De novo transcriptomic sequencing unraveled the molecular mechanisms of VvMybA1 underlying the alteration of Ficus lyrata leaf color
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VvMybA1 belongs to the MYB gene family. It has been shown that overexpression of VvMybA1 in Ficus lyrata results in accumulation of anthocyanin in leaves along with some side effects, but the underlying mechanisms remain unclear. In the present study, transcriptome of purple-leaved F. lyrata overexpressing VvMybA1 was sequenced and compared with non-modified green-leaved F. lyrata. The results revealed that the accumulation of anthocyanin was caused by the upregulation of the UDP glucose:flavonoid glucosyltrasferase (3GT), UDP rhamnose:anthocyanidin-3-glucoside rhamnosyltransferase (3RT), chalcone synthase (CHS) and chalcone isomerase (CHI), which are key genes for anthocyanin biosynthesis. The genes associated with photosynthesis and energy supply were downregulated, probably resulting in thin and wrinkled leaves. Genes involved in defoliation, including beta-glucosidase, shikimate O-hydroxy cinnamoyl transferase (HCT) and anthocyanidin reductase (ANR) were all downregulated, which might be the reason for the easy defoliation of purple-leaved F. lyrata. Endoglucanase, flavonoids and HCT are important to pathogen resistance. Downregulation of these genes in the present study might explain the high susceptibility of purple-leaved F. lyrata to pathogens. In addition, the downregulation of molecular chaperones might also deteriorate its resistance.
KeywordsAnthocyanin Ficus lyrata Molecular mechanism MYB gene Transcriptome
We thank Dr. Zhijian Li from IFAS in the University of Florida for the comments and corrections of English on the present manuscript. This work was supported by Science and Technology Foundation for Middle-aged and Young Scientist of Fujian Province (JT180142), Science and Technology Innovation Special Fund of Fujian Agriculture and Forestry University (CXZX2017186) and the Key Project from Fujian Provincial Department of Science and Technology (2016I0003).
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