Mycorrhizal fungi enhance flooding tolerance of peach through inducing proline accumulation and improving root architecture

This study aimed to evaluate the effect of an arbuscular mycorrhizal fungus (AMF) Glomus mosseae on plant growth, root architecture, and proline metabolism in roots of peach (Prunes persica L.) under non-flooding and flooding conditions. The 12-day flooding dramatically inhibited root colonisation of G. mosseae, but induced a large number of extraradical mycelia. Although the flooding treatment also relatively inhibited growth and root architecture of peach, the mycorrhizal fungal inoculation dramatically increased shoot and root biomass, plant height, stem diameter, number of 1stand 2nd-order lateral roots, root total length (mainly 0-1 cm and > 3 cm long), root surface area, and root volume under flooding. The study also revealed distinctly higher proline accumulation in the roots of mycorrhizal plants than non-mycorrhizal plants under both non-flooding and flooding conditions, accompanied by higher Delta(1)-pyrroline-5-carboxylate synthase (P5CS) activity and lower delta-ornithine transaminase and proline dehydrogenase activities. In addition, the PpP5CS1 gene expression was up-regulated by flooding and mycorrhization. This study concluded that mycorrhizal fungi enhanced flooding tolerance of peach through inducing proline accumulation and improving root architecture.