Mathew Betty T, Torky Yaser, Amin Amr, Mourad Abdel-Hamid I, Ayyash Mutamed M, El-Keblawy Ali, Hilal-Alnaqbi Ali, AbuQamar Synan F, El-Tarabily Khaled A
Department of Biology, College of Science, United Arab Emirates University, Al-Ain, United Arab Emirates.
Department of Mechanical Engineering, College of Engineering, United Arab Emirates University, Al-Ain, United Arab Emirates.
Front Microbiol. 2020 Apr 3;11:552. doi: 10.3389/fmicb.2020.00552. eCollection 2020.
is a promising halophytic cash crop that grows in seawater of the intertidal zone of the west-north coast of the UAE. This study assess plant growth promoting (PGP) capabilities of halotolerant actinobacteria isolated from rhizosphere of to be used as biological inoculants on seawater-irrigated plants. Under laboratory conditions, a total of 39 actinobacterial strains were isolated, of which 22 were tolerant to high salinity (up to 8% w/v NaCl). These strains were further screened for their abilities to colonize roots ; the most promising ones that produced indole-3-acetic acid, polyamines (PA) or 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase (ACCD) were selected for rhizosphere-competency under naturally competitive environment. Three outstanding rhizosphere-competent isolates, (), (), and () producing auxins, PA and ACCD, respectively, were investigated individually and as consortium (//) to determine their effects on the performance of in the greenhouse. Individual applications of strains on seawater-irrigated plants significantly enhanced shoot and root dry biomass by 32.3-56.5% and 42.3-71.9%, respectively, in comparison to non-inoculated plants (control). In addition, plants individually treated with , and resulted in 46.1, 60.0, and 69.1% increase in seed yield, respectively, when compared to control plants. Thus, the synergetic combination of strains had greater effects on biomass (62.2 and 77.9% increase in shoot and root dry biomass, respectively) and seed yield (79.7% increase), compared to the control treatment. Our results also showed significant ( < 0.05) increases in the levels of photosynthetic pigments, endogenous auxins and PA, but a reduction in the levels of ACC in tissues of plants inoculated with //. We conclude that the consortium of isolates was the most effective treatment on growth; thus confirmed by principal component and correlation analyses. To this best of our knowledge, this is the first report about halotolerant rhizosphere-competent PGP actinobacteria thriving in saline soils that can potentially contribute to promoting growth and increasing yield of . These halotolerant actinobacterial strains could potentially be exploited as biofertilizers to sustain crop production in arid coastal areas.
是一种很有前景的盐生经济作物，生长在阿联酋西北海岸潮间带的海水中。本研究评估了从的根际分离出的耐盐放线菌的植物生长促进（PGP）能力，以用作海水灌溉植物的生物接种剂。在实验室条件下，共分离出39株放线菌菌株，其中22株耐受高盐度（高达8% w/v NaCl）。进一步筛选这些菌株在根上定殖的能力；选择最有前景的能产生吲哚-3-乙酸、多胺（PA）或1-氨基环丙烷-1-羧酸（ACC）脱氨酶（ACCD）的菌株，在自然竞争环境下进行根际适应性研究。分别对三株出色的具有根际适应性的分离株（）、（）和（）进行研究，它们分别产生生长素、PA和ACCD，并作为联合体（//）进行研究，以确定它们对温室中生长性能的影响。与未接种的植物（对照）相比，将菌株单独应用于海水灌溉植物显著提高了地上部和根部的干生物量，分别提高了32.3 - 56.5%和42.3 - 71.9%。此外，与对照植物相比，分别用、和单独处理的植物种子产量分别提高了46.1%、60.0%和69.1%。因此，与对照处理相比，菌株的协同组合对生物量（地上部和根部干生物量分别增加62.2%和77.9%）和种子产量（增加79.7%）有更大的影响。我们的结果还表明，接种//的植物组织中光合色素、内源生长素和PA的水平显著（< 0.05）增加，但ACC水平降低。我们得出结论，分离株联合体对生长的处理最有效；主成分分析和相关性分析证实了这一点。据我们所知，这是关于在盐渍土壤中茁壮成长的耐盐根际适应性PGP放线菌的首次报道，这些放线菌可能有助于促进生长和提高产量。这些耐盐放线菌菌株有可能被开发为生物肥料，以维持干旱沿海地区的作物生产。
