Coupled transcript and metabolite identification: insights on induction and synthesis of resveratrol in peanut, wild relatives and synthetic allotetraploid.
Resveratrol is an antioxidant that is a promising antitumoral, cardioprotective and neuroprotective agent. It has been found in a restricted number of plants including peanut (Arachis hypogaea L.) and its wild relatives. The objective of this study was to understand the relationship between resveratrol content and the expression of putative resveratrol synthase genes in four Arachis genotypes. Two diploids and two tetraploid were analyzed. Contents of resveratrol on non- and UV-treated leaves were estimated using HPLC. Resveratrol synthase (RS) was analyzed using RT-qPCR with primers developed in this study. Sequences of six Arachis species were amplified using two degenerated primer pairs that were designed based on Arachis and general RS available at GenBank. Those sequences were used to qPCR primers design. Test and control leaves were collected from plants cultivated in greenhouse and three biological replicates were evaluated for each genotype. The synthesis of resveratrol in leaves was induced by treatment with UV for 2.5 h. All genotypes studied synthesized resveratrol. Concentrations ranged from 193.66 µg/g in synthetic allotetraploid to 371.97 µg/g in A. duranensis. Natural and induced allotetraoploids showed lower levels of resveratrol than their diploid parents. Untreated samples did not produce significant amounts of resveratrol. The analysis of resveratrol content and levels of RS mRNA allowed the identification of one gene induced by the UV treatment. The data showed different amounts of RS in the different genotypes suggesting early and late response to the UV induction in the different species. The understanding of the variation found among species will help to identify species that have high resveratrol content and their ideal pos-induction times. This also will allow analysis of other tissues where high levels resveratrol would be very important, such as in seeds.