Rhizobacteria-enhanced drought tolerance and post-drought recovery of creeping bentgrass involving differential modulation of leaf and root metabolism

Rhizobacteria that produce 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase (ACCd) that inhibits ethylene production may mitigate stress damages. The objectives of this study were to examine whether a novel strain of ACCd-producing bacteria, Paraburkholderia aspalathi WSF23, promotes plant tolerance to drought stress and post-stress recovery and determine changes in metabolic profiles in leaves and roots associated with the positive ACCd-bacteria effects in cool-season perennial grass species. Creeping bentgrass (Agrostis Stolonifera L. cv. Penncross) plants were inoculated with P. aspalathi WSF23 and exposed to drought by withholding irrigation for 35 days, followed by re-watering for 15 days in growth chambers. Inoculated plants demonstrated increased turf quality, canopy density, and root growth during drought stress and more rapid re-growth upon re-watering. Metabolomic analysis demonstrated that inoculation with P. aspalathi WSF 23 increased the content of metabolites in the metabolic pathways related to stress defense, including osmoregulation, cell wall stability, and antioxidant protection in both leaves and roots, as well as nitrogen metabolism in roots of creeping bentgrass exposed to drought stress. The promotion of post-stress recovery by P. aspalathi WSF 23 was mainly associated with enhanced carbohydrate and pyrimidine metabolism and zeatin biosynthesis pathways in leaves and increased carbohydrates, biosynthesis of DNA and proteins, cellular metabolism, and TCA cycle activity in roots. These results provide insights into the metabolic pathways regulated by WSF23, with the PGPR conferring improvements in drought stress tolerance and post-drought recovery in a perennial grass species.

Automated summary

This study found that a novel strain of ACCd-producing bacteria, Paraburkholderia aspalathi WSF23, can enhance the growth and stress tolerance of grass species during drought and post-drought recovery. Metabolic analysis showed that inoculation with WSF23 increased the content of metabolites related to stress defense, nitrogen metabolism, carbohydrate and pyrimidine metabolism, zeatin biosynthesis, and cellular metabolism, which contributed to improved drought tolerance and post-drought recovery in the grass species.