AUTHOR=Sharma Bharti , Meaders Clara , Wolfe Damien , Holappa Lynn , Walcher-Chevillet Cristina , Kramer Elena M. 

TITLE=Homologs of LEAFY and UNUSUAL FLORAL ORGANS Promote the Transition From Inflorescence to Floral Meristem Identity in the Cymose Aquilegia coerulea

JOURNAL=Frontiers in Plant Science

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2019.01218

DOI=10.3389/fpls.2019.01218

ISSN=1664-462X

ABSTRACT=<p>Homologs of the transcription factor <italic>LEAFY</italic> (<italic>LFY</italic>) and the F-box family member <italic>UNUSUAL FLORAL ORGANS</italic> (<italic>UFO</italic>) have been found to promote floral meristem identity across diverse dicot model systems. The lower eudicot model <italic>Aquilegia</italic> produces cymose inflorescences that are independently evolved from the well-studied cymose models <italic>Petunia</italic> and tomato. We have previously characterized the expression pattern of the <italic>Aquilegia</italic> homolog <italic>AqLFY</italic> but in the current study, we add expression data on the two <italic>UFO</italic> homologs, <italic>AqUFO1</italic> and <italic>2</italic>, and conduct virus-induced gene silencing of all the loci. Down-regulation of <italic>AqLFY</italic> or <italic>AqUFO1</italic> and <italic>2</italic> does not eliminate floral meristem identity but, instead, causes the transition from inflorescence to floral identity to become gradual rather than discrete. Inflorescences in down-regulated plants generate several nodes of bract/sepal chimeras and, once floral development does commence, flowers initiate several whorls of sepals before finally producing the wildtype floral whorls. In addition, silencing of <italic>AqUFO1/2</italic> appears to specifically impact petal identity and/or the initiation of petal and stamen whorls. In general, however, there is no evidence for an essential role of <italic>AqLFY</italic> or <italic>AqUFO1/2</italic> in transcriptional activation of the B or C gene homologs. These findings highlight differences between deeply divergent dicot lineages in the functional conservation of the floral meristem identity program.</p>