ZmCOL3, a CCT gene represses flowering in maize by interfering with the circadian clock and activating expression of ZmCCT

Abstract

Flowering time is a trait vital to the adaptation of flowering plants to different environments. Here, we report that CCT domain genes play an important role in flowering in maize (Zea mays L.). Among the 53 CCT family genes we identified in maize, 28 were located in flowering time quantitative trait locus regions and 15 were significantly associated with flowering time, based on candidate-gene association mapping analysis. Furthermore, a CCT gene named ZmCOL3 was shown to be a repressor of flowering. Overexpressing ZmCOL3 delayed flowering time by approximately 4 d, in either long-day or short-day conditions. The absence of one cytosine in the ZmCOL3 3'UTR and the presence of a 551 bp fragment in the promoter region are likely the causal polymorphisms contributing to the maize adaptation from tropical to temperate regions. We propose a modified model of the maize photoperiod pathway, wherein ZmCOL3 acts as an inhibitor of flowering either by transactivating transcription of ZmCCT, one of the key genes regulating maize flowering, or by interfering with the circadian clock.

ZmMADS69 functions as a flowering activator through the ZmRap2.7‐ZCN8 regulatory module and contributes to maize flowering time adaptation

“…Maize exhibits tremendous natural diversity in flowering time (Kuleshov, 1933;Buckler et al, 2009). To identify genetic factors controlling the natural variation in flowering time, extensive mapping studies have been conducted using various mapping populations (Austin & Lee, 1996;Ribaut et al, 1996;Salvi et al, 2002;Chardon et al, 2004;Briggs et al, 2007;Buckler et al, 2009;Coles et al, 2010;Hung et al, 2012;Steinhoff et al, 2012;Romay et al, 2013;Yang et al, 2013;Romero Navarro et al, 2017;Jin et al, 2018). The results showed that flowering time in maize is controlled by a complex genetic architecture, with numerous small-effect quantitative trait loci (QTLs) involved .…”

Genome-Wide Identification, Expression Analysis and Functional Study of CCT Gene Family in Medicago truncatula

“…Furthermore, the expressions of several CCT genes in Aegilops tauschii showed obvious circadian rhythmic expression patterns within 24 h [42]. Additionally, ZmCOL3 is a CCT gene that represses flowering in maize by interfering with the circadian clock and activating the expression of another CCT genes ZmCCT [12]. In our study, we found that the expression of 22 MtCCT genes is responsive to circadian rhythm, and most of these genes contained 1-4 light responsive cis-elements in their promoter regions ( Figure 5 and Figure S5).…”

“…It was reported that CCT genes regulate flowering in two main pathways: circadian clock-controlled flowering and photoperiod-regulated flowering [5,12]. Studies on the gene expression of CCT genes in the circadian clock pathway in Arabidopsis are relatively more advanced.…”

dlf1 promotes floral transition by directly activating ZmMADS4 and ZmMADS67 in the maize shoot apex

“…gi1 ( gigantea1 ) is involved in the core oscillator of the maize circadian clock and confers LD‐dependent floral suppression (Bendix et al ., 2013). Three CCT‐domain genes, ZmCOL3 , ZmCCT9 and ZmCCT10 , repress flowering under LD conditions by transducing photoperiod signals (Hung et al ., 2012; Yang et al ., 2013; Huang et al ., 2018; Jin et al ., 2018). ZmMADS1 is a diurnally expressed flowering activator that directly activates ZCN8 expression (Alter et al ., 2016; Guo et al ., 2018).…”