Division of Crop Production and Protection, Central Institute of Medicinal and Aromatic Plants, Lucknow 226015, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India.
Division of Crop Production and Protection, Central Institute of Medicinal and Aromatic Plants, Lucknow 226015, India.
Microbiol Res. 2024 Jun;283:127673. doi: 10.1016/j.micres.2024.127673. Epub 2024 Mar 7.
The rich diversity of microbial endophytic communities associated with plants, often referred to as the second genome, serves as a compelling illustration of efficient co-evolution. This noteworthy partnership plays a pivotal role in sustaining plant well-being and enhancing plant adaptability across diverse habitats. Therefore, examining the diversity of endophytic microbes associated with their particular host plant is valuable for gaining insights into the vast spectrum of plant-microbe interactions. The present experiments aimed at investigating the bacterial endophytic diversity in both root and shoot tissues of Pelargonium graveolens, employing culture dependent and culture independent high-throughput metagenomics approach. A total of 614 and 620 operational taxonomic units (OTUs), encompassing 291 and 229 genera, were identified in the shoot and root tissues of P. graveolens, respectively. Furthermore, the subsequent classification of OTUs revealed 15 highly abundant phyla, with Proteobacteria dominating both root and shoot tissues. Notably, an exceptionally high abundance of Firmicutes phyla was observed in the shoot compared to the root. Additionally, 30 bacterial endophytes from the root, stem, petiole, and leaves were isolated and molecularly characterized, unveiling a consistent pattern of diversity distribution between the root and shoot of P. graveolens. Upon screening all isolates for plant growth promoting traits, Pseudomonas oryzihabitans was found to be positive for major biochemical test like nitrogen fixation, phosphate solubilization etc. and on inoculation resulted in about two-fold increase in content of essential oil accompanied by a significant rise in the geraniol and citronellol content. Diving deep into the genetic constitution of P. oryzihabitans unveiled a substantial number of genes directly and indirectly contributing to the endophyte's capability in colonizing host plants effectively. In summary, data obtained from metagenomics and culture dependent approaches including glass house trials suggest potential bacterial endophytes suitable for field applications for yield enhancement and in planta secondary metabolite enhancement investigations.
植物内生微生物群落的丰富多样性，通常被称为“第二基因组”，生动地展示了高效的共同进化。这种显著的伙伴关系在维持植物健康和增强植物在各种生境中的适应能力方面发挥着关键作用。因此，研究与特定宿主植物相关的内生微生物的多样性，对于深入了解植物-微生物相互作用的广阔范围具有重要意义。本实验旨在采用依赖培养和独立于培养的高通量宏基因组学方法，研究 Pelargonium graveolens 根和茎组织中的细菌内生微生物多样性。在 P. graveolens 的茎和根组织中分别鉴定出 614 个和 620 个操作分类单元 (OTU)，包含 291 个和 229 个属。此外，OTU 的后续分类揭示了 15 个高度丰富的门，其中根和茎组织中均以 Proteobacteria 为主。值得注意的是，与根组织相比，茎组织中 Firmicutes 门的丰度异常高。此外，从根、茎、叶柄和叶片中分离出 30 种细菌内生菌，并进行了分子鉴定，揭示了 P. graveolens 根和茎之间多样性分布的一致模式。在对所有分离株进行植物生长促进特性筛选后，发现 Pseudomonas oryzihabitans 在氮固定、磷酸盐溶解等主要生化测试中呈阳性，接种后，精油含量增加了近两倍，同时香叶醇和香茅醇含量显著增加。深入研究 P. oryzihabitans 的遗传组成揭示了大量直接和间接有助于内生菌有效定殖宿主植物的基因。总之，宏基因组学和依赖培养的方法（包括温室试验）获得的数据表明，一些内生细菌具有适合田间应用的潜力，可用于提高产量和增强植物体内次生代谢物的研究。
