De Novo Transcriptome Analysis to Identify Anthocyanin Biosynthesis Genes Responsible for Tissue-Specific Pigmentation in Zoysiagrass (Zoysia japonica Steud.)

Abstract

Zoysiagrass (Zoysia japonica Steud.) is commonly found in temperate climate regions and widely used for lawns, in part, owing to its uniform green color. However, some zoysiagrass cultivars accumulate red to purple pigments in their spike and stolon tissues, thereby decreasing the aesthetic value. Here we analyzed the anthocyanin contents of two zoysiagrass cultivars ‘Anyang-jungji’ (AJ) and ‘Greenzoa’ (GZ) that produce spikes and stolons with purple and green colors, respectively, and revealed that cyanidin and petunidin were primarily accumulated in the pigmented tissues. In parallel, we performed a de novo transcriptome assembly and identified differentially expressed genes between the two cultivars. We found that two anthocyanin biosynthesis genes encoding anthocyanidin synthase (ANS) and dihydroflavonol 4-reductase (DFR) were preferentially upregulated in the purple AJ spike upon pigmentation. Both ANS and DFR genes were also highly expressed in other zoysiagrass cultivars with purple spikes and stolons, but their expression levels were significantly low in the cultivars with green tissues. We observed that recombinant ZjDFR1 and ZjANS1 proteins successfully catalyze the conversions of dihydroflavonols into leucoanthocyanidins and leucoanthocyanidins into anthocyanidins, respectively. These findings strongly suggest that upregulation of ANS and DFR is responsible for tissue-specific anthocyanin biosynthesis and differential pigmentation in zoysiagrass. The present study also demonstrates the feasibility of a de novo transcriptome analysis to identify the key genes associated with specific traits, even in the absence of reference genome information.

De novo assembly of the Japanese lawngrass (Zoysia japonica Steud.) root transcriptome and identification of candidate unigenes related to early responses under salt stress

“…Figure 3C shows homologies with plants in the family Poaceae. Recent research (Ahn et al, 2015 ) supports our data showing that the most homologous model species to Zoysia is Setaria itallica , followed by Sorghum bicolor and Zea mays . Due to the differences in tissue between cultivar and treatment, our results were not completely consistent with that research.…”

Genome-scale transcriptional study of hybrid effects and regulatory divergence in an F1 hybrid Ruellia (Wild Petunias: Acanthaceae) and its parents

“…6), including two chalcone synthase (CHS), two chalcone isomerase (CHI), two flavanone 3-hydroxylase (F3H), five flavonoid 3'-hydroxylase (F3'H), two flavonoid 3',5'-hydroxylase (F3’5’H), four dihydroflavonol 4-reductase (DFR), four anthocyanidin synthase (ANS) and seven UDP-glucose flavonoid glucosyl transferase (UFGT). Aspects of the above ratios corroborate prior studies that have found comparatively high copy numbers for DFR ( Lotus japonicus [43]; cherries [44]; red leaf lettuce [45]), UFGT (columbines [46]; cherries [44]; Stellera chamaejasme [47]), F3H (peonies [48]), and ANS ( Zoysia [49]). Similarly, our finding of a low copy number for F3'5'H corroborates data from the above studies (one prominent exception is grapevines, which have been found to have exceptionally high copy variants of this enzyme [50]).…”

Sequencing and comparative analyses of the genomes of zoysiagrasses

“… 8 In parallel with the construction of genetic maps, transcriptome analyses have been used to identify abiotic stress-related genes 9 , 10 and genes that control tissue-specific anthocyanin pigmentation in Z. japonica . 11 A complete sequence of the chloroplast genome of Z. matrella L. Merr has also been published. 12 …”