Physiological and Transcriptomic Dissection of Inflorescence Degeneration in Areca catechu L.: Aberrant Carbohydrate Redistribution and Disrupted Hormonal Homeostasis

Inflorescence degeneration in Areca catechu L. is characterized by growth arrest, tissue shrinkage and browning, ultimately compromising functional inflorescence formation and yield stability. To investigate its developmental window and regulatory basis, inflorescences from different leaf positions at the full-bloom stage were analyzed using anatomical observation, morphological measurements, carbohydrate and hormone assays, and RNA-seq-based transcriptomic analysis with qRT-PCR validation. Inflorescence degeneration was mainly concentrated in axillary inflorescences at the third and fourth leaf positions (BY3 and BY4). Compared with adjacent normal inflorescences, degenerated inflorescences showed reduced sucrose, starch and trehalose contents, increased ABA, JA and MeJA levels, and decreased cZR levels. Transcriptomic analysis revealed clear separation between degenerated and normal inflorescences, and differentially expressed genes were enriched in starch and sucrose metabolism, plant hormone signal transduction and transcriptional regulation. Co-expression network analysis identified modules associated with the degeneration window and key physiological traits, highlighting six candidate hub genes: AcAHP2, AcTIFY4B, AcTPS9-2, AcHXK2, AcWRKY3 and AcMPK1. These findings suggest that inflorescence degeneration is closely associated with carbon metabolic imbalance, hormone network remodeling and co-expression network reprogramming within a specific developmental window, providing a basis for future mechanistic studies and control strategies.