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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Plant Sci. | doi: 10.3389/fpls.2019.01218

Homologs of LEAFY and UNUSUAL FLORAL ORGANS promote the transition from inflorescence to floral meristem identity in the cymose Aquilegia coerulea.

  • 1California State Polytechnic University, Pomona, United States
  • 2Ecology and Evolutionary Biology, College of Agriculture and Life Sciences, Cornell University, United States
  • 3Department of Organismic and Evolutionary Biology, Faculty of Arts and Sciences, Harvard University, United States
  • 4Organismic and Evolutionary Biology, Harvard University, United States

Homologs of the transcription factor LEAFY (LFY) and the F-box family member UNUSUAL FLORAL ORGANS (UFO) have been found to promote floral meristem identity across diverse dicot model systems. The lower eudicot model Aquilegia produces cymose inflorescences that are independently evolved from the well-studied cymose models Petunia and tomato. We have previously characterized the expression pattern of the Aquilegia homolog AqLFY but in the current study, we add expression data on the two UFO homologs, AqUFO1 and 2, and conduct virus-induced gene silencing of all the loci. Down-regulation of AqLFY or AqUFO1 and 2 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 AqUFO1/2 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 AqLFY or AqUFO1/2 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.

Keywords: Aquilegia, Inflorescence structure, floral meristem identity, LEAFY (LFY), UNUSUAL FLORAL ORGANS

Received: 18 Jun 2019; Accepted: 04 Sep 2019.

Copyright: © 2019 Sharma, Meaders, Wolfe, Holappa, Walcher-Chevillet and Kramer. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Bharti Sharma, California State Polytechnic University, Pomona, Pomona, 91768, California, United States, bsharma@cpp.edu