AUTHOR=Han Meixiang , Jin Xuefeng , Yao Wei , Kong Lingjie , Huang Gan , Tao Yujin , Li Lingfei , Wang Xiaojing , Wang Yaqin 

TITLE=A Mini Zinc-Finger Protein (MIF) from Gerbera hybrida Activates the GASA Protein Family Gene, GEG, to Inhibit Ray Petal Elongation

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.01649

DOI=10.3389/fpls.2017.01649

ISSN=1664-462X

ABSTRACT=<p>Petal appearance is an important horticultural trail that is generally used to evaluate the ornamental value of plants. However, knowledge of the molecular regulation of petal growth is mostly derived from analyses of <italic>Arabidopsis thaliana</italic>, and relatively little is known about this process in ornamental plants. Previously, <italic>GEG</italic> (<italic>Gerbera hybrida</italic> homolog of the gibberellin [GA]–stimulated transcript 1 [<italic>GAST1</italic>] from tomato), a gene from the GA stimulated Arabidopsis (GASA) family, was reported to be an inhibitor of ray petal growth in the ornamental species, <italic>G. hybrida</italic>. To explore the molecular regulatory mechanism of <italic>GEG</italic> in petal growth inhibition, a mini zinc-finger protein (MIF) was identified using yeast one-hybrid (Y1H) screen. The direct binding of <italic>GhMIF</italic> to the <italic>GEG</italic> promoter was verified by using an electrophoretic mobility shift assay and a dual-luciferase assay. A yeast two-hybrid (Y2H) revealed that GhMIF acts as a transcriptional activator. Transient transformation assay indicated that <italic>GhMIF</italic> is involved in inhibiting ray petal elongation by activating the expression of <italic>GEG</italic>. Spatiotemporal expression analyses and hormone treatment assay showed that the expression of <italic>GhMIF</italic> and <italic>GEG</italic> is coordinated during petal development. Taken together, these results suggest that <italic>GhMIF</italic> acts as a direct transcriptional activator of <italic>GEG</italic>, a gene from the GASA protein family to regulate the petal elongation.</p>