Qingfang Wen

Pectin methylesterases (PMEs) and their inhibitors (PMEIs) serve as pivotal enzymes in pectin methylation modifications, playing crucial roles in plant morphogenesis, cell adhesion, and maintenance of the cell wall integrity. However, there have been limited studies exploring the functions of the PME/PMEI gene families in the healing process of grafted-cucumber seedlings and their responses to stress conditions. In this study, we identified 52 CsaPME family members and 33 CsaPMEI family members as well as 86 CmoPME family members and 36 CmoPMEI family members. Comprehensive analyses of the PME/PMEI gene families in cucumber and pumpkin were conducted using bioinformatics techniques. Additionally, the PME/PMEI gene families in cucumber and pumpkin exhibited distinct expression modes in different vegetative organs of homologous/heterologous-grafted seedlings and under chilling stress. Notably, the cucumber/pumpkin-grafted seedlings exhibited responses in the roots and leaves involving PMEI and type I proPME genes, facilitating their adaptation to chilling stress. Additionally, an investigation into the responsiveness of cucumber/pumpkin-grafted seedlings during the healing phase to varying light intensity modes revealed that the implementation of a higher light intensity mode resulted in an upregulation of the expression levels of the majority of PME/PMEI family genes, particularly those belonging to the PME family, during the critical stages of isolation layer and callus formation. Based on these findings, six key PME/PMEI family members responsive to different light intensity modes during graft healing were selected. Through the prediction of transcription factor binding sites and an analysis of the response to different light intensity modes during graft healing, four Dof transcription factors with potential regulatory relationships with these six key PME/PMEI genes were identified. This suggests that cucumber/pumpkin-grafted seedlings can regulate key PME/PMEI genes via Dof factors in response to different light intensity modes during the healing process, thereby influencing the progression of graft healing.

Insights into flavor formation during fruit ripening can guide the development of breeding strategies that balance consumer and producer needs. Cherry tomatoes possess a distinctive taste, yet research on quality formation is limited. Here, metabolomic and transcriptomic analyses were conducted on different ripening stages. The results revealed differentially accumulated metabolites during fruit ripening, providing candidate metabolites related to flavor. Interestingly, several key flavor-related metabolites already reached a steady level at the mature green stage. Transcriptomic analysis revealed that the expression levels of the majority of genes tended to stabilize after the pink stage. Enrichment analysis demonstrated that changes in metabolic and biosynthetic pathways were evident throughout the entire process of fruit ripening. Compared to disease resistance and fruit color genes, genes related to flavor and firmness may have a broader impact on the accumulation of metabolites. Furthermore, we discovered the interconversion patterns between glutamic acid and glutamine, as well as the biosynthesis patterns of flavonoids. These findings contribute to our understanding of fruit quality formation mechanisms and support breeding programs aimed at improving fruit quality traits.