Unraveling the Molecular Mechanisms Underlying Flat Stem Formation in Atractylodes lancea in Response to Phytoplasmas

Abstract Atractylodes lancea (Thunb.) DC has been widely used as a medicinal herb for centuries. However, long-term artificial cultivation of A. lancea led to serious plant diseases, such as the flat branch disease caused by phytoplasmas. To explore the formation mechanism of flat stems, we measured the changes in physiological and biochemical indicators and related metabolic pathways in stems of A. lancea in response to phytoplasma. After infection by pathogen, significant changes were observed in the content of stress compounds H2O2 and MDA, as well as the activities of antioxidant enzymes APX, POD, PPO, and CAT. The contents of jasmonic acid and zeatin in the flat stem (FS) of A. lancea increased significantly, while auxin content decreased. High-throughput sequencing showed that differentially expressed genes (DEGs) are enriched in hormone biosynthesis, signal transduction, Ca2+ signaling, and other pathways. These results preliminary elucidate the molecular mechanism of flat stem development in A. lancea, providing a foundation for disease prevention in the future.