Extensive Transcriptome Changes Underlying the Flower Color Intensity Variation in Paeonia ostii

Abstract

Tree peonies are a group of traditional ornamental plants, especially in East Asia, with Paeonia ostii as one of the most important ancestral species. P. ostii has flowers with varying colors, ranging from nearly white, light pink to deep pink. However, few studies have been done to unravel the molecular mechanisms underlying the flower color intensity variation in plants. Based on comparative analyses of the pigment composition and transcriptomes of P. ostii with different flower color intensities, we found that the anthocyanin concentration was significantly correlated with the flower color intensity in P. ostii. Transcriptome analysis by RNA-Sequencing revealed 7187 genes that were differentially expressed between flowers with different color intensities. Functional enrichment analysis of differentially expressed genes revealed multiple pathways possibly responsible for color intensity variation in P. ostii, including flavonoid biosynthesis, fatty acid oxidation, carbohydrate metabolism, and hormone-mediated signaling. Particularly, while anthocyanin biosynthesis genes showing positive correlations between their expression and anthocyanin concentration in flowers, two transcription factors, PoMYB2 and PoSPL1, seem to negatively regulate anthocyanin accumulation by affecting the activation capacity of the MYB-bHLH-WDR complex, exhibiting an inverse relationship between their expression and anthocyanin accumulation. Our results showed that, although anthocyanin biosynthesis had a direct effect on the pigmentation of the P. ostii flower, other metabolic and hormone-mediated signaling pathways were also contributed to the flower color intensity variation in P. ostii, suggesting complex coordinated changes in the transcriptional network. Differential expression of genes encoding anthocyanin repressors seems to be the major factor responsible for the intensity variation in anthocyanin pigmentation in P. ostii.

Comparative Transcriptomics Provides Insight into Floral Color Polymorphism in a Pleione limprichtii Orchid Population

“…Color changes are related to flower pigment content. To date, the molecular mechanism of flower color transition has been investigated in several species, owing to the main floral pigments having been well characterized in many plants [8][9][10][11][12][13] providing sufficient information for studying floral color formation in non-model species and the opportunity to explore the relationship between phenotypic evolution and color variations.…”

“…Generally, the structural and regulatory genes involved in the ABP have provided a number of targets to reveal the diversity of mutations that could block the ABP [22]. For flower polymorphism within populations, locating the blockage could elucidate the cause of flower color transition at the biochemical and molecular scales [8,10,11]. In addition, understanding their specific ABP is of benefit for predicting evolutionary influences from a genetic perspective.…”

Comparative transcriptome and coexpression network analysis of carpel quantitative variation in Paeonia rockii

“…Then this study is the first attempt to combine two generations of RNA-seq methods to explore the carpel quantitative variation in Paeonia. Compared with the previous reports concerned about tree peonies, we present a higher quality sequencing products [50][51][52][53][54]. For example, more than 60% of the sequence reads are 1000~3500 bp, and the longest ones are over 5000 bp.…”

Phenotypic and seed structural comparison in hybrids of different Brassica rapa and B. oleracea

“…Previous study reported that petal colour is associated with vacuolar pH (Fukada- Tanaka, Inagaki, Yamaguchi, Saito, & Iida, 2000;Yoshida, Kondo, Okazaki, & Katou, 1995), carotenoids (Tanaka, Sasaki, & Ohmiya, 2008;Zhang et al, 2015) and flavonoids (Gao, Yang, Liu, Yang, & Hu, 2016;Rinaldo et al, 2015;Vetten et al, 1999). Flavonoids, especially anthocyanins, as the main pigments in flowers are responsible for colour variations (Jaakola, 2013).…”