GrassTFDB :: Browse Family::Sorghum

Displaying C2C2-CO-like Family from Sorghum


The CO (CONSTANS) gene of Arabidopsis has an important role in the regulation of flowering by photoperiod. CO is part of a gene family with 17 members that are subdivided into three classes termed Group I to III here. All members of the family have a CCT (CO CO-like TOC1) domain near the carboxy terminus. Group I genes which include CO have two zinc finger B-boxes near the amino terminus. Group II genes have one B-box and Group III genes have one B-box and a second diverged zinc finger. Analysis of rice (Oryza sativa) genomic sequence identified 16 genes (OsA-OsP) that were also divided into these three groups showing that their evolution predates monocot/dicot divergence. Eight Group I genes (HvCO1-HvCO8) were isolated from barley (Hordeum vulgare) of which two (HvCO1 and HvCO2) were highly CO like. HvCO3 and its rice counterpart (OsB) had one B-box that was distantly related to Group II genes and was probably derived by internal deletion of a two B-box Group I gene. Sequence homology and comparative mapping showed that HvCO1 was the counterpart of OsA (Hd1) a major determinant of photoperiod sensitivity in rice. Major genes determining photoperiod response have been mapped in barley and wheat (Triticum aestivum) but none corresponded to CO-like genes. Thus selection for variation in photoperiod response has affected different genes in rice and temperate cereals. The peptides of HvCO1 HvCO2 (barley) and Hd1 (rice) show significant structural differences from CO particularly amino acid changes that are predicted to abolish B-box2 function suggesting an evolutionary trend toward a one-B-box structure in the most CO-like cereal genes.

Protein Name
accepted / suggested
Gene Locus Synonym/
Gene Name
Clone in TFome Genome Browser
SbCOL1 Sb01g010420 View in Browser
SbCOL2 Sb04g005250 View in Browser
SbCOL3 Sb04g025660 View in Browser
SbCOL4 Sb04g028920 View in Browser
SbCOL5 Sb04g029480 View in Browser
SbCOL6 Sb06g021480 View in Browser
SbCOL7 Sb10g009480 View in Browser
SbCOL8 Sb10g010050 View in Browser
SbCOL9 Sb10g010860 View in Browser