Root exposure to apple replant disease soil triggers local defense response and rhizoplane microbiome dysbiosis.

A soil column split-root experiment was designed to investigate the ability of apple replant disease (ARD)-causing agents to spread in soil. 'M26' apple rootstocks grew into a top layer of Control soil, followed by a barrier-free split-soil layer (Control soil/ARD soil). We observed a severely reduced root growth, concomitant with enhanced gene expression of phytoalexin biosynthetic genes and phytoalexin content in roots from ARD soil, indicating a pronounced local plant defense response.

Exploring microbial determinants of apple replant disease (ARD): a microhabitat approach under split-root design.

Apple replant disease (ARD) occurs worldwide in apple orchards and nurseries and leads to a severe growth and productivity decline. Despite research on the topic, its causality remains unclear. In a split-root experiment, we grew ARD-susceptible 'M26' apple rootstocks in different substrate combinations (+ARD: ARD soil; -ARD: gamma-irradiated ARD soil; and Control: soil with no apple history).

Root growth, function and rhizosphere microbiome analyses show local rather than systemic effects in apple plant response to replant disease soil.

Apple replant disease (ARD) is the phenomenon of soil decline occurring after repeated planting of apple trees at the same site. This study aimed to elucidate whether ARD is systemic, i.e.