Abstract:

Phytoplasma is a bacterial pathogen that induces a range of symptoms in host plants， including yellowing， apical necrosis， witches’ broom， phyllody， dwarfism， and floral changes. In China， more than 100 types of phytoplasma diseases have been identified that affect important economic crops， traditional Chinese medicinal herbs， and forestry. Witches’ broom disease， caused by phytoplasma infection in Sophora alopecuroides， inhibits growth， causes seed production failure， and reduces yield， posing a potential threat to industries that utilize S. alopecuroides in China. This study focused on the impact of phytoplasma infection on S. alopecuroides metabolites by comparing infected and healthy plants using morphological， molecular biological， and untargeted metabolomic analyses. Our results indicate that the phytoplasma strain causing witches’ broom disease in S. alopecuroides belongs to the 16Sr V-B subgroup. Infection significantly altered the metabolite profile of S. alopecuroides， with differentially annotated metabolites primarily associated with environmental information processing， genetic information processing， and metabolism， with the latter constituting 92.38% of total observed metabolite changes. KEGG pathway analysis revealed significant differences in the porphyrin and chlorophyll metabolism pathways as well as in the biosynthesis of phenylalanine， tyrosine， and tryptophan. It is speculated that phytoplasma infection may induce disease symptoms in the host plant primarily through changes in host metabolites. Alterations in these two pathways play a crucial role in the occurrence of witches’ broom disease in S. alopecuroides， suggesting that infection reduces the photosynthetic capacity of the host， leading to nutrient deficiency and decreased resistance， which in turn aids disease progression.

Key words: Sophora alopecuroides, witches’ broom disease, non-targeted metabolomics, KEGG analysis