Pseudomonas mosselii improves cold tolerance of Asian rice (Oryza sativa L.) in a genotype-dependent manner by increasing proline in japonica and reduced glutathione in indica varieties.

Cold stress is an important factor limiting rice production and distribution. Identifying factors that contribute to cold tolerance in rice is of primary importance. While some plant specific genetic factors involved in cold tolerance have been identified, the role of the rice microbiome remains unexplored. In this study, we evaluated the influence of plant growth promoting bacteria (PGPB) with the ability of phosphate solubilization on rice cold tolerance and survival. To reach this goal, inoculated and uninoculated 2-week-old seedlings were cold stressed and evaluated for survival and other phenotypes such as electrolyte leakage (EL) and necessary elements for cold tolerance. The results of this study showed that of the five bacteria, Pseudomonas mosselii, improved both indica and japonica varietal plants' survival and decreased EL, indicating increased membrane integrity. We observed different possible cold tolerance mechanisms in japonica and indica plants such as increases in proline and reduced glutathione levels, respectively. This bacterium also improved the shoot growth of cold exposed indica plants during the recovery period. This study confirmed the host genotype dependent activity of P. mosselii and indicated that there is an interaction between specific plant genes and bacterial genes that causes different plant responses to cold stress.