Experimental Evidence Pointing to Rain as a Reservoir of Tomato Phyllosphere Microbiota

Abstract

Plant microbiota play essential roles in plant health and crop productivity. Comparisons of community composition have suggested seeds, soil, and the atmosphere as reservoirs of phyllosphere microbiota. After finding that leaves of tomato (Solanum lycopersicum) plants exposed to rain carried a higher microbial population size than leaves of tomato plants not exposed to rain, we experimentally tested the hypothesis that rain is a so far neglected reservoir of phyllosphere microbiota. Rain microbiota were thus compared with phyllosphere microbiota of tomato plants either treated with concentrated rain microbiota, filter-sterilized rain, or sterile water. Based on 16S rRNA amplicon sequencing, one-hundred and four operational taxonomic units (OTUs) significantly increased in relative abundance after inoculation with concentrated rain microbiota but no OTU significantly increased after treatment with either sterile water or filter-sterilized rain. Some of the genera to which these 104 OTUs belonged were also found at higher relative abundance on tomatoes exposed to rain outdoors than on tomatoes grown protected from rain in a commercial greenhouse. Taken together, these results point to precipitation as a reservoir of phyllosphere microbiota and show the potential of controlled experiments to investigate the role of different reservoirs in the assembly of phyllosphere microbiota.

Genetic and Functional Diversity Help Explain Pathogenic, Weakly Pathogenic, and Commensal Lifestyles in the Genus Xanthomonas

“…The genus Xanthomonas , traditionally considered to group plant pathogenic bacteria, encompasses bacterial strains that, although they maintain close association with plants, do not cause apparent disease symptoms in their host of isolation ( Vauterin et al 1996 ; Essakhi et al 2015 ; Merda et al 2016 , 2017 ; Garita-Cambronero et al 2017 ; Martins et al 2020 ; Bansal et al 2021 ). Nonpathogenic xanthomonads have a varied lifestyle with the ability to colonize the plant hosts and survive in various environments outside the plants, such as rain and aerosols ( Vauterin et al 1996 ; Mechan Llontop et al 2021 ). Although referred to as nonpathogenic in the context of their phenotype based on artificial inoculation on the host of isolation, it cannot be ruled out that these strains may cause disease in other hosts.…”

Hydrological Perturbations Facilitated Phyllosphere Denitrification of an Urban Greening Tree

“…The trend that rainfalls within a season tend to enhance the relative abundances of phyllosphere CNPS cycling genes may be explained by two plausible mechanisms. First, the rainfall event is along with microbial mass dispersal carrying airborne microbial genes and cells onto the leaf surfaces for colonization. − Second, rainfalls could increase the mobility and accessibility of nutrients for the growth of phyllosphere microbiota and could also introduce external nutrients, such as precipitated N. , …”

Response of Phyllosphere and Rhizosphere Microbial Communities to Salt Stress of Tamarix chinensis

“…In addition, when salt scatters on the leaf surface and fills the grooves, the space in which the phyllosphere colonizers thrive is reduced, perhaps through competition to occupy ecological niches and increase access to limited resources [ 17 , 18 ]. Indeed, several studies on phyllosphere microbial communities have noted that rainfall reduces the bacterial spectrum of leaf microbial communities [ 19 , 20 ]. Furthermore, environmental factors such as wind, humidity, or ultraviolet radiation reduce the phyllosphere fungal diversity [ 21 ].…”