Omics Analysis Unveils the Pathway Involved in the Purple Coloration in Tomato Seedling and Fruits

Abstract

AbstractThe purple tomato variety ‘Indigo Rose’(InR) is favored due to its bright appearance and abundant anthocyanins.SlHY5is associated with anthocyanin biosynthesis in ‘Indigo Rose’ plants. However, residual anthocyanins still present inSlhy5seedlings and fruit peel indicated there was an anthocyanin induction pathway that is independent of HY5 in plants. The molecular mechanism of color formation in ‘Indigo Rose’ andSlhy5mutants is unclear. In this study, we performed omics analysis to clarify the regulatory network underlying coloration in seedling and fruit peel of ‘Indigo Rose’ andSlhy5mutant. Results showed that the total amount of anthocyanins in both seedling and fruit of InR were significantly higher than those inSlhy5mutant and most genes associated with anthocyanin biosynthesis exhibited higher expression levels in InR, suggesting thatSlHY5play pivotal roles in flavonoid biosynthesis both in tomato seedlings and fruit. Yeast two-hybrid (Y2H) results revealed that SlBBX24 physically interacts with SlAN2-like and SlAN2, while SlWRKY44 could interact with SlAN11 protein. Unexpectedly, both SlPIF1 and SlPIF3 were found to interact with SlBBX24, SlAN1 and SlJAF13 by yeast two-hybrid assay. Suppression of SlBBX24 by virus-induced gene silencing (VIGS) retarded the purple coloration of the fruit peel, indicating an important role ofSlBBX24in the regulation of anthocyanin accumulation. These results deepen the understanding of purple color formation in tomato seedling and fruits in an HY5-dependent or independent manner via excavating the genes involved in anthocyanin biosynthesis based on omics analysis.