Improved plant resistance to drought is promoted by the root‐associated microbiome as a water stress‐dependent trait

Abstract

Although drought is an increasing problem in agriculture, the contribution of the root-associated bacterial microbiome to plant adaptation to water stress is poorly studied. We investigated if the culturable bacterial microbiome associated with five grapevine rootstocks and the grapevine cultivar Barbera may enhance plant growth under drought stress. Eight isolates, over 510 strains, were tested in vivo for their capacity to support grapevine growth under water stress. The selected strains exhibited a vast array of plant growth promoting (PGP) traits, and confocal microscopy observation of gfp-labelled Acinetobacter and Pseudomonas isolates showed their ability to adhere and colonize both the Arabidopsis and grapevine rhizoplane. Tests on pepper plants fertilized with the selected strains, under both optimal irrigation and drought conditions, showed that PGP activity was a stress-dependent and not a per se feature of the strains. The isolates were capable of increasing shoot and leaf biomass, shoot length, and photosynthetic activity of drought-challenged grapevines, with an enhanced effect in drought-sensitive rootstock. Three isolates were further assayed for PGP capacity under outdoor conditions, exhibiting the ability to increase grapevine root biomass. Overall, the results indicate that PGP bacteria contribute to improve plant adaptation to drought through a water stress-induced promotion ability.

Root-associated bacteria promote grapevine growth: from the laboratory to the field

“…We recognize that the colonization patterns observed in Arabidopsis may not reflect the one occurring in grapevine, but provide hints of the general process of root colonization. Our fluorescent screens on plant roots confirmed that the assayed bacteria were able to colonise the root systems of the plants as previously observed by Rolli et al (2015). Moreover, bacteria may became endophytic and moving from the interior of the roots to other plant tissues (Compant et al 2010;Compant et al 2011;Lareen et al 2016).…”

“…The roots inoculated with the B5-gfp and B7-dsRED strains were gently removed from the soil and analysed under the laser-scanning confocal microscope as described for the experiments with Arabidopsis. Finally, the bacteria in the grapevine rhizosphere was analysed using denaturing gradient gel elecrophoresis (DGGE) as described by Rolli et al (2015). The DGGE bands were excised from the gel using a sterile cutter and eluted in 50 μl of water at 37°C for 5 h. The reamplification of DNA eluted from the DGGE bands was performed using 907R and 357F primers without GC-clamps according to the following protocol: 95°C for 5 min, 30 cycles at 95°C for 1 min, 61°C for 1 min, 72°C for 1 min and a final extension at 72°C for 7 min.…”

“…These powerful properties have been shown at laboratory scale using in vitro assays (Zamioudis et al 2013;Salomon et al 2014) , soil microcosm tests (Sabir et al 2012;Suarez et al 2015), and field-like conditions (Shishido 1996;Chanway 1997;Aslantas et al 2007;Magnin-Robert et al 2013;Rolli et al 2015). However, the role these symbionts play in field-scale agricultural environments remains poorly understood (Bashan et al 2014 and reference therein; Berger et al 2015;GarciaSeco et al 2015;Garima and Nath 2015).…”

“…These bacteria can migrate from the root to the shoot of grapevine (Compant et al 2010;Compant et al 2011) surviving in the fruit (Bokulich N et al 2014;Gilbert J et al 2014). Moreover, recent works demonstrated how grape tissues can be colonized by both autochthonous and allochthonous bacteria (Compant et al 2013;Rolli et al 2015).…”

Assembly of seed-associated microbial communities within and across successive plant generations

“…The plant microbiota can influence multiple plant traits such as biomass accumulation (Sugiyama et al 2013), metabolite production , drought tolerance (Lau and Lennon 2012;Rolli et al 2015), flowering time (Wagner et al 2014;PankeBuisse et al 2015;Dombrowski et al 2017) and disease resistance (Busby et al 2016;Ritpitakphong et al 2016;Mendes et al 2011;Santhanam et al 2015).…”