Exogenous ethylene is commonly utilized to initiate flower induction in pineapple (Ananas comosus (L.) Merr.). However, the molecular mechanisms and metabolic changes involved are not well understood. In this study, we explored the genetic network and metabolic shifts in the ‘Comte de Paris’ pineapple variety during ethylene-induced flowering. This was achieved through an integrative analysis of metabolome and transcriptome profiles at vegetative shoot apexes (0 d after ethephon treatment named BL_0d), the stage of bract primordia (8 d after ethephon treatment named BL_8d), stage of flower primordia (18 d after ethephon treatment named BL_18d), and the stage of stopped floret differentiation (34 d after ethephon treatment named BL_34d). We isolated and identified 804 metabolites in the pineapple shoot apex and inflorescence, categorized into 24 classes. Notably, 29, 31, and 46 metabolites showed significant changes from BL_0d to BL_8d, BL_8d to BL_18d, and BL_18d to BL_34d, respectively. A marked decrease in indole was observed, suggesting its role as a characteristic metabolite during flower induction. Transcriptomic analysis revealed 956, 1768, and 4483 differentially expressed genes (DEGs) for BL_0d vs. BL_8d, BL_8d vs. BL_18d, and BL_18d vs. BL_34d, respectively. These DEGs were significantly enriched in carbohydrate metabolism and hormone signaling pathways, indicating their potential involvement in flower induction. Integrating metabolomic and transcriptomic data, we identified several candidate genes, such as Agamous-Like9 (AGL9), Ethylene Insensitive 3-like (ETIL3), Apetala2 (AP2), AP2-like ethylene-responsive transcription factor ANT (ANT), and Sucrose synthase 2 (SS2), that play potentially crucial roles in ethylene-induced flower induction in pineapple. We also established a regulatory network for pineapple flower induction, correlating metabolites and DEGs, based on the Arabidopsis thaliana pathway as a reference. Overall, our findings offer a deeper understanding of the metabolomic and molecular mechanisms driving pineapple flowering.

Pineapple is one of the most important crops in tropical and subtropical areas. However, its production has been seriously impacted by the issue of fruit translucency in the past several decades. Fruit translucency is a physiological disorder of pineapple flesh with water-soaked core which results in a decline in pineapple quality. It has become a significant challenge for the sustainability of pineapple industry. Currently, the cause and pathophysiological development of pineapple translucency still have not been fully understood. The preventative and remedial measurements on the disease have yet to be effectively implemented in the production process. This review provides comprehensive information and the latest research progress on the possible pathogenesis, initiating factors, preventive and control practices, and detection techniques for pineapple translucency. Furthermore, the progress of research on apple and pear fruit translucency in recent years is reviewed and compared with pineapple translucency. The review offers theoretical guidance and insightful knowledge for the investigation of pineapple translucency disease.

Seasonal drought constitutes a major abiotic stress limiting the growth and yield of pineapple, a globally important Crassulacean acid metabolism (CAM) crop. The sucrose catabolism mediated by cell wall invertase (CWIN) plays a vital role in regulating plant growth and development, as well as adaptive responses to abiotic stresses. Invertase inhibitors (INHs) serve as specific post-translational regulators that modulate CWIN enzymatic activity. However, the INH family has not been systematically characterized in pineapple, and its functional roles in mediating sucrose metabolism and drought resistance remain elusive. In this study, three AcINHs were identified from the pineapple genome, followed by comprehensive analyses of their gene structures, phylogenetic relationships, homology characteristics and protein structures. Structural analysis revealed that all AcINH members harbor conserved motifs 1, 2, 3, 5 and 9, whereas only AcINH3 possesses motif 7. Expression analysis showed that only AcINH3 was significantly transcriptionally induced by drought stress among all family members. Functional validation demonstrated that AcINH3 knockout markedly elevated CWIN activity in pineapple seedling leaves, facilitating hexose accumulation and promoting plant growth and development. Moreover, AcINH3-edited lines exhibited enhanced drought resistance, accompanied by increased accumulation of soluble sugars (sucrose, glucose, fructose), abscisic acid (ABA), and proline (PRO), reduced malondialdehyde (MDA) content, and enhanced peroxidase (POD) activity. Biochemical assays further verified a direct physical interaction between AcINH3 and AcCWIN1, which mediates sucrose metabolism and drought stress responses. Collectively, this study identifies a novel AcINH3–AcCWIN1 post-translational module that modulates sugar metabolism and drought tolerance in pineapple, providing critical mechanistic insights for CAM plants. Our findings highlight AcINH3 as a promising target for genome-editing breeding to enhance drought resistance in CAM crops.