Genome-wide investigation of GRAM-domain containing genes in rice reveals their role in plant-rhizobacteria interactions and abiotic stress responses.

A comprehensive genome-wide survey of GRAM-domain containing genes in rice identified total 64 genes which were grouped into six classes and were physically mapped onto different rice chromosomes. GRAM domain-containing genes showed total 8 segmental and 3 tandem duplications. Comparative physical mapping between rice OsGRAM and its orthologs in related C4-crops depicted evolutionary insights into this gene family. Expression analyses of OsGRAM genes in rice roots subjected to salt stress with or without Bacillus amyloliquefaciens (SN13) inoculation revealed significant differential expression patterns suggesting their crucial role in beneficial plant-rhizobacteria interactions under stress. Further, expression analyses of selected 15 candidate genes with ≥3.0-fold induction in salt + SN13 treated samples indicated their precise and overlapping expression patterns under various abiotic stresses and phytohormones at early (1 h) and late (24 h) durations which might be ultimately responsible for functional divergence and beneficial plant-microbe interactions. Furthermore, OsGRAM27 and OsGRAM47 could be considered as potential candidate genes for further functional characterization and application in crop improvement since these genes showed positive modulation in stress under the influence of SN13. This study provides new dimensions into the evolution and divergence of OsGRAM and their role in plant-rhizobacteria interactions that could be utilized for improving stress tolerance in crops.