Laboratoire de Biologie des Systèmes Microbiens, Ecole Normale Supérieure de Kouba, Algiers, Algeria.
Département des Sciences Naturelles, École Normale Supérieure de Laghouat, BP 4033, 03000, Laghouat, Algeria.
World J Microbiol Biotechnol. 2021 Dec 13;38(1):16. doi: 10.1007/s11274-021-03203-2.
The use of halotolerant beneficial plant-growth-promoting (PGP) bacteria is considered as a promising eco-friendly approach to improve the salt tolerance of cash crops. One strategy to enhance the possibility of obtaining stress-alleviating bacteria is to screen salt impacted soils. In this study, amongst the 40 endophytic bacteria isolated from the roots of Sahara-inhabiting halophytes Atriplex halimus L. and Lygeum spartum L., 8 showed interesting NaCl tolerance in vitro. Their evaluation, through different tomato plant trials, permitted the isolate IS26 to be distinguished as the most effective seed inoculum for both plant growth promotion and mitigation of salt stress. On the basis of 16S rRNA gene sequence, the isolate was closely related to Stenotrophomonas rhizophila. It was then screened in vitro for multiple PGP traits and the strain-complete genome was sequenced and analysed to further decipher the genomic basis of the putative mechanisms underlying its osmoprotective and plant growth abilities. A remarkable number of genes putatively involved in mechanisms responsible for rhizosphere colonization, plant association, strong competition for nutrients, and the production of important plant growth regulator compounds, such as AIA and spermidine, were highlighted, as were substances protecting against stress, including different osmolytes like trehalose, glucosylglycerol, proline, and glycine betaine. By having genes related to complementary mechanisms of osmosensing, osmoregulation and osmoprotection, the strain confirmed its great capacity to adapt to highly saline environments. Moreover, the presence of various genes potentially related to multiple enzymatic antioxidant processes, able to reduce salt-induced overproduction of ROS, was also detected.
利用耐盐有益植物促生（PGP）细菌被认为是一种有前途的环保方法，可以提高经济作物的耐盐性。增强获得缓解压力细菌可能性的一种策略是筛选受盐影响的土壤。在这项研究中，从撒哈拉地区耐盐植物 Atriplex halimus L. 和 Lygeum spartum L. 的根部分离的 40 种内生细菌中，有 8 种在体外表现出对 NaCl 的有趣耐受性。通过不同的番茄植物试验对它们进行评估，结果表明分离株 IS26 是最有效的种子接种体，可促进植物生长并缓解盐胁迫。基于 16S rRNA 基因序列，该分离株与 Stenotrophomonas rhizophila 密切相关。然后在体外筛选其具有多种 PGP 特性，并对该菌株的全基因组进行测序和分析，以进一步解析其在耐盐性和植物生长能力方面的潜在机制的基因组基础。大量推测与根际定殖、植物共生、对营养物质的强烈竞争以及产生重要植物生长调节剂化合物（如 AIA 和亚精胺）等机制相关的基因被突出强调，同时还强调了一些抗应激物质，包括不同的渗透物，如海藻糖、葡糖基甘油、脯氨酸和甘氨酸甜菜碱。该菌株具有与渗透压感应、渗透压调节和渗透压保护相关的互补机制的基因，证实了其适应高盐环境的巨大能力。此外，还检测到各种可能与多种酶抗氧化过程相关的基因，这些基因能够减少盐诱导的 ROS 过度产生。
