Inter-Genera Colonization of Endophytes in Tomato and Their Complementary Effects on Na/K Balance, Oxidative Stress Regulation, and Root Architecture Under Elevated Soil Salinity.

Endophytic bacilli of ethano-botanical plant were screened for salt stress-alleviating traits in tomato. Four promising endophytes ( BTL5, GTR8, GTR11, and GTS16) were used in this study. Confocal scanning laser microscopic studies revealed the inter-genera colonization of endophytes in tomato plants, giving insights for widening the applicability of potential endophytes to other crops. Furthermore, in a pot trial under 150 mM NaCl concentration, the inoculated endophytes contributed in reducing salt toxicity and improving recovery from salt-induced oxidative stress by different mechanisms. Reduction in reactive oxygen species (ROS) (sub-cellular HO and superoxide) accumulation was observed besides lowering programmed cell death and increasing chlorophyll content. Endophyte inoculation supplemented the plant antioxidant enzyme system the modulation of enzymatic antioxidants, , peroxidase, ascorbate peroxidase, superoxide dismutase, and catalase, apart from increasing proline and total phenolics. Antioxidants like proline have dual roles of antioxidants and osmoregulation, which might also have contributed to improved water relation under elevated salinity. Root architecture, ., root length, projection area, surface area, average diameter, tips, forks, crossings, and the number of links, was improved upon inoculation, indicating healthy root growth and enhanced nutrient flow and water homeostasis. Regulation of Na/K balance and water homeostasis in the plants were also evident from the modulation in the expression of abiotic stress-responsive genes, ., 1, 1, 1, 2, 16, and 39. Shoot tissues staining with light-excitable Na indicator Sodium Green Tetra (tetramethylammonium) salt showed low sodium transport and accumulation in endophyte-inoculated plants. All four endophytes exhibited different mechanisms for stress alleviation and indicated complementary effects on plant growth. Furthermore, this could be harnessed in the form of a consortium for salt stress alleviation. The present study established inter-genera colonization of endophytes in tomato and revealed its potential in maintaining Na/K balance, reducing ROS, and improving root architecture under elevated salinity.