Non-target molecular network and putative genes of flavonoid biosynthesis in Erythrina velutina, a Brazilian semiarid native woody plant

Erythrina velutina is widely used in traditional medicine, being a source of specialized metabolites with anti-inflammatory and central nervous system modulatory activities. To date, the specialized metabolic network of the genus Erythrina and its regulation are missing, in part due to the lack of genomic information. In an effort to fill this knowledge gap, leaves and seeds had their metabolic and proteomic profiles (LC/MS) analyzed and integrated with transcriptome (RNA-seq) data. These data sets were obtained from plants growing in their harsh natural habitat and examined with emphasis on differentially expressed transcripts, transcription factors, and genes putatively involved in the biosynthesis of flavonoids, the most abundant metabolite class annotated. Of the 96 metabolites distributed in different classes found in this study, 28 and 30 were exclusively found in seeds and leaves, respectively, whereas 38 metabolites occurred in both structures. It was possible to assemble a set of 17,822 transcripts, of which 3,937 transcripts were differentially expressed (2,815 down- and 1,122 up-regulated). Candidate transcripts involved in flavonoid accumulation and transcription factors amounted to 28 and 394, respectively. Expression patterns of transcripts involved in flavonoid biosynthesis and its regulation, as well as those involved in responses to biotic and abiotic stresses, are discussed in detail. Hopefully, these findings will provide a solid base to further the understanding of the molecular and metabolic responses in this important medicinal plant species, as well as identify key regulatory targets for future studies aiming at bioactive metabolite production.