Molecular Basis of Natural Variation in Photoperiodic Flowering Responses

• Published in: Developmental cell 2019-07, Vol.50 (1), p.90-101.e3
• Main Authors: Bao, Shengjie, Hua, Changmei, Huang, Gengqing, Cheng, Peng, Gong, Ximing, Shen, Lisha, Yu, Hao
• Format: Article
• Language: English
• Subjects: Arabidopsis; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; cis-regulatory changes; Databases, Genetic; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; florigen; flowering time; Flowers - genetics; Flowers - growth & development; Flowers - metabolism; Gene Expression Regulation, Plant; gibberellin; MYC3; natural variation; Photoperiod; Plants, Genetically Modified - genetics; Plants, Genetically Modified - growth & development; Plants, Genetically Modified - metabolism; Signal Transduction; Trans-Activators - genetics; Trans-Activators - metabolism; transcription factor; Transcription Factors - genetics; Transcription Factors - metabolism
• ISSN: 1534-5807; 1878-1551
• DOI: 10.1016/j.devcel.2019.05.018

Plants exhibit different flowering behaviors in response to variable photoperiods across a wide geographical range. Here, we identify MYC3, a bHLH transcription factor, and its cis-element form the long-sought regulatory module responsible for cis-regulatory changes at the florigen gene FLOWERING LOCUS T (FT) that mediate natural variation in photoperiodic flowering responses in Arabidopsis. MYC3 is stabilized by DELLAs in the gibberellin pathway to suppress FT through binding the ACGGAT motif and antagonizing CONSTANS (CO) activation. Changing photoperiods modulate the relative abundance of MYC3 and CO, thus determining either of them as the predominant regulator for FT expression under different day lengths. Cis-regulatory changes in the MYC3 binding site at FT are associated with natural variation in day-length requirement for flowering in Arabidopsis accessions. Our findings reveal that environmental and developmental signals converge at MYC3 suppression of FT, an elementary event underlying natural variation in photoperiodic flowering responses. [Display omitted] •MYC3 represses flowering through antagonizing CO to regulate FT expression•MYC3 is stabilized by DELLAs in the gibberellin pathway•Changing photoperiods modulate the relative abundance of MYC3 and CO•Natural variation of the MYC3 binding site at FT affects photoperiodic flowering Plants exhibit different flowering behaviors under variable day lengths. Bao et al. demonstrate that day length and the phytohormone gibberellin control flowering time through the regulatory protein MYC3 in Arabidopsis. Changes in the MYC3 binding site at the florigen gene FT contribute to natural variation in day-length requirement for flowering.