The transcriptomic analysis revealed the molecular mechanism of Arbuscular Mycorrhizal Fungi (AMF) inoculation in watermelon

Arbuscular mycorrhizal fungi (AMFs) and plants have a symbiotic relationship that facilitates nutrient accumulation for plant development and productivity. However, the molecular mechanism through which AMF controls the growth and development of plants is still largely unknown. In this study, the physiological and transcriptional responses of watermelon seedlings with and without AMF inoculation were compared. AMF inoculation improved the assimilation and absorption of potassium, phosphorus, and nitrogen. When inoculated, watermelon development was considerably greater than that in the absence of inoculation. Several differentially expressed genes (DEGs) were identified after 64 days after AMF inoculation. Specifically, the metabolic and signal transduction pathways exhibited an abundance of key DEGs. Inoculated watermelons resulted in 2259 DEGs involved in photosynthesis, chlorophyll biosynthesis, hormone biosynthesis, and nutrient transporters. Based on these results, it appears that AMF may enhance seedling growth and nutrient accumulation by stimulating gene expression. Notably, inoculation affected auxin-responsive proteins, auxin response factors, auxin-induced proteins, auxin-mediated proteins, and auxin transporter-like proteins, all of which are components of the auxin signalling pathway. The physiological and molecular analyses in this study may shed light on the underlying mechanism by which AMF affects the growth and development of watermelon.