Wheat Growth Dependent Succession of Culturable Endophytic Bacteria and Their Plant Growth Promoting Traits

Endophytic bacteria present ubiquitously in all plant parts. Their community structure may vary depending on plant tissue and growth condition. This work mainly focused on exploring the diversity of culturable nitrogen-fixing endophytic bacteria in above-ground plant parts of wheat by harvesting it during various growth points (Seed stage, 1st, 2nd, and 3rd month old plants, respectively). Distinct endophytic bacterial colonies were selected on Jensen's agar plate. Based on the 16S rRNA sequencing, 43 putative nitrogen-fixing endophytic bacteria were identified. Most of the isolates were found unique to the plant growth phase except for Pseudomonas sp., Bacillus sp., Paenibacillus sp., Microbacterium sp., Exiguobacterium sp. Further, endophytic bacteria were scrutinized for their plant growth promoting traits. They were found positive for IAA production (100%), P-solubilization (21%), Zn-solubilization (63%), ammonia production (93%), and nifH gene (33%). Extracellular enzyme production was found positive for cellulase (98%), pectinase (98%), and protease (100%). Their endophytic colonization ability was assessed using reactive oxygen species (ROS) induction assay, upon their entry inside the host plant.