Salinity Influences Endophytic Bacterial Communities in Rice Roots from the Indian Sundarban Area

In "Sundarbans", the coastal regions of the West Bengal, soil salinity has always been one of the major causes of reduction in yield in these regions. The use of endophytic is a well-demanded strategy to mitigate the problems of salt stress and rice productivity. The present study attempted to analyze rice root endogenous microbial diversity and their relationship with soil salinity and physicochemical factors in the salt stressed region of Sundarbans, India using amplicon metagenomics approaches. Our investigation indicates, that the unique microbiome slightly acidic nutrient enriched non-saline zone is characterized by microbial genera that reported either having plant growth promotion (Flavobacterium, Novosphingobium, and Kocuria) or biocontrol abilities (Leptotrichia), whereas high ionic alkaline saline stressed zone dominated with either salt-tolerant microbes or less characterized endophytes (Arcobacter and Vogesella). The number of genera represented by significantly abundant OTUs was higher in the non-saline zone compared to that of the saline stressed zone probably due to higher nutrient concentrations and the absence of abiotic stress factors including salinity. Physicochemical parameters like nitrogen, phosphorus, and potassium were found significantly positively correlated with Muribaculaceae highly enriched in the non-saline zone. However, relative dissolved oxygen was found significantly negatively correlated with Rikenellaceae and Desulfovibrionaceae, enriched in the non-saline soil. This study first provides the detailed characterizations of rice root endophytic bacterial communities as well as their diversity contributed by measured environmental parameters in salinity Sundarbans areas. Since this study deals with two gradients of salinity, connecting the microbial diversity with the salinity range could be targeted for the use as "bioindicator" taxa and bio-fertilizer formulation in salt-affected regions.