Transcriptome Analysis Identifies Key Candidate Genes Mediating Purple Ovary Coloration in Asiatic Hybrid Lilies

Abstract

Lily tepals have a short lifespan. Once the tepals senesce, the ornamental value of the flower is lost. Some cultivars have attractive purple ovaries and fruits which greatly enhance the ornamental value of Asiatic hybrid lilies. However, little is known about the molecular mechanisms of anthocyanin biosynthesis in Asiatic hybrid lily ovaries. To investigate the transcriptional network that governs purple ovary coloration in Asiatic hybrid lilies, we obtained transcriptome data from green ovaries (S1) and purple ovaries (S2) of Asiatic “Tiny Padhye”. Comparative transcriptome analysis revealed 4228 differentially expressed genes. Differential expression analysis revealed that ten unigenes including four CHS genes, one CHI gene, one F3H gene, one F3′H gene, one DFR gene, one UFGT gene, and one 3RT gene were significantly up-regulated in purple ovaries. One MYB gene, LhMYB12-Lat, was identified as a key transcription factor determining the distribution of anthocyanins in Asiatic hybrid lily ovaries. Further qPCR results showed unigenes related to anthocyanin biosynthesis were highly expressed in purple ovaries of three purple-ovaried Asiatic hybrid lilies at stages 2 and 3, while they showed an extremely low level of expression in ovaries of three green-ovaried Asiatic hybrid lilies during all developmental stages. In addition, shading treatment significantly decreased pigment accumulation by suppressing the expression of several unigenes related to anthocyanin biosynthesis in ovaries of Asiatic “Tiny Padhye”. Lastly, a total of 15,048 Simple Sequence Repeats (SSRs) were identified in 13,710 sequences, and primer pairs for SSRs were designed. The results could further our understanding of the molecular mechanisms of anthocyanin biosynthesis in Asiatic hybrid lily ovaries.

Transcriptome profiling of two contrasting ornamental cabbage (Brassica oleracea var. acephala) lines provides insights into purple and white inner leaf pigmentation

“…This result suggests that the up-regulation of the structural genes of the anthocyanin pathway might responsible for the purple pigmentation in the leaves of purple ornamental cabbage. Similar results were found by Xu et al [ 40 ] for purple pigmentation in the ovary of Asiatic hybrid lilies. Xu et al [ 27 ] reported that the formation of purple bases in the bicolor tepals of the lily cultivar ‘Tiny Padhye’ was due the up-regulation of structural genes of the anthocyanin pathway.…”

Validation of Reference Genes for Quantitative Real-Time PCR during Bicolor Tepal Development in Asiatic Hybrid Lilies (Lilium spp.)

“…Primers for ACT were previously described (Xu et al, 2016). Primer pairs for genes were designed using Primer Premier 5.0 software 1 with the following parameters: melting temperatures (T m ) of 55–65°C, primer lengths of 17–25 bp, and amplicon lengths of 100–300 bp ( Table 1 ).…”

Integrated metabolic profiling and transcriptome analysis of pigment accumulation in diverse petal tissues in the lily cultivar ‘Vivian’

“…These formation mechanisms have also attracted extensive attention in the study of ornamental plants. Additionally, studies on the regulatory gene of flower color in lily have shown that LhMYB12 promotes the coloring of whole petals [25,26]; LhMYB12-lat determines the formation of anthocyanin in ovary [27]; LrMYB15 regulates anthocyanin pigmentation in bud in Lilium regale [28]; and LhMYB18 is involved in the formation of large anthocyanin spots [29]. The lily cultivar 'Vivian', which is an Oriental hybrid lily, is fragrant, brightcolored and is highly desired by consumers.…”