Phenylpropanoids Accumulation in Eggplant Fruit: Characterization of Biosynthetic Genes and Regulation by a MYB Transcription Factor

• DOI: 10.3389/fpls.2015.01233
• Publication Date: 2016-01-28T06:20:29Z
• Authors: Teresa Docimo; Gianluca Francese; Alessandra Ruggiero; Giorgia Batelli; Monica De Palma; Laura Bassolino; Laura Toppino; Giuseppe L. Rotino; Giuseppe Mennella; Marina Tucci
• Keywords: Phenylpropanoid; MYB; Secondary metabolite

Phenylpropanoids are major secondary metabolites in eggplant (Solanum melongena) fruits. Chlorogenic acid (CGA) accounts for 70-90% of total phenolics flesh tissues, while anthocyanins mainly present the fruit skin. As a contribution to understanding peculiar accumulation these health-promoting eggplant, we report on metabolite abundance, regulation CGA and anthocyanin biosynthesis, characterization candidate biosynthetic genes S. melongena. Higher contents CGA, Delphinidin 3-rutinoside, rutin were found fruits compared other associated an elevated transcript abundance structural such as PAL, HQT, DFR, ANS, suggesting that active situ biosynthesis contributes tissues. Putative orthologs two PAL well variant MYB1 transcription factor showing identity with group six MYBs, isolated from Occidental melongena traditional variety demonstrated differ published sequences Asiatic varieties. In silico analysis SmPAL1, SmHQT1, SmANS, SmMyb1 promoters revealed presence several Myb regulatory elements unique TF, its involvement physiological roles beside phenylpropanoid regulation. Transient overexpression Nicotiana benthamiana leaves C-terminal truncated form (SmMyb1Δ9) resulted only agro-infiltrated leaves. A yeast two-hybrid assay confirmed interaction both SmMyb1Δ9 anthocyanin-related potato bHLH1 TF. Interestingly, doubled amount was detected leaves, thus N-terminal region is sufficient activate synthesis. These data suggest deletion does not limit capability regulate accumulation, but impairs biosynthesis. To our knowledge, this first study reporting functional elucidation role C-term conserved domain MYB activator proteins.