Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India.
Natural Product Biotechnology Group, Agricultural and Food Engineering Department, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India.
Microbiol Res. 2020 Dec;241:126582. doi: 10.1016/j.micres.2020.126582. Epub 2020 Aug 19.
Exploring the beneficial interactions between plant and endophytes could be an effective strategy in the implementation of sustainable agricultural practices to enhance crop productivity. In this study, we aimed to evaluate holistically the plant growth promoting (PGP) abilities rendered by seed-transmitted endophytic bacteria isolated from in vitro grown calli of two rice cultivars. Nine bacterial endophytes, designated as PB001-PB009, were isolated and identified at the genus level through 16S rRNA gene sequence analysis. Biochemical investigations disclosed that they possess several PGP traits, such as phosphate solubilization, indole acetic acid biosynthesis, ammonia production, nitrogen fixation, amylase production and siderophore production. Results in gnotobiotic conditions revealed an increase in fresh weight, dry weight, root length and shoot length of seedlings germinated from endophyte-primed seeds than the control (uninoculated) set in a non-host and two host rice cultivars. In net house experiments, plants germinated from Micrococcus sp. PB001, Pseudomonas sp. PB002, Methylobacterium sp. PB005 and Methylorubrum sp. PB009 primed seeds showed an increase of upto 34.06 %, 38.77 %, 182.87 %, 16.59 % and 33.52 % in chlorophyll content, number of tillers/plant, number of grains/plant, grain size and grain weight, respectively than control plant sets in the non-host rice cultivar, further validating inter-cultivar PGP abilities of these endophytes. Metabolite profiling unfolded the abundance of few metabolites that are involved in pathways associated with PGP traits, in seedlings germinated from the endophyte-primed seeds. Together, the study documents the effect of seed-transmitted endophytic bacteria on intra- and inter-cultivar PGP by modulating certain sets of metabolites in rice plant, and is promising in developing bioinoculant formulations employing these selected endophytes for enhancement of rice productivity.
探索植物和内生菌之间的有益相互作用可能是实施可持续农业实践以提高作物生产力的有效策略。在这项研究中，我们旨在全面评估从两种水稻品种的离体愈伤组织中分离的种传内生细菌的植物生长促进（PGP）能力。通过 16S rRNA 基因序列分析，将 9 种内生细菌鉴定为 PB001-PB009，并在属水平上进行了鉴定。生化研究表明，它们具有多种 PGP 特性，如溶磷、吲哚乙酸合成、氨产生、固氮、淀粉酶生产和铁载体生产。在无菌条件下的结果表明，与对照（未接种）相比，从内生菌接种的种子中萌发的幼苗的鲜重、干重、根长和苗长均有所增加，在非宿主和两种宿主水稻品种中均如此。在网室实验中，从 Micrococcus sp. PB001、Pseudomonas sp. PB002、Methylobacterium sp. PB005 和 Methylorubrum sp. PB009 接种种子中萌发的植物，在非宿主水稻品种中，叶绿素含量、每株分蘖数、每株粒数、粒大小和粒重分别增加了 34.06%、38.77%、182.87%、16.59%和 33.52%，进一步验证了这些内生菌的种间 PGP 能力。代谢物分析揭示了从内生菌接种的种子中萌发的幼苗中参与 PGP 特性相关途径的少数代谢物的丰度。总的来说，该研究记录了种传内生细菌通过调节水稻植物中某些代谢物来影响种内和种间 PGP 的作用，并且有望开发使用这些选定内生菌的生物接种剂制剂来提高水稻生产力。
