Tea plants are frequently threatened by insect pests, resulting in substantial yield and quality losses. Methyl jasmonate (MeJA) is a key defense signaling molecule in plants; however, its integrated effects on tea plant growth, resistance, and quality-related traits remain poorly understood. In this study, field experiments were conducted to evaluate the effects of exogenous MeJA at different concentration (0.02–20 mM) on growth traits, quality components, and resistance to the tea green leafhopper and tea orange gall mite in Camellia sinensis ‘Zhongcha 108’, and transcriptome analysis was further integrated to elucidate the underlying molecular mechanisms. The results showed that appropriate MeJA concentrations (0.2–2 mM) significantly optimized bud morphology, characterized by shortened internodes, thicker stems, and reduced leaf insertion angles. Importantly, these treatments did not significantly alter the measured quality-related biochemical components, such as free amino acids and soluble sugars, within the evaluated time frame. Collectively, this study provides the first field-based evidence defining an effective MeJA concentration window that balances pest resistance induction, growth modulation, and processing suitability for flat-type green tea, offering practical guidance for the rational application of MeJA in tea plantation management.

Frequent strain degeneration during subcultivation, characterized by impaired sporulation and fruiting body formation, represents a major constraint in fungal agricultural production. Our study systematically investigated two naturally degenerated Lentinula edodes strains classified as abortive (Abt: L808-13, L808-14) and malformed (Abn: L808-18) fruiting-body phenotypes, through comprehensive phenotypic characterization, enzymatic profiling, thermotolerance assessment, and transcriptomic analysis. While vegetative growth remained unaffected, degenerated strains exhibited premature hyphal knotting, significantly reduced thermotolerance, and Abn-specific suppression of carboxymethyl cellulase (CMCase) activity. Comparative transcriptomics revealed 1239 and 582 differentially expressed genes (DEGs) in Abt and Abn groups, respectively, accompanied by a global dysregulation in carbohydrate catabolism, phospholipid metabolism, and redox homeostasis. Furthermore, protein–protein interaction (PPI) networks and RT-qPCR data highlighted 12 core hub genes enriched in glycoside hydrolysis, cytochrome P450 signaling, and membrane lipid dynamics. These findings provide mechanistic insights into the molecular basis of fruiting body degeneration and establish a foundation for developing diagnostic indicators to screen for early-stage degeneration in industrial mushroom production.