Plant Biotechnology Laboratory, Department of Biochemistry and Molecular Biology, University of Dhaka, Dhaka, Bangladesh.
Department of Biochemistry and Biotechnology, University of Barishal, Barishal, Bangladesh.
Folia Microbiol (Praha). 2023 Feb;68(1):55-72. doi: 10.1007/s12223-022-00997-y. Epub 2022 Aug 1.
Halotolerant bacteria get adapted to a saline environment through modified physiological/structural characteristics and may provide stress tolerance along with enhanced growth to the host plants by different direct and indirect mechanisms. This study reports on multiple halotolerant plant growth-promoting rhizobacteria isolated from the coastal soils in Bangladesh, in fields where the halophytic wild rice Oryza coarctata is endemic. The aim was to find halotolerant bacteria for potential use as biofertilizer under normal/salt-stressed conditions. In this study, eight different strains were selected from a total of 20 rhizobacterial isolates from the saline-prone regions of Debhata and Satkhira based on their higher salt tolerance. 16S rRNA gene sequencing results of the rhizobacterial strains revealed that they belonged to Halobacillus, Bacillus, Acinetobactor, and Enterobactor genera. A total of ten halotolerant rhizobacteria (the other 2 bacteria were previously isolated and already reported as beneficial for rice growth) were used as both single inoculants and in combinations and applied to rice growing in pots. To investigate their capability to improve rice growth, physiological parameters such as shoot and root length and weight, chlorophyll content at the seedling stage as well as survival and yield at the reproductive stage were measured in the absence or presence (in concentration 40 or 80 mmol/L) of NaCl and in the absence or presence of the rhizobacteria. At the reproductive stage, only 50% of the uninoculated plants survived without setting any grains in 80 mmol/L NaCl in contrast to 100% survival of the rice plants inoculated with a combination of the rhizobacteria. The combined halotolerant rhizobacterial inoculations showed significantly higher chlorophyll retention as well as yield under the maximum NaCl concentration applied compared to application of single species. Thus, the use of a combination of halotolerant rhizobacteria as bioinoculants for rice plants under moderate salinity can synergistically alleviate the effects of stress and promote rice growth and yield.
耐盐细菌通过改变生理/结构特性来适应盐环境，通过不同的直接和间接机制为宿主植物提供应激耐受和增强生长。本研究报告了从孟加拉国沿海土壤中分离出的多种耐盐植物促生根瘤菌，这些土壤分布在特有耐盐野生稻 Oryza coarctata 的田地中。目的是找到耐盐细菌，以便在正常/盐胁迫条件下用作生物肥料。在这项研究中，根据对 Debhata 和 Satkhira 地区的 20 个根瘤菌分离株的较高耐盐性，从总共 8 个耐盐细菌分离株中选择了 8 个耐盐细菌分离株。耐盐细菌分离株的 16S rRNA 基因测序结果表明，它们属于 Halobacillus、Bacillus、Acinetobactor 和 Enterobactor 属。总共使用了 10 种耐盐根瘤菌（其他 2 种细菌已被分离并已报道对水稻生长有益）作为单一接种剂和组合接种剂，并应用于盆栽水稻。为了研究它们提高水稻生长的能力，在不存在或存在（浓度为 40 或 80 mmol/L）NaCl 的情况下以及不存在或存在根瘤菌的情况下，测量了幼苗期的茎和根长和重量、叶绿素含量以及生殖期的存活率和产量等生理参数。在生殖期，在 80 mmol/L NaCl 中，未接种的植物有 50%没有结任何种子，而接种了根瘤菌组合的水稻植物则 100%存活。与单一物种的应用相比，在应用的最大 NaCl 浓度下，耐盐根瘤菌组合的接种显示出显著更高的叶绿素保留率和产量。因此，在中度盐度下，使用耐盐根瘤菌组合作为水稻植物的生物接种剂可以协同缓解胁迫的影响，促进水稻的生长和产量。
