Superoxide dismutases (SODs), a family of antioxidant enzymes, are the first line of defense against oxidative damage and are ubiquitous in every cell of all plant types. The Cu/Zn SOD, one of three types of SODs present in plant species, is involved in many of the biological functions of plants in response to abiotic and biotic stresses. Here, we carried out a comprehensive analysis of the Cu/Zn SOD gene family in different plant species, ranging from lower plants to higher plants, and further investigated their organization, sequence features, and expression patterns in response to biotic and abiotic stresses. Our results show that plant Cu/Zn SODs can be divided into two subfamilies (group I and group II). Group II appeared to be conserved only as single- or low-copy genes in all lineages, whereas group I genes underwent at least two duplication events, resulting in multiple gene copies and forming three different subgroups (group Ia, group Ib, and group Ic). We also found that, among these genes, two important events—the loss of introns and the loss of and variation in signal peptides—occurred over the long course of their evolution, indicating that they were involved in shifts in subcellular localization from the chloroplast to cytosol or peroxisome and underwent functional divergence. In addition, expression patterns of Cu/Zn SOD genes from Arabidopsis thaliana and Solanum lycopersicum were tested in different tissues/organs and developmental stages and under different abiotic stresses. The results indicate that the Cu/Zn SOD gene family possesses potential functional divergence and may play vital roles in ROS scavenging in response to various stresses in plants. This study will help establish a foundation for further understanding these genes’ function during stress responses.

Chili pepper is an important vegetable and spice crop with high post-harvest deteriorations in terms of commercial and nutritional quality. Light-emitting diodes (LEDs) are eco-friendly light sources with various light spectra that have been demonstrated to improve the shelf-life of various vegetables by manipulating light quality; however, little is known about their effects on the post-harvest nutritional quality of chili peppers. This study investigated the effects of different LED lightings on the post-harvest firmness and nutritional quality of chili peppers. We found that red and blue light could increase the content of capsaicinoids, whereas white and red light could increase the essential and aromatic amino acid (AA) content in pepper. Nonetheless, the influence of light treatments on AA contents and compositions depends strongly on the pepper genotype, which was reflected by total AA content, single AA content, essential AA ratio, delicious AA ratio, etc., that change under different light treatments. Additionally, light affected fruit firmness and the content of nutrients such as chlorophyll, vitamin C, and total carotenoids, to varying degrees, depending on pepper genotypes. Thus, our findings indicate that LED-light irradiation is an efficient and promising strategy for preserving or improving the post-harvest commercial and nutritional quality of pepper fruit.

The commercial and nutritional quality of chili peppers deteriorates rapidly after harvest. So far, little is known about the effect of temperature on postharvest chili pepper quality. This study elucidated the effects of two temperatures (20 °C and 30 °C) on chili peppers’ postharvest firmness, flavor, and nutritional attributes. We found that compared to 20 °C, 30 °C escalated the decline in fruit firmness, capsaicin content, and dihydrocapsaicin content, while enhancing the increment in water loss and electrical conductivity, as well as total carotenoids and ascorbic acid content. The contents of most amino acids (AAs) decreased significantly during postharvest storage compared to their initial values, whether stored at 20 °C or 30 °C; however, 30 °C had a more substantial impact than 20 °C. Meanwhile, as for soluble protein and amino acid compositions, the effect of storage temperature was genotype-dependent, as reflected by differential changes in total AA contents, single AA contents, essential AA ratio, delicious AA ratio, etc., under the 20 °C or 30 °C treatments. In conclusion, our findings reveal the influence of temperature on pepper quality, showing that the storage temperature of 20 °C was better for maintaining chili quality than 30 °C from the perspective of overall commercial attributes.

Background: Phospholipase A (PLA) enzymes catalyze the hydrolysis of glycerophospholipids, releasing free fatty acids and lysophospholipids that play vital roles in plant growth, development, and stress responses. Methods: This study identified and analyzed SlPLA genes through bioinformatics and further explored the function of PLA genes under cold stress through virus-induced gene silencing (VIGS) experiments. Results: This study systematically characterized the SlPLA gene family in tomato, identifying 80 genes distributed across 12 chromosomes. Phylogenetic analysis categorized these genes into three groups: pPLA, PLA1, and PLA2. Conserved motifs and gene structure analysis revealed distinct patterns, with some genes lacking untranslated regions (UTRs), which suggests functional diversification. Promoter analysis indicated that SlPLA genes are regulated by light, hormones, and stress-related elements, particularly cold stress. RNA-seq data and qRT-PCR results indicated the differential expression of SlPLA genes across various tissues in tomato cultivars (Heinz and Micro-Tom). Under cold stress, certain SlPLA genes, especially SlPLA1-2, were up-regulated, suggesting their involvement in cold tolerance. Silencing SlPLA1-2 resulted in increased membrane damage, elevated malondialdehyde (MDA) levels, higher electrolyte leakage, and a lower expression of cold-responsive genes within the ICE1-CBF-COR pathway and jasmonic acid (JA) biosynthesis. Conclusions: This study discovered 80 SlPLA genes in tomato across 12 chromosomes, categorizing them into pPLA, PLA1, and PLA2 via phylogenetic analysis. The qRT-PCR analysis identified that SlPLA1-2 was strongly induced by cold stress, and further experiments regarding genetics and physiology revealed that SlPLA1-2 boosts the cold tolerance of tomato by affecting the CBF signaling pathway and JA biosynthesis, offering insights for future stress-resilience breeding.