Insight into the Bacterial Endophytic Communities of Peach Cultivars Related to Crown Gall Disease Resistance

Abstract

Crown gall disease caused by Agrobacterium tumefaciens severely impacts the production of peach and other fruit trees. Several peach cultivars are partially resistant to A. tumefaciens, but little is known about the roles of endophytic microbiota in disease resistance. In the present study, the endophytic bacterial communities of resistant and susceptible peach cultivars "Honggengansutao" and "Okinawa" were analyzed using universal 16S rRNA gene amplicon sequencing in parallel with the cultivation and characterization of bacterial isolates. A total of 1,357,088 high-quality sequences representing 3,160 distinct operational taxonomic units (OTUs; Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes) and 1,200 isolates of 20 genera and 305 distinct ribotypes were collected from peach roots and twigs. It was found that factors including plant developmental stage, cultivar, and A. tumefaciens invasion strongly influenced the peach endophytic communities. The community diversity of endophytic bacteria and the abundance of culturable bacteria were both higher in the roots of the resistant cultivar, particularly after inoculation. Strikingly, the pathogen antagonists Streptomyces and Pseudomonas in roots and Rhizobium in twigs were most frequently detected in resistant plants. Our results suggest that the higher abundance and diversity of endophytic bacteria and increased proportions of antagonistic bacteria might contribute to the natural defense of the resistant cultivar against A. tumefaciens. This work reveals the relationships between endophytic bacteria and disease resistance in peach plants and provides important information for microbiome-based biocontrol of crown gall disease in fruit trees. IMPORTANCE Agrobacterium tumefaciens as the causal agent of peach crown gall disease can be controlled by planting resistant cultivars. This study profiles the endophytic bacteria in susceptible and resistant peach cultivars, advancing our understanding of the relationships between endophytic bacterial communities and peach crown gall disease, with potential implications for other complex microbiome-plantpathogen interactions. The resistant cultivar may defend itself by increasing the diversity and abundance of beneficial endophytic bacteria. The antagonists identified among the genera Streptomyces, Pseudomonas, and Rhizobium may have application potential for biocontrol of crown gall disease in fruit trees.

Organs, Cultivars, Soil, and Fruit Properties Affect Structure of Endophytic Mycobiota of Pinggu Peach Trees

“…Fungal communities of olive cultivars showed significant varied fungal richness and composition associated with the presence of olive pathogens causing leaf spots [64]. Two peach cultivars have different capacities for disease resistance, and with different bacterial communities, increased proportions of antagonistic bacteria might contribute to the natural defense of the resistant cultivar [65]. Regarding bahiagrass in the USA, the influence of cultivar selection on soil fungal and bacterial communities is low, although specific taxa appeared to be cultivar-dependent, which may has implications for the control of plant pathogens [66].…”

Cultivar-Dependent Variation of the Cotton Rhizosphere and Endosphere Microbiome Under Field Conditions

“…Plants depend upon beneficial interactions between roots and microbes for nutrient uptake, and improved tolerance to biotic and abiotic stress (Mendes et al, 2011;Berendsen et al, 2012;Zhang et al, 2019). Beneficial soil microbes contribute to pathogen resistance (Mendes et al, 2011;Berendsen et al, 2012), drought tolerance (Lau and Lennon, 2012), and promoting plant growth (Pii et al, 2015). In return, plants secrete up to 20% of their fixed carbon and 15% of their nitrogen into the rhizosphere, thus supporting microbial communities (Sasse et al, 2018).…”

<i>In vitro</i> Characterisation of Endophytic Fungi Strains from Lantana camara Leaves Displaying Antifungal Activity Against Phytophthora colocasiae

“…Secondly it could be because the strains L 3 produced an enzyme laccase which reduced the growth of P. colocasiae compared to the strain L 2 which did not produce laccase. Results obtained from the dual culture assays only showed direct antagonism that may be due to the production of antibiotics and/or lytic enzymes produced by endophytes [4].…”

“…The increasing public demands for reduction in pesticides used emphasizes the need for alternative disease control strategies. The new strategy is biology control using antagonist fungi susceptible to the dissemination of pathogen such as endophytic fungi [4]. Endophytes are organisms inhabiting plant organs that at some time in their life can colonize internal plant tissues without causing apparent harm to the host.…”