AUTHOR=Jaudal Mauren , Zhang Lulu , Che Chong , Putterill Joanna 

TITLE=Three Medicago MtFUL genes have distinct and overlapping expression patterns during vegetative and reproductive development and 35S:MtFULb accelerates flowering and causes a terminal flower phenotype in Arabidopsis

JOURNAL=Frontiers in Genetics

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2015.00050

DOI=10.3389/fgene.2015.00050

ISSN=1664-8021

ABSTRACT=<p>The timing of the transition to flowering is carefully controlled by plants in order to optimize sexual reproduction and the ensuing production of seeds, grains, and fruits. The genetic networks that regulate floral induction are best characterized in the temperate eudicot <italic>Arabidopsi</italic>s in which the florigen gene <italic>FT</italic> plays a major role in promoting the transition to flowering. Legumes are an important plant group, but less is known about the regulation of their flowering time. In the model legume <italic>Medicago truncatula</italic> (<italic>Medicago</italic>), a temperate annual plant like <italic>Arabidopsis</italic>, flowering is induced by prolonged cold (vernalization) followed by long day lengths (LD). Recent molecular-genetic experiments have revealed that a <italic>FT-like</italic> gene, <italic>MtFTa1</italic>, is a central regulator of flowering time in <italic>Medicago</italic>. Here, we characterize the three <italic>Medicago</italic> FRUITFULL (FUL) MADS transcription factors, MtFULa, MtFULb, and MtFULc using phylogenetic analyses, gene expression profiling through developmental time courses, and functional analyses in transgenic plants. <italic>MtFULa</italic> and <italic>MtFULb</italic> have similarity in sequence and expression profiles under inductive environmental conditions during both vegetative and reproductive development while <italic>MtFULc</italic> is only up regulated in the apex after flowering in LD conditions. Sustained up regulation of <italic>MtFULs</italic> requires functional <italic>MtFTa1</italic> but their transcript levels are not affected during cold treatment. Overexpression of <italic>MtFULa</italic> and <italic>MtFULb</italic> promotes flowering in transgenic <italic>Arabidopsis</italic> plants with an additional terminal flower phenotype on some <italic>35S:MtFULb</italic> plants. An increase in transcript levels of the <italic>MtFULs</italic> was also observed in <italic>Medicago</italic> plants overexpressing <italic>MtFTa1</italic>. Our results suggest that the <italic>MtFULs</italic> are targets of <italic>MtFTa1</italic>. Overall, this work highlights the conserved functions of <italic>FUL-like</italic> genes in promoting flowering and other roles in plant development and thus contributes to our understanding of the genetic control of the flowering process in <italic>Medicago</italic>.</p>