Genome-Wide Analysis of R2R3-MYB Genes and Functional Characterization of SmMYB75 in Eggplant Fruit Implications for Crop Improvement and Nutritional Enhancement

Abstract

R2R3-MYB represents a substantial gene family that plays diverse roles in plant development. In this study, 102 SmR2R3-MYB genes were identified from eggplant fruit and classified into 31 subfamilies. Analysis indicated that segmental duplication events played a pivotal role in the expansion of the SmR2R3-MYB gene family. Furthermore, the prediction of miRNAs targeting SmR2R3-MYB genes revealed that 60 SmR2R3-MYBs are targeted by 57 miRNAs, with specific miRNAs displaying varying numbers of target genes, providing valuable insights into the regulatory functions of miRNAs in plant growth, development, and responses to stress conditions. Through expression profile analysis under various treatment conditions, including low temperature (4 °C), plant hormone (ABA, Abscisic acid), and drought stress (PEG, Polyethylene glycol), diverse and complex regulatory mechanisms governing SmR2R3-MYB gene expression were elucidated. Notably, EGP21875.1 and EGP21874.1 exhibited upregulation in expression under all treatment conditions. Transcriptome and metabolome analyses demonstrated that, apart from anthocyanins (delphinidin-3-O-glucoside, cyanidin-3-O-(6-O-p-coumaroyl)-glucoside, and malvidin-3-O-(6-O-p-coumaroyl)-glucoside), overexpression of SmMYB75 could also elevate the content of various beneficial compounds, such as flavonoids, phenolic acids, and terpenes, in eggplant pulp. This comprehensive study enhances our understanding of SmR2R3-MYB gene functions and provides a strong basis for further research on their roles in regulating anthocyanin synthesis and improving eggplant fruit quality.

Genetic and Biotechnological Approaches to Improve Fruit Bioactive Content: A Focus on Eggplant and Tomato Anthocyanins

“…Yeast one and two-hybrid analyses indicated that SmMYB75 binds to the SmCHS gene’s promoter region and also interacts with SmTT8, a bHLH protein [ 84 ]. Overexpression of SmMYB75 resulted in plants with increased anthocyanin content in all tissues, including eggplant flesh, and differential expression of several anthocyanin pathway genes [ 85 ].…”

“…Despite the wealth of our current knowledge, it is clear that much still remains to be discovered about eggplant MYB genes. Shi et al [ 85 ] identified 102 R2R3-MYB genes in the genome and hypothesized that segmental duplication was the primary mechanism driving their evolution. In addition, miRNAs were identified that were predicted to target these TF genes.…”