Vineyard endogenous Myroides odoratimimus and Arthrobacter nicotinovorans have Plant Growth Promoting potential

Climate change is a pivotal challenge to Mediterranean viticulture, including that of the Douro Demarcated Region in Portugal. Identifying and using native beneficial microorganisms emerges as a sustainable, innovative strategy to help vineyards cope with increased temperature and/or drought. From a collection of ~ 400 native bacteria isolated from the Douro vineyards, the screening of siderophore production, phosphate solubilisation, IAA production, and ACCd activity showed that Myroides odoratimimus and Arthrobacter nicotinovorans were the most promising to act as plant growth promoters (PGP), distinguishing themselves by producing high levels of IAA, and by high phosphate-solubilising capacity, respectively. These strains were applied to the rhizosphere of grapevine plants, and showed positive effects by preventing or increasing the grapevines’ reactiveness to the impact of drought stress, on the oxidative disturbance, and the maintenance of the photosynthetic capacity, which permitted the maintenance of energy storage through TIS accumulation, contrary to the results observed in PGP-untreated grapevines subjected to drought stress. Our results demonstrate that enriching grapevines with native M. odoratimimus and A. nicotinovorans contributed, by different mechanisms of action, and with different impacts, to the plant’s defence against drought. These results could be promising towards the development of new strategies, namely the application of these PGP bacteria, to mitigate the impact of climate change on viticulture.