Ziji Liu

Carotenoids contribute to photoprotection and abiotic stress adaptation in plants, and lycopene cyclases (LCYs) occupy a key branch point in carotenoid biosynthesis. However, the composition and stress-responsive divergence of LCY genes in pepper remain insufficiently characterized. In this study, we identified six CaLCY genes in Capsicum annuum and analyzed their structural features and expression patterns under drought and salt stress. CaLCYB1 showed the strongest and most consistent induction under both drought and salt stresses and was positively correlated with carotenoid accumulation, whereas the other CaLCY members exhibited distinct or negligible expression patterns. Transient overexpression of CaLCYB1 significantly increased β-carotene and total carotenoid contents by 117.6% and 45.1%, respectively, relative to the empty-vector control, and also augmented ABTS^•+ radical scavenging activity as well as ascorbate peroxidase (APX) activity. Conversely, virus-induced gene silencing (VIGS) of CaLCYB1 led to marked reductions in all of these parameters. Correlation analysis, together with gain- and loss-of-function assays, supports an important role of CaLCYB1 in carotenoid accumulation and β,β-branch-related antioxidant responses under stress. Yeast two-hybrid screening identified three potential interactors of CaLCYB1, namely CaUBQ, CaLHP1, and CaLARP6B. This study provides a family-level characterization of LCY genes in pepper and identifies CaLCYB1 as a major stress-responsive member that directs carotenoid flux and enhances antioxidant capacity under abiotic stress.

Chilling stress inhibits the growth of okra (Abelmoschus esculentus L.), reduces its overall agricultural yield, and deteriorates fruit quality. Therefore, it is crucial to elucidate the mechanism through which okra plants respond to chilling stress. This study investigates the molecular mechanisms of chilling tolerance by comparing the transcriptome and metabolome of chilling-tolerant (Ae182) and chilling-sensitive (Ae171) okra varieties. We found that Ae182 exhibits higher antioxidant enzyme activities, including SOD, POD, CAT, and APX, suggesting it mitigates oxidative stress more effectively than Ae171. Metabolomics analysis revealed that Ae182 produces higher levels of jasmonic acid (JA) and JA-isoleucine (JA-Ile) under chilling stress, potentially activating genes that alleviate oxidative damage. Additionally, integrated analyses identified key transcription factors, such as AP2, BHLH, and MYB, associated with JA and chilling stress. These findings provide candidate genes for further research on chilling resistance in okra.

TCP transcription factors play a key role in regulating various developmental processes, particularly in shoot branching, flower development, and leaf development, and these factors are exclusively found in plants. However, comprehensive studies investigating TCP transcription factors in pepper (Capsicum annuum L.) are lacking. In this study, we identified 27 CaTCP members in the pepper genome, which were classified into Class I and Class II through phylogenetic analysis. The motif analysis revealed that CaTCPs in the same class exhibit similar numbers and distributions of motifs. We predicted that 37 previously reported miRNAs target 19 CaTCPs. The expression levels of CaTCPs varied in various tissues and growth stages. Specifically, CaTCP16, a member of Class II (CIN), exhibited significantly high expression in flowers. Class I CaTCPs exhibited high expression levels in leaves, while Class II CaTCPs showed high expression in lateral branches, especially in the CYC/TB1 subclass. The expression profile suggests that CaTCPs play specific roles in the developmental processes of pepper. We provide a theoretical basis that will assist in further functional validation of the CaTCPs.

Plant cytochrome P450 is a multifamily enzyme widely involved in biochemical reactions for the synthesis of antioxidants, pigments, structural polymers, and defense-related compounds. Pepper (Capsicum annuum L.) is an economically important plant. A comprehensive identification and characterization of P450 genes would provide valuable information on the evolutionary relationships of genes and their functional characteristics. In this study, we identified P450 genes in pepper with the aid of bioinformatics methods to investigate the phylogenetic relation, gene structure, chromosomal localization, duplicated events, and collinearity among Solanaceae species. We identified and classified 478 genes of P450 from the pepper genome into two major clades and nine subfamilies through phylogenetic analysis. Massive duplication events were found in the P450 gene family, which may explain the expansion of the P450 gene family. In addition, we also found that these duplication genes may have undergone strict purification selection during evolution. Gene expression analysis showed that some P450 genes that belong to clan 71 in pepper may play an important role in placenta and pericarp development. Through quantitative real-time polymerase chain reaction and transcriptome analysis, we also found that many P450 genes were related to defensive and phytohormone response in pepper. These findings provide insight for further studies to identify the biological functions of the P450 genes in pepper.