Abstract

Drought is the main environmental factor limiting crop productivity. Since the rhizosphere microbiota appears to be part of the plants’ adaptive process to cope with drought, we aimed to evaluate the rhizobacterial microbiomes of thoroughly selected tolerant and susceptible tomato cultivars to water deficit by High-Throughput Meta-barcoding Sequencing (HTS). We observed an increase in the diversity of the bacterial community in response to water deficit in susceptible plants, but not in tolerant cultivars, suggesting that bacterial diversity is affected by the lack of water depending on the cultivar’s phenotype. Also, the rhizosphere bacterial communities grouped together irrespective of their plant cultivar or irrigation treatment but separated from the bulk soils, highlighting an overall evident “plant effect” in the bacterial composition of the soil. Instead, the diversity and clustering of the fungal communities did not show an association between the soil compartment, irrigation treatment, or plant cultivar. Nevertheless, over- represented specific bacterial and fungal taxa in the tolerant cultivar in response to water deficit were identified, suggesting an effect of these microorganisms in the adaptation of tomatoes to water scarcity. Finally, network analysis revealed that fungi greatly impacted the ecological interactions in the tolerant cultivar rhizosphere, implying that this rhizosphere contained the most advantageous interactions for the host due to a robust cooperation between intra-kingdom members and inter-kingdom biocontrol potential in response to water deficit. This study gives the first insights into the impact of plants differentially adapted to water deficit over the composition and interaction patterns of their rhizosphere microbial communities.