Characterization of plant growth-promoting endophytic fungi from Aegle marmelos Corr. and their role in growth enhancement and yield in rice

Plant growth-promoting endophytes (PGPE) are microorganisms which reside in plant tissues and are beneficial to the host in plant growth promotion and pathogen resistance. They are the eco-friendly and sustainable alternative to chemical fertilizers and pesticides. This study aimed to analyze the plant growth-promoting properties of the five endophytic fungal strains from the medicinal plant Aegle marmelos Corr. and evaluate their effects on Oryza sativa plants. Firstly, endophytes were isolated from the different parts of A. marmelos and identified by ITS sequencing. Phosphate solubilization ability was checked in Pikovskaya's agar medium, IAA secretion was measured by the Salkowski colourimetric method, and ACC deaminase activity was checked by Penrose's method. Four endophytic fungal strains with promising PGP activities were inoculated into rice seeds to check their growth promotion in rice. The strain Purpureocillium lilacinum (AMR2) enhanced the seed vigour of rice seeds and demonstrated excellent root colonization ability. Periconia byssoides (AML2) and Medicopsis romeroi (AMS3) were the most effective plant growth-promoting agents, leading to both crop yield improvement and enhanced plant morphological growth due to their great ability to solubilize inorganic phosphate, ACC deaminase activity and production of IAA and Gibberellin A3 (GA3). These endophytic strains could serve as microbial inoculants to enhance crop production, offering an eco-friendly alternative.