AlHosani Mohamed, Kappachery Sajeesh, Khan Tanveer Alam, Karumannil Sameera, Mundra Sunil, Gururani Mayank Anand
Biology Department, College of Science, United Arab Emirates University, P.O. Box 15551, Al-Ain, United Arab Emirates.
Biology Department, College of Science, United Arab Emirates University, P.O. Box 15551, Al-Ain, United Arab Emirates; Khalifa Center for Genetic Engineering and Biotechnology, United Arab Emirates University, P.O. Box 15551, Al-Ain, United Arab Emirates.
Plant Sci. 2025 Jul 2:112642. doi: 10.1016/j.plantsci.2025.112642.
Plant growth-promoting rhizobacteria (PGPRs) can effectively alleviate the adverse effects of salt stress on plants. This study isolated PGPRs from a high-saline mangrove ecosystem in Abu Dhabi, focusing on strains with ACC deaminase (ACCD) activity to reduce stress-induced ethylene and other plant growth-promoting (PGP) traits, such as phosphate solubilization (P+). A total of 57 salt-tolerant bacterial isolates from the mangrove rhizosphere were initially screened for ACCD and P+ activities. Of these, 24 isolates exhibited positive PGP traits and were further assessed for their ability to enhance salt stress tolerance in tomato seedlings. Nine selected isolates significantly improved seedling growth compared to uninoculated controls on agar plates with 75mM NaCl. Following further screening, four isolates (B1-B4) were chosen for greenhouse trials. Under greenhouse conditions, Bacillus subtilis (B1) and Bacillus siamensis (B3) markedly mitigated salt stress effects and enhanced tomato plant tolerance, while Bacillus velezensis (B2) showed moderate benefits, and Priestia filamentosa (B4) had the least impact. Inoculation with B1 and B3 significantly increased shoot length, shoot fresh and dry weights, root fresh and dry weights, and flower count under saline conditions. Chlorophyll-a fluorescence analysis indicated the highest photosystem II (PSII) efficiency in B1- and B3-treated plants, moderate efficiency in B2-treated plants, and the lowest in B4-treated and uninoculated controls. The leaf spectral reflectance indices of tomato plants inoculated with B1 and B3 were the highest, followed by moderate increases in B2-treated plants, while the lowest values were observed in plants treated with B4 and the uninoculated controls. Variations in salt tolerance among tomato plants inoculated with B1-B4 correlated with the isolates' PGP traits, especially ACCD activity and IAA production. Overall, B1 and B3 show strong potential as biofertilizers to enhance tomato production under saline conditions.
植物促生根际细菌（PGPRs）能有效缓解盐胁迫对植物的不利影响。本研究从阿布扎比的一个高盐红树林生态系统中分离出PGPRs，重点关注具有ACC脱氨酶（ACCD）活性的菌株，以降低胁迫诱导的乙烯以及其他植物促生（PGP）特性，如磷溶解（P+）。最初从红树林根际筛选了57株耐盐细菌分离株，检测其ACCD和P+活性。其中，24株分离株表现出阳性PGP特性，并进一步评估它们提高番茄幼苗耐盐性的能力。与在含有75mM NaCl的琼脂平板上未接种的对照相比，9株选定的分离株显著促进了幼苗生长。进一步筛选后，选择了4株分离株（B1 - B4）进行温室试验。在温室条件下，枯草芽孢杆菌（B1）和暹罗芽孢杆菌（B3）显著减轻了盐胁迫影响，增强了番茄植株的耐受性，而贝莱斯芽孢杆菌（B2）表现出中等效果，丝状Priestia（B4）的影响最小。在盐胁迫条件下，接种B1和B3显著增加了茎长、茎鲜重和干重、根鲜重和干重以及花数。叶绿素a荧光分析表明，B1和B3处理的植株中光系统II（PSII）效率最高，B2处理的植株效率中等，B4处理和未接种的对照效率最低。接种B1和B3的番茄植株的叶片光谱反射指数最高，其次是B2处理的植株有中等程度增加，而B4处理的植株和未接种的对照中观察到最低值。接种B1 - B4的番茄植株耐盐性的差异与分离株的PGP特性相关，尤其是ACCD活性和吲哚乙酸（IAA）的产生。总体而言，B1和B3作为生物肥料在盐胁迫条件下提高番茄产量具有很大潜力。
