Progressing towards eco-friendly agricultural management: Utilizing Ginkgo biloba leaf litter for potato common scab...

Soil ecological degradation intensifies soil-borne crop diseases. Employing eco-friendly and economical strategies to restore soil health is imperative for managing soil diseases. Here, we focused on potato common scab (PCS), a worldwide soil-borne disease caused by Streptomyces spp., and evaluated the suppression effects of Ginkgo leaf litter (GL) and its extract (GE), while elucidating their mechanisms. The results showed that both GL and GE significantly reduced the PCS disease index, with GL achieving over 50 % suppression in both pot and field trials. Both treatments effectively antagonized the PCS pathogen, reducing its relative abundance in bulk soil and geocaulosphere soil. The soil bacterial community was significantly correlated with the disease index, with the bacterial community in bulk soil making a particularly notable contribution to disease suppression, accounting for 52 % of the effect. Furthermore, GL and GE enhanced the stochastic processes in bacterial community assembly, and increased the complexity of bacterial co-occurrence networks. Notably, the microbial community restructured by GE significantly inhibited the expression of the pathogen's toxin gene, txtAB, decreasing its level from 10^4.5 copies per gram of soil to 10^2.1 copies, marking a decline exceeding two orders of magnitude. ASV339 (Aeromicrobium) and ASV932 (Achromobacter) were identified as key microbes, and their respective strains, Aeromicrobium OH2-5 and Achromobacter YD1-3, were isolated. The growth curve and biomass of these strains were positively influenced by GE, demonstrating Ginkgo leaves' enriching effect on beneficial microorganisms. These strains exhibited potent antagonistic activity against the PCS pathogen. Additionally, GE alleviated reactive oxygen species stress and up-regulated the defense-related gene PR1 in potato plants. This study validates the potential of Ginkgo leaf litter as a soil amendment additive for suppressing PCS and reveals its multifaceted mechanisms.