Peach Gummosis Drives Spatially Structured Microbiome Dysbiosis with Stronger Disruption of Bacterial than Fungal Interaction Networks

Peach gummosis, primarily caused by Botryosphaeria dothidea, leads to progressive tree decline, yet how the host-associated microbiome differs between symptomatic and asymptomatic trees remains poorly understood. Sampling was conducted in a commercial orchard in Zaoyang, Hubei Province, China. Symptomatic trees were peach cultivar ‘Zhongtao 3’ and asymptomatic trees were nectarine cultivar ‘Qiuhongzhu’, grown in the same orchard. We profiled bacterial (16S rRNA) and fungal (ITS) communities from bulk soil, rhizosphere soil, root rhizoplane, root endosphere, basal and mid-trunk bark, and basal and mid-trunk xylem, and examined compositional shifts, predicted functional potential, and co-occurrence networks. Disease status significantly altered community composition in both kingdoms. Beta dispersion increased only in symptomatic trunk tissues, indicating that community destabilization is localized at the infection site. LEfSe and functional analyses showed that diseased tissues were depleted of biocontrol-relevant genera (Bacillus spp., Streptomyces spp.) and negatively correlated with function-predicted cellulolysis and iron respiration, while pathogen-associated fungi (Neocucurbitaria spp., Xenoacremonium spp., Neocosmospora spp.) were enriched. Co-occurrence networks revealed that bacterial networks were simpler in symptomatic trees: bacterial edge number declined by 39.0% versus 19.6% for fungi, accompanied by reduced cross-kingdom connectivity. Alpha diversity remained largely unchanged. These findings demonstrate that difference were spatially structured and taxonomically asymmetric erosion of interaction complexity rather than a uniform collapse of diversity. Bacterial connectivity in symptomatic tissues is a candidate target for microbiome-informed management of peach gummosis.