Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi, Uttar Pradesh, 221005, India; Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, 276957612, USA.
National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India.
Plant Physiol Biochem. 2024 Jul;212:108731. doi: 10.1016/j.plaphy.2024.108731. Epub 2024 May 15.
Seed endophytic bacteria have been shown to promote the growth and development of numerous plants. However, the underlying mechanism still needs to be better understood. The present study aims to investigate the role of a seed endophytic bacterium Lysinibacillus sp. (ZM1) in promoting plant growth and shaping the root architecture of maize seedlings. The study explores how bacteria-mediated auxin biosynthesis and nitrogen metabolism affect plant growth promotion and shape the root architecture of maize seedlings. The results demonstrate that ZM1 inoculation significantly enhances root length, root biomass, and the number of seminal roots in maize seedlings. Additionally, the treated seedlings exhibit increased shoot biomass and higher levels of photosynthetic pigments. Confocal laser scanning microscopy (CLSM) analysis revealed extensive colonization of ZM1 on root hairs, as well as in the cortical and stellar regions of the root. Furthermore, LC-MS analysis demonstrated elevated auxin content in the roots of the ZM1 treated maize seedlings compared to the uninoculated control. Inoculation with ZM1 significantly increased the levels of endogenous ammonium content, GS, and GOGAT enzyme activities in the roots of treated maize seedlings compared to the control, indicating enhanced nitrogen metabolism. Furthermore, inoculation of bacteria under nitrogen-deficient conditions enhanced plant growth, as evidenced by increased root shoot length, fresh and dry weights, average number of seminal roots, and content of photosynthetic pigments. Transcript analysis indicated upregulation of auxin biosynthetic genes, along with genes involved in nitrogen metabolism at different time points in roots of ZM1-treated maize seedlings. Collectively, our findings highlight the positive impact of Lysinibacillus sp. ZM1 inoculation on maize seeds by improving root architecture through modulation of auxin biosynthesis and affecting various nitrogen metabolism related parameters. These findings provide valuable insights into the potential utilization of seed endophytic bacteria as biofertilizers to enhance plant growth and yield in nutrient deficient soils.
种子内生细菌已被证明能促进许多植物的生长和发育。然而，其潜在的机制仍需要更好地理解。本研究旨在探讨种子内生细菌Lysinibacillus sp.（ZM1）在促进植物生长和塑造玉米幼苗根系结构中的作用。本研究探讨了细菌介导的生长素生物合成和氮代谢如何影响植物生长促进和塑造玉米幼苗的根系结构。结果表明，ZM1 接种显著增强了玉米幼苗的根长、根生物量和初生根数量。此外，处理后的幼苗表现出增加的地上生物量和更高水平的光合色素。共聚焦激光扫描显微镜（CLSM）分析显示，ZM1 广泛定植于根毛上，以及根的皮层和星状区域。此外，LC-MS 分析表明，ZM1 处理的玉米幼苗根中的生长素含量高于未接种对照。与未接种对照相比，ZM1 接种显著增加了处理的玉米幼苗根中内源性铵含量、GS 和 GOGAT 酶活性，表明氮代谢增强。此外，在氮缺乏条件下接种细菌增强了植物的生长，表现为根-茎长度、鲜重和干重、初生根平均数量以及光合色素含量的增加。转录分析表明，ZM1 处理的玉米幼苗根中生长素生物合成基因以及参与氮代谢的基因在不同时间点均上调。综上所述，我们的研究结果强调了 Lysinibacillus sp. ZM1 接种对玉米种子的积极影响，通过调节生长素生物合成和影响各种氮代谢相关参数来改善根系结构。这些发现为利用种子内生细菌作为生物肥料在养分缺乏的土壤中增强植物生长和产量提供了有价值的见解。
