Chlorophyll degradation and carotenoid accumulation are essential processes of fruit maturation in many horticultural plants, and play a crucial role in fruit color and quality. The pathways of chlorophyll and carotenoid biosynthesis and degradation are well understood, and key regulatory genes controlling these pathways have been identified in citrus. This article reviewed the recent research on chlorophyll and carotenoid metabolism in citrus fruits, encompassing the metabolic pathways, transcriptional regulation, influencing factors, and the interplay between chlorophyll and carotenoid metabolism, aiming to provide insights into the molecular regulatory mechanisms governing the coloration of citrus fruits.

N⁶-methyladenosine (m⁶A) RNA modification is a conserved mechanism that regulates the fate of RNA across eukaryotic organisms. Despite its significance, a comprehensive analysis of m⁶A-related genes in non-model plants, such as kiwifruit, is lacking. Here, we identified 36 m⁶A-related genes in the kiwifruit genome according to homology and phylogenetic inference. We performed bioinformatics and evolutionary analyses of the writer, eraser, and reader families of m⁶A modification. Reanalysis of public RNA-seq data collected from samples under various biotic and abiotic stresses indicated that most m⁶A-related genes were remarkably expressed under different conditions. Through construction of gene co-expression networks, we found significant correlations between several m⁶A-related genes and transcription factors (TFs) as well as receptor-like genes during the development and ripening of kiwifruit. Furthermore, we performed ATAC-seq assays on diverse kiwifruit tissues to investigate the regulatory mechanisms of m⁶A-related genes. We identified 10 common open chromatin regions that were present in at least two tissues, and these regions might serve as potential binding sites for MADS protein, C2H2 protein, and other predicted TFs. Our study offers comprehensive insights into the gene family of m⁶A-related components in kiwifruit, which will lay foundation for exploring mechanisms of post-transcriptional regulation involved in development and adaptation of kiwifruit.