Isolation And Function Analysis Of A CONSTANS-LIKE Gene In Medicago Sativa

Alfalfa, with abundent nutrition ,is a kind of important leguminous plants in Temperate Zone and distributes widely in our country. To study the molecular mechanism of flower development and the regulation of flowering time in this species, we isolated a gene MsCOL1(Medicago sativa CONSTANS-LIKE 1 ) from alfalfa, and it was homologous to CO and CO-LIKE genes. Sequence analysis showed that its cDNA was 954 bp in length and encoded a protein of 318 amino acids. The deduced amino acid sequence and clustering analysis revealed that MsCOL1 protein belonged to CO(CONSTANS) family and showed higher identities with PsCOLb in pea, and AtCOL3 in Arabidopsis. Southern blot analysis revealed that MsCOL1 might have two copies in the genome of tetraploid alfalfa. Semi-quantitative RT-PCR analysis showed that MsCOL1 was expressed in roots, stems and leaves. Under short or long day conditions, the transcripts of MsCOL1 demonstrated the rhythmic expression patterns regulated by daylengths. For functional analysis, MsCOL1 gene driven by the CaMV35S promoter was transferred to Arabidopsis. PCR and RT-PCR analysis indicated that the MsCOL1 gene was integrated into the Arabidopsis genome and its expression was detected at transcriptional level. Early flowering occurred in the overexpressed 35S::MsCOL1 plants under both long day and short day conditions, which implied that MsCOL1 was related to the promotion of flowering. In addition, in comparison with wild-type plants, transgenic plants had longer hypocotyls under short day conditions. we also tried to thransformed MsCOL1 into alfalfa. Our studies indicated that MsCOL1 played an important role in regulating flowering time.