Effects of ρ-hydroxybenzoic acid on metabolism and excretion of grapevine root

Autotoxicity is a significant contributor to replant disease, with phenolic acid autotoxins such as 4-HBA (ρ-hydroxybenzoic acid) influencing the structure of the rhizosphere microbial community by modifying the secretion characteristics of grapevine roots. In the study, 'Beta' grape seedlings were selected to investigate the regulatory mechanism of 4HBA on root metabolism and secreting characteristics. The results showed that the expression level of genes related to primary and secondary metabolism in the roots was affected by 100 μg mL^-1 4-HBA treatment, and the genes related to starch and sucrose metabolism were generally down-regulated, and most genes encoding glycolytic pathway, amino acid pathway and phenylpropanoid biological pathway were up-regulated. A total of 142 metabolites were significantly changed after 100 μg mL^-1 4-HBA treatment, of which 92 metabolites were significantly up-regulated and 50 metabolites were significantly down-regulated. 7 amino acids, 3 phenolic acids, 2 nucleotides, 2 flavonoids, 4 organic acids, and 9 fatty acids might be regulated by ABC transporter. Further research found that some metabolites regulated by ABC transporter affected the growth of Fusarium solani, a harmful fungus related to grape replant disease. Our research confirmed that 4-HBA not only alters root metabolism but also modifies the content of root exudates, among which ABC transporters playing a crucial role in the efflux process.