AUTHOR=Xu Dawei , Li Xueou , Wu Xue , Meng Lili , Zou Zhirong , Bao Encai , Bian Zhonghua , Cao Kai 

TITLE=Tomato SlCDF3 Delays Flowering Time by Regulating Different FT-Like Genes Under Long-Day and Short-Day Conditions

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.650068

DOI=10.3389/fpls.2021.650068

ISSN=1664-462X

ABSTRACT=<p>Photoperiod is a crucial inducer of plant flowering. Cycling DOF factors (CDFs) play pivotal roles in the flowering of long-day (LD) and short-day (SD) plants. However, the functions of <italic>CDFs</italic> in the photoperiod regulated flowering remain unclear in day-neutral plants. In the present study, tomato (<italic>Solanum lycopersicum</italic> L. cv. “Ailsa Craig”) seedlings of the wild-type and transgenic lines of overexpressing <italic>CDFs</italic> were treated with different photoperiods. The flowering time and the expression pattern of <italic>SlCDFs</italic> and other <italic>FT-like</italic> genes were investigated. The results showed that tomato <italic>SlCDF1</italic>, <italic>SlCDF2</italic>, <italic>SlCDF3</italic>, <italic>SlCDF4</italic>, and <italic>SlCDF5</italic> are homologs to <italic>Arabidopsis cycling DOF factor 1</italic> (<italic>AtCDF1</italic>). <italic>SlCDF1–5</italic> expression levels were influenced by the developmental stage and the tissue location, and notably, the expression patterns throughout light environments showed two opposite trends. Among the <italic>SlCDF1–5</italic> overexpression transgenic lines, overexpressing <italic>SlCDF3</italic> delayed flowering time in both LD (16 h light/8 h dark) and SD (8 h light/16 h dark) conditions. Furthermore, <italic>SlCDF3</italic> led to an increase in the mRNA level of <italic>SlSP5G</italic>, a tomato <italic>FT-like</italic> gene, in LD conditions, while the transcription level of the other two <italic>FT-like</italic> genes, <italic>SlSP5G2</italic> and <italic>SlSP5G3</italic>, were up-regulated in SD conditions. Taken together, at the transcription level, our results demonstrated that <italic>SlCDF3</italic> played a significant role in controlling tomato flowering under LD and SD conditions, possibly through directly or indirectly regulating <italic>FT-like</italic> genes.</p>