In yam, transcription profiles of leaf tissues from one anthracnose susceptible (TDa 95–0310) and two resistant yam genotypes (TDa 87–01091, TDa 95–0328) were analyzed upon infection with the anthracnose fungus a set of genes involved in defense against anthracnose were identified. Specially, it has been widely applied to investigate molecular mechanisms of color variation in plant species such as blueberry, grape, Brassica Juncea, and potato. Recently, transcriptomic analysis based on next generation sequencing (NGS) technology has emerged as an extremely powerful method for identifying novel genes associated with biosynthesis of various secondary metabolites in non-model plant species. also revealed that the loss of delphinidin (blue pigment) resulted from the gene suppression of FLS and DFR in grape hyacinth. found that for independent events causing accumulation of red pigments in variegated peach flowers, a particular subset of genes ( C4H, CHS, CHI and F3H) were enhanced and co-regulated in the FBP. The promotion or suppression of any one of the enzymes catalyzing a series of reactions that make up a pathway will change its final product. It is reasonable to expect that the loss or accumulation-of-color adaptations in yams are relatively unconstrained because they can be obtained in various ways, and affected by multiple intracellular factors such as co-pigmentation, pH and metal-chelation in vacuoles. Nevertheless, the complicated mechanism that controls anthocyanin catabolism in different plant species and tissues is far from conclusive. In the past decade, the flavonoid biosynthesis pathway (FBP) has been well characterized genetically and biochemically in model and non-model plants and a number of genes encoding important enzymes and transcription factors responsible for the FBP have been cloned from a dozen organisms such as Arabidopsis, grapevine, Petunia, and maize. Understanding the molecular mechanism of triggering anthocyanin biosynthesis and accumulation in these strains makes it possible to transfer the purple pigment trait to conventional white-flesh cultivar, thus improving the tuber quality and market value. The current study is aimed at understanding how spontaneous variation leads to anthocyanin synthesis in certain yam strains. Therefore, it is no surprise that the purple-flesh yam tubers have recently been selling at a premium price owing to consumer awareness about its health benefits. They have also been shown to have multiple health benefits for humans including immunomodulatory, anticancer, cardio-protective, vasodilation, antithrombotic, and UV-protection due to their antioxidant, and anti-inflammatory properties. Anthocyanins are perhaps the best characterized flavonoids with studies indicating their important role in plant physiology, in particular, plant defense against herbivores and pathogens. Anthocyanins are responsible for the deep purple to red pigmentation of various flowers, fruits, leaves, and other plant tissues. alata tubers have white flesh, but occasionally, purple-flesh tubers with high anthocyanidin content are produced because of spontaneous variation. It is widely cultivated in tropical and subtropical regions. Yam ( Dioscorea alata L.) is an important tuber crop valued for its dietary carbohydrate, amino acids and essential minerals. Finally, 11,793 SSRs were successfully identified with these unigenes and 6,082 SSR markers were developed using Primer 3. The expression of these genes was further confirmed by qRT-PCR. Furthermore, the unigenes encoding chalcone isomerase ( CHS), flavanone 3-hydroxylase ( F3H), flavonoid 3′-monooxygenase ( F3’H), dihydroflavonol 4-reductase ( DFR), leucoanthocyanidin dioxygenase ( LDOX), and flavonol 3-O-glucosyltransferase ( UF3GT) were found to be significantly up-regulated in the DP, implying that these genes were potentially associated with tuber color formation in this elite cultivar. Transcriptome analysis detected 61 unigenes encoding multiple well-known enzymes in the FBP. 511 genes were identified to be more than 2-fold (FDR < 0.05) differentially expressed between the two yam cultivars, of which 288 genes were up-regulated and 223 genes were down-regulated in the DP tubers. These unigenes were further annotated functionally and subject to biochemical pathway analysis. A total of 125,123 unigenes were identified from the DP and DW cDNA libraries, of which about 49.5% (60,020 unigenes) were annotated by BLASTX analysis using the publicly available protein database.
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