Diversity of halotolerant endophytes from wheat ( Triticum aestivum ) and their response to mitigate salt stress in plants

Soil salinity is one of the major limiting factors that decline crop production. About 20% of irrigated land soil is presently affected by high salinity worldwide reducing the crop yield by 20–50%. Endophytes play an important role in coping with the salinity stress in plants. In present study, 224 bacterial endophytes exhibiting discrete salt tolerance ranging from 0.5 M to 4.0 M were isolated from the shoot and root of wheat. Endophytic isolates showed varying salt tolerance potential and only a few (7.14%) possess the capability to tolerate high salt concentration (≥3.0 M NaCl). The 16S rRNA gene sequence exhibited 65 discrete OTUs recovered from the root (53.85%) and shoot tissue (46.15%) of the wheat plant. The 16S rRNA gene sequencing revealed the majority of phylum were Firmicutes (81.54%), Proteobacteria (13.85%), and Actinobacteria (4.62%) and dominated by Bacillus (63.08%), Priestia (13.85%), Pseudomonas (10.77%), Exiguobacterium and Curtobacterium (3.08% each). Moreover, this study is the first report for the abundance of certain bacterial species as endophytes from wheat cultivated under saline-affected regions like Bacillus australimaris, B. vallismortis, B. haynesii, Rossellomorea marisflavi, Exiguobacterium undae, Curtobacterium pusillum. The selected endophytes significantly reduced the detrimental influence of salt stress and enhanced various growth parameters like root length, shoot length, fresh weight, and dry weight of salt susceptible wheat variety ‘HD 2733’ as compared to the control. The present study might be beneficial to restore soil fertility and reduce the loss of crop productivity under saline stress conditions.