候变化可能会改变降雨分布等环境参数，进而改变土壤盐分，对土壤微生物种群产生不可预测的影响。在本研究中，对从气候条件不同的地点分离出的根瘤菌的耐盐性，以及菌株在盐胁迫条件下共生固氮的潜力进行了研究。由于质粒可能编码与环境胁迫条件下生长和存活相关的关键基因，这会反映在蛋白质合成上，因此对质粒和蛋白质谱进行了分析。一种多变量统计方法将耐盐性与分离株的来源相关联，确定降雨和可用水量是解释根瘤菌分离株耐盐性差异的一个可能因素。分类分析允许根据耐盐性将分离株细分为极敏感（≤0.15%）、敏感（0.15 - 0.6%）、中度耐受（0.9 - 1.5%）、耐受（2.1 - 3.6%）和极耐受（≥5.4%）。综合来看，结果表明质粒与耐盐性有关，并且盐分对蛋白质谱和固氮的影响因菌株的耐盐性而异，这证明了根瘤菌群落对降雨模式变化的敏感性。
