Variations in phyllosphere microbial community along with the development of angular leaf-spot of cucumber

Abstract

The phyllosphere is colonized by a wide variety of microorganisms including epiphytes, plant-pathogenic fungus, bacteria, as well as human or animal pathogens. However, little is known about how microbial community composition changes with the development of angular leaf-spot of cucumber. Here, 18 mixed samples were collected based on the lesion coverage rate (LCR) of angular leaf-spot of cucumber from three disease severity groups (DM1: symptomatic-mild, DM2: symptomatic-moderate, DM3: symptomatic-severe). In our study, the microbial community structure and diversity were examined by Illumina MiSeq sequencing. A significant differences was observed in α diversity and community structure among three disease severity groups. The phyllosphere microbiota was observed to be dominated by bacterial populations from Proteobacteria, Actinobacteria, and Firmicutes, as well as fungal species from Ascomycota and Basidiomycota. In addition, some plant-specific microbe such as Sphingomonas , Methylobacterium , Pseudomonas , and Alternaria showed significant changes in their relative abundance of population. The LCR was correlated negatively with Sphingomonas , Methylobacterium , Quadrisphaera , and Lactobacillus , whereas correlated positively with Pseudomonas and Kineococcus (p < 0.05). The LCR was negatively correlated with Alternaria and Arthrinium of the fungal communities (p < 0.05). Molecular ecological networks of the microbial communities were constructed to show the interactions among the OTUs. Our current results indicated that the competitive relationships among species were broken with the development of angular leaf-spot of cucumber. The microbial community composition changed over the development of angular leaf-spot of cucumber. The result of molecular ecological networks indicated that the overall bacterial community tends toward mutualism from the competition. The development of angular leaf-spot of cucumber affected the ecosystem functioning by disrupting the stability of the microbial community network. This work will help us to understand the host plant-specific microbial community structures and shows how these communities change throughout the development of angular leaf-spot of cucumber. Electronic supplementary material The online version of this article (10.1186/s13568-019-0800-y) contains supplementary material, which is available to authorized users.

Shaping the leaf microbiota: plant–microbe–microbe interactions

“…Generally, higher community complexity in a network reflects a more stable community structure ( Mougi and Kondoh, 2012 ). Stable microbial communities or consortia have greater ability to resist perturbation ( Ives et al , 2000 ; Luo et al , 2019 ; Morella et al , 2020 ). Studies using culture-independent DNA sequencing revealed similar microbial community patterns in successive year samplings ( Copeland et al.…”

“…Much less is known about the dynamics and stability of leaf microbiomes in the field since there is a lack of high-resolution experimental data linked to plant disease and health with respect to time, space, and environmental scale. In recent studies, leaf diseases were linked to disruption of microbial community network stability, resulting in ecosystem dysfunction ( Kerdraon et al , 2019 ; Luo et al , 2019 ; Leopold and Busby, 2020 , Preprint). Understanding how a microbial community corrects itself under conditions of environmental stress is crucial to harness its potential in probiotic applications against aggressive plant pathogens and to track plant-associated human pathogen outbreaks.…”

Fungal Composition and Diversity of the Tobacco Leaf Phyllosphere During Curing of Leaves

“…Many studies have examined the correlation between the microbiome and plant disease, showing that the microbiome could be disease suppressive or conducive (Luo et al, 2019;Raza et al, 2019). OTU (Operational Taxonomic Units) biodiversity analysis of phyllosphere microbiome has been reported for during several tobacco diseases, including black shank, brown spot and pole rot of tobacco (Chen et al, 2019;Xiang et al, 2019;Liu et al, 2020).…”

Modes of Action of Microbial Biocontrol in the Phyllosphere

“…However, they have been shown to dominate the endosphere of Origanum vulgare plants (Pontonio et al, 2018) and have been correlated negatively with disease symptoms of leaf spot on cucumber plants, presumably caused by P. syringae pv. lachrymans (Luo et al, 2019). Next to the production of hydrolytic enzymes by the biocontrol agents themselves, microbes can induce the production of chitinases in the host plant, a common defense reaction in plants.…”