Transcriptional Regulation in Roots by Bacteria With 1-Aminocyclopropane-1-Carboxylate Deaminase Enzymes for Drought...

Plant growth-promoting rhizobacteria (PGPR) that can break down 1-aminocyclopropane-1-carboxylate (ACC), an ethylene precursor, by ACC deaminase enzymes (ACCd) to reduce ethylene production in plants may enhance plant tolerance to drought stress. This study aimed to identify genes in plant roots regulated by ACCd-bacteria under drought stress and re-watering and to determine major molecular factors and associated metabolic pathways for ACCd bacteria-enhanced drought tolerance and post-stress recovery in creeping bentgrass (Agrostis stolonifera). Transcriptomic analysis was performed in root tissues from plants inoculated with a novel strain of ACCd-producing bacteria, Paraburkholderia aspalathi "WSF23," under well-watered conditions, 35 days of drought stress, and 15 days of re-watering. ACCd bacteria inoculation resulted in differential expression of 53 genes under drought stress. Genes up-regulated in inoculated roots during drought stress included SUMO (small ubiquitin-like modifier) protease OTS1, an alcohol dehydrogenase (ADH2), desiccation-related protein (DRP) gene pcC-13362, cell wall structure and elasticity (TBL27), and antioxidant metabolism (DJ-1C and 1CYSPRXA). For post-drought recovery, inoculated plants differentially expressed 160 genes, including up-regulation of DNA repair (RAD6), signal transduction (WRKY72), root growth and development (D10, WRKY74, ERF3), nitrogen transport (DUR3), and osmoregulation (CIPK23), as well as up-regulation of carotenoid biosynthesis pathways. These findings help to explain the molecular mechanisms associated with ACCd bacteria-mediated drought stress tolerance and post-drought recovery in cool-season perennial grass species, contributing to sustainable methods of reducing water use in turfgrass management.