AUTHOR=Chen Kaili , Liu Hongli , Lou Qian , Liu Yali 

TITLE=Ectopic Expression of the Grape Hyacinth (Muscari armeniacum) R2R3-MYB Transcription Factor Gene, MaAN2, Induces Anthocyanin Accumulation in Tobacco

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.00965

DOI=10.3389/fpls.2017.00965

ISSN=1664-462X

ABSTRACT=<p>Anthocyanins are responsible for the different colors of ornamental plants. Grape hyacinth (<italic>Muscari armeniacum</italic>), a monocot plant with bulbous flowers, is popular for its fascinating blue color. In the present study, we functionally characterized an R2R3-MYB transcription factor gene <italic>MaAN2</italic> from <italic>M. armeniacum</italic>. Our results indicated that <italic>MaAN2</italic> participates in controlling anthocyanin biosynthesis. Sequence alignment and phylogenetic analysis suggested that MaAN2 belonged to the R2R3-MYB family AN2 subgroup. The anthocyanin accumulation of grape hyacinth flowers was positively correlated with the expression of <italic>MaAN2</italic>. And the transcriptional expression of <italic>MaAN2</italic> was also consistent with that of <italic>M. armeniacum dihydroflavonol 4-reductase</italic> (<italic>MaDFR</italic>) and <italic>M. armeniacum anthocyanidin synthase</italic> (<italic>MaANS</italic>) in flowers. A dual luciferase transient expression assay indicated that when MaAN2 was co-inflitrated with <italic>Arabidopsis thaliana</italic> TRANSPARENT TESTA8 (AtTT8), it strongly activated the promoters of <italic>MaDFR</italic> and <italic>MaANS</italic>, but not the promoters of <italic>M. armeniacum chalcone synthase</italic> (<italic>MaCHS</italic>), <italic>M. armeniacum chalcone isomerase</italic> (<italic>MaCHI</italic>), and <italic>M. armeniacum flavanone 3-hydroxylase</italic> (<italic>MaF3H</italic>). Bimolecular fluorescence complementation assay confirmed that MaAN2 interacted with AtTT8 <italic>in vivo</italic>. The ectopic expression of <italic>MaAN2</italic> in <italic>Nicotiana tabacum</italic> resulted in obvious red coloration of the leaves and much redder flowers. Almost all anthocyanin biosynthetic genes were remarkably upregulated in the leaves and flowers of the transgenic tobacco, and <italic>NtAn1a</italic> and <italic>NtAn1b</italic> (two basic helix–loop–helix anthocyanin regulatory genes) were highly expressed in the transformed leaves, compared to the empty vector transformants. Collectively, our results suggest that MaAN2 plays a role in anthocyanin biosynthesis.</p>