2018 ASHS Annual Conference

VvmybA1 is a gene derived from grape (Vitis vinifera) and belongs to the MYB gene family. Our previous study demonstrated that overexpression of VvmybA1 caused accumulation of anthocyanin in leaves of transgenic Ficus lyrata, a popular woody ornamental plant. The purple-leaved F. lyrata was also prone to leaf defoliation in greenhouse. This study was undertaken to analyze molecular mechanisms underpinning the leaf coloration and leaf defoliation. Transcriptome profiling derived from purple-leaved F. lyrata overexpressing VvmybA1 was compared to that of non-transformed, green-leaved plants. The results showed that the accumulation anthocyanin was caused by the upregulation of genes encoding UDP glucose flavonoid 3-O-glucosyl transferase, UDP rhamnose-anthocyanidin-3-glucoside rhamnosyltransferase, chalcone synthase and chalcone isomerase, which are key to anthocyanin biosynthesis. However, genes associated with photosynthesis and energy supply were downregulated. Furthermore, genes involved in defoliation, including beta-glucosidase, shikimate O-hydroxy cinnamoyl transferase and anthocyanidin reductase were all downregulated. The downregulation of these genes may explain why purple leaves are more prone to defoliation. The defoliation is undesirable as F. lyrata has been widely used as a house plant for interiorscaping. This study indicates that overexpression of a particular gene can significantly affect other valuable traits in ornamental plants. Thus, subsequent selection should retain the novel phenotype without compromising other traits.