Insights into Candidate Pathways Associated with Multi-Pistil Formation in Chinese Chestnut (Castanea mollissima Bl.): Evidence from Anatomy, Physiology, and Molecular Biology

The number of pistils determines the yield of Chinese chestnut (Castanea mollissima Bl.). However, the candidate pathways associated with formation of multi-pistil female flower clusters (MFF) remain largely unclear. This study integrated morphological, anatomical, transcriptomic, and targeted phytohormone metabolomic approaches to compare MFF and normal female flower clusters (NFF). The results showed that MFF exhibited longer basal bracts with fewer basal trichomes. The critical stage for multi-pistil phenotype formation occurred during pistil primordium differentiation, when additional floral meristems continuously expanded and differentiated into new flower primordia. Auxin (IAA), cytokinin (CTK), jasmonic acid (JA), and gibberellin (GA) were identified as potentially associated with this. Candidate genes associated with hormone biosynthesis, signal transduction, and core transcription factors regulating floral organ development at this key developmental stage were also identified. The findings of this study provide insights into the potential regulatory mechanisms underlying the differentiation and development of MFF.