Caffeoylquinic Acids Biosynthesis and Accumulation in Cynara cardunculus: State of the Art

Plant secondary metabolites are highly evolved compounds performing different functions, and have been widely exploited from food to medicine. A constant supply of phenols, a class of secondary metabolites, provides preventive and defensive mechanisms to reduce the risk of chronic diseases in human beings; among them mono- and di-caffeoylquinic acids (monoCQAs, diCQAs) have attracted a growing academic and industrial interest in recent years. In Cynara cardunculus L. the biosynthetic pathway of chlorogenic acid (CGA, 5-O-caffeoylquinic acid) has been the subject of our several recent studies. Here, we report the state of the art on the isolation and in vitro functional characterization of the genes involved in the biosynthetic pathway of the CGA: HCT (hydroxycinnamoyl-CoA shikimate/quinate hydroxycinnamoyl-transferase), HQT (hydroxycinnamoyl-CoA quinate hydroxyl-cinnamoyl-transferase), two HQT-like genes, we named Acyltransf_1 and Acyltransf_2, and C3’H (p-coumaroyl ester 3’-hydroxylase). Plant phenolics are known to be involved in the plant stress response and we found out that in globe artichoke the exposure to UV-C induces the production of diCQAs. In UV-C treated globe artichoke leaves, the expression level of C3´H, HCT, HQT, Acyltransf_1, Acyltransf_2 genes was strongly increased, thus confirming their involvement in the synthesis of chlorogenic acid. The development of DNA-based markers for the isolated genes made it possible to locate them within the previously developed genetic maps of the species

Transcriptome characterization and polymorphism detection between subspecies of big sagebrush (Artemisia tridentata)

<p>Abstract</p> <p>Background</p> <p>Big sagebrush (<it>Artemisia tridentata</it>) is one of the most widely distributed and ecologically important shrub species in western North America. This species serves as a critical habitat and food resource for many animals and invertebrates. Habitat loss due to a combination of disturbances followed by establishment of invasive plant species is a serious threat to big sagebrush ecosystem sustainability. Lack of genomic data has limited our understanding of the evolutionary history and ecological adaptation in this species. Here, we report on the sequencing of expressed sequence tags (ESTs) and detection of single nucleotide polymorphism (SNP) and simple sequence repeat (SSR) markers in subspecies of big sagebrush.</p> <p>Results</p> <p>cDNA of <it>A. tridentata </it>sspp. <it>tridentata </it>and <it>vaseyana </it>were normalized and sequenced using the 454 GS FLX Titanium pyrosequencing technology. Assembly of the reads resulted in 20,357 contig consensus sequences in ssp. <it>tridentata </it>and 20,250 contigs in ssp. <it>vaseyana</it>. A BLASTx search against the non-redundant (NR) protein database using 29,541 consensus sequences obtained from a combined assembly resulted in 21,436 sequences with significant blast alignments (≤ 1e^-15). A total of 20,952 SNPs and 119 polymorphic SSRs were detected between the two subspecies. SNPs were validated through various methods including sequence capture. Validation of SNPs in different individuals uncovered a high level of nucleotide variation in EST sequences. EST sequences of a third, tetraploid subspecies (ssp. <it>wyomingensis</it>) obtained by Illumina sequencing were mapped to the consensus sequences of the combined 454 EST assembly. Approximately one-third of the SNPs between sspp. <it>tridentata </it>and <it>vaseyana </it>identified in the combined assembly were also polymorphic within the two geographically distant ssp. <it>wyomingensis </it>samples.</p> <p>Conclusion</p> <p>We have produced a large EST dataset for <it>Artemisia tridentata</it>, which contains a large sample of the big sagebrush leaf transcriptome. SNP mapping among the three subspecies suggest the origin of ssp. <it>wyomingensis </it>via mixed ancestry. A large number of SNP and SSR markers provide the foundation for future research to address questions in big sagebrush evolution, ecological genetics, and conservation using genomic approaches.</p