Exploring Stress-Tolerant Endophytes From Leucas Aspera Root For Climate-Resilient Agriculture

Abstract

In agriculture, endophytic bacteria are becoming more environmentally friendly than chemical inputs because of their capacity to increase plant development and resilience to stress. Thirty bacterial isolates were isolated from Leucas aspera roots for the present study.  After a preliminary screening for plant growth-promoting (PGP) characteristics, four isolates with robust activity were chosen. Following biochemical characterisation, these isolates were assessed for their ability to withstand biotic (antagonism against phytopathogens) and abiotic (temperature, salinity and drought) stress. Followingly, the impact of the chosen isolates on tomato seed germination and seedling development was evaluated. Two isolates out of the four showed notable growth-promoting activity: LAR04 was more successful in root formation and LAR25 consistently increased shoot biomass indicating isolate-specific advantages. LAR25 was identified as Bacillus pumilus by molecular identification using 16S rRNA gene sequencing. Along with resilience to abiotic stresses and antifungal activity against phytopathogens, both isolates exhibited a variety of PGP characteristics such as phosphate solubilization, indole-3-acetic acid synthesis, urease activity and oxidase activity. On comparison to uninoculated controls, inoculating tomato seedlings with these isolates greatly increased biomass accumulation, root and shoot length and general vigor. The work highlights the potential of endophytes derived from Leucas aspera as viable bioinoculants for sustainable tomato production and offers a basis for creating environmentally friendly microbial formulations to improve crop resilience and productivity.