Chaudhary Twinkle, Gera Rajesh, Shukla Pratyoosh
Enzyme Technology and Protein Bioinformatics Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, India.
Department of Microbiology, Chaudhary Charan Singh Haryana Agricultural University, Hisar, India.
Front Bioeng Biotechnol. 2021 Jan 18;8:617034. doi: 10.3389/fbioe.2020.617034. eCollection 2020.
Plant growth-promoting rhizobacteria (PGPR) are root endophytic bacteria used for growth promotion, and they have broader applications in enhancing specific crop yield as a whole. In the present study, we have explored the potential of MB-17a as an endophytic bacterium isolated from the roots of the mung bean () plant. Furthermore, this bacterium was sequenced and assembled to reveal its genomic potential associated with plant growth-promoting traits. Interestingly, the root endophyte MB-17a showed all essential PGPR traits which were determined by biochemical and PGPR tests. It was noted that this root endophytic bacterium significantly produced siderophores, indole acetic acid (IAA), ammonia, and ACC deaminase and efficiently solubilized phosphate. The maximum IAA and ammonia produced were observed to be 110.5 and 81 μg/ml, respectively. Moreover, the PGPR potential of this endophytic bacterium was also confirmed by a pot experiment for mung bean (), whose results show a substantial increase in the plant's fresh weight by 76.1% and dry weight by 76.5% on the 60th day after inoculation of MB-17a. Also, there is a significant enhancement in the nodule number by 66.1% and nodule fresh weight by 162% at 45th day after inoculation with 100% field capacity after the inoculation of MB-17a. Besides this, the functional genomic annotation of MB-17a determined the presence of different proteins and transporters that are responsible for its stress tolerance and its plant growth-promoting properties. It was concluded that the unique presence of genes like , and enhances the symbiosis process during adverse conditions in this endophyte. Through Rapid Annotation using Subsystem Technology (RAST) analysis, the key genes involved in the production of siderophores, volatile compounds, indoles, nitrogenases, and amino acids were also predicted. In conclusion, the strain described in this study gives a novel idea of using such type of endophytes for improving plant growth-promoting traits under different stress conditions for sustainable agriculture.
植物促生根际细菌（PGPR）是用于促进生长的根内生细菌，它们在提高特定作物整体产量方面具有更广泛的应用。在本研究中，我们探索了从绿豆（）植物根部分离出的内生细菌MB - 17a的潜力。此外，对该细菌进行了测序和组装，以揭示其与植物促生长特性相关的基因组潜力。有趣的是，根内生菌MB - 17a表现出通过生化和PGPR测试确定的所有基本PGPR特性。值得注意的是，这种根内生细菌显著产生铁载体、吲哚乙酸（IAA）、氨和ACC脱氨酶，并能有效地溶解磷酸盐。观察到产生的最大IAA和氨分别为110.5和81μg/ml。此外，通过绿豆（）盆栽试验也证实了这种内生细菌的PGPR潜力，其结果表明，在接种MB - 17a后第60天，植株鲜重显著增加76.1%，干重增加76.5%。同样，在接种MB - 17a且土壤含水量为100%田间持水量的情况下，接种后第45天，根瘤数量显著增加66.1%，根瘤鲜重增加162%。除此之外，MB - 17a的功能基因组注释确定了负责其胁迫耐受性和植物促生长特性的不同蛋白质和转运蛋白的存在。得出的结论是，诸如、和等基因的独特存在增强了这种内生菌在不利条件下的共生过程。通过使用子系统技术（RAST）分析进行快速注释，还预测了参与铁载体、挥发性化合物、吲哚、固氮酶和氨基酸产生的关键基因。总之，本研究中描述的菌株为在不同胁迫条件下利用此类内生菌改善植物促生长特性以实现可持续农业提供了新思路。
