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

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

doi:10.3389/fpls.2021.650068

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

Front Plant Sci. 2021 May 5:12:650068. doi: 10.3389/fpls.2021.650068. eCollection 2021.

Authors

Dawei Xu^{1

2

3}, Xueou Li³, Xue Wu⁴, Lili Meng⁴, Zhirong Zou^{4

2}, Encai Bao⁴, Zhonghua Bian¹, Kai Cao^{1

4}

Affiliations

¹ Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences, Chengdu, China.
² Horticulture College, Northwest A&F University, Xianyang, China.
³ Department of Plant Science, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China.
⁴ The Agriculture Ministry Key Laboratory of Agricultural Engineering in the Middle and Lower Reaches of Yangtze River, Institute of Agricultural Facilities and Equipment, Jiangsu Academy of Agricultural Sciences, Nanjing, China.

Abstract

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 CDFs in the photoperiod regulated flowering remain unclear in day-neutral plants. In the present study, tomato (Solanum lycopersicum L. cv. "Ailsa Craig") seedlings of the wild-type and transgenic lines of overexpressing CDFs were treated with different photoperiods. The flowering time and the expression pattern of SlCDFs and other FT-like genes were investigated. The results showed that tomato SlCDF1, SlCDF2, SlCDF3, SlCDF4, and SlCDF5 are homologs to Arabidopsis cycling DOF factor 1 (AtCDF1). SlCDF1-5 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 SlCDF1-5 overexpression transgenic lines, overexpressing SlCDF3 delayed flowering time in both LD (16 h light/8 h dark) and SD (8 h light/16 h dark) conditions. Furthermore, SlCDF3 led to an increase in the mRNA level of SlSP5G, a tomato FT-like gene, in LD conditions, while the transcription level of the other two FT-like genes, SlSP5G2 and SlSP5G3, were up-regulated in SD conditions. Taken together, at the transcription level, our results demonstrated that SlCDF3 played a significant role in controlling tomato flowering under LD and SD conditions, possibly through directly or indirectly regulating FT-like genes.

Keywords: FT-like gene; SlCDF3; flowering time; photoperiod; tomato.