Microbe‐induced drought tolerance by ABA‐mediated root architecture and epigenetic reprogramming

The use of beneficial microbes to mitigate drought stress tolerance of plants is of great potential albeit little understood. We show here that a root endophytic desert bacterium, Pseudomonas argentinensis strain SA190, enhances drought stress tolerance in Arabidopsis . Transcriptome and genetic analysis demonstrate that SA190‐induced root morphogenesis and gene expression is mediated via the plant abscisic acid (ABA) pathway. Moreover, we demonstrate that SA190 primes the promoters of target genes in an epigenetic ABA‐dependent manner. Application of SA190 priming on crops is demonstrated for alfalfa, showing enhanced performance under drought conditions. In summary, a single beneficial root bacterial strain can help plants to resist drought conditions. Synopsis The beneficial root endophytic desert bacterium Pseudomonas argentinensis sp. SA190 enhances drought stress tolerance in Arabidopsis by priming target gene promoters in an epigenetic ABA‐dependent manner. SA190 modulates the expression of genes under drought stress in an ABA‐dependent manner. SA190 primes genes via H3K4me3 histone mark enrichment. SA190 alters host plant physiology by improving the plant water status. SA190 enhances crop performance under drought conditions. Graphical Abstract The beneficial root endophytic desert bacterium Pseudomonas argentinensis sp. SA190 enhances drought stress tolerance in Arabidopsis by priming target gene promoters in an epigenetic ABA‐dependent manner.