Expression Characteristics Of ClFT Gene During Flowering Induced By Photoperiod In Chrysanthemum Lavandulifolium

Chrysanthemum lavandulifolium belongs to the composite family, which is one of the origin of parentage of Chrysanthemum X morifolium, with simple genetic background and is typical short-day plant. This paper isolated FT homologous gene from Chrysanthemum lavandulifolium, and researched on the experssion characteristic of CIFT gene during Chrysanthemum lavandulifolium flowering, in order to explore molecular mechanisms on photoperiod pathway in Chrysanthemum X morifolium flowering, and provide valuable gene resource for molecular breeding in changing of Chrysanthemum X morifolium's flower time. The major results were summarized as follows:1. Cultivation method of Chrysanthemum lavandulifolium in laboratory was developed. A completely randomized block designed experiment demonstrated that the culture result of peat: vermiculite=1:1 was best, which were extremely significantly different between plant height, the number of leaves, stem thickness and root development. The physiological and biochemical index of plants chultured in peat:pearlite= 1:1were better than plants in sand, pearlite:vermiculite= 1:1 and peat:pearlite:vermiculite= 1:1:1, and peat:pearlite= 1:1was also ideal soil-less culture of Chrysanthemum lavandulifolium. Using vermiculite and peat : vermiculite= 1:1 as sowing medium and culture medium, keeping temperature between 20～22℃. illumination is 2500～3500 lx and relative humidity at 30～40%, and giving long-day (14h/10h) maintenance and short-day (12h/12h) treatment when growing Chrysanthemum lavandulifolium in laboratory.2. The precise times of short-day treatment inducing Chrysanthemum lavandulifolium to flower was found. The result showed that after 50 days long-day maintenance of Chrysanthemum lavandulifolium, seedlings with 6 leaves during 30 days short-day treatment had budded in the controlled environment chamber. Paraffin section indicated that seedlings began to flower bud differentiation with 10 days short-day treatment, floret initiated differentiation with 19 days short-day treatment, and the flower bud differentiation were finished with 32 days short-day treatment. The uniformity tissue culture seedlings controled by 9,10, 11,12,13,14h light treatment, which showed that the earlyest budding only need 30 days long day growing and 10days short-day treatment.3. The full-length cDNA of ClFT in Chrysanthemum lavandulifolium was obtained. We designed primers on the base of conservative sequences of knowed FT homologous genes, isolated the full-length cDNA of FT homologous gene from Chrysanthemum lavandulifolium by used RT-PCR and RACE and named ClFT(GenBank number is GU120195). The cDNA was 837bp in length and encoded a protein of 174 amino acid residues, a 302bp 3'-untranslated region and a terminator.And isolated a 212bp length segment of FT homologous genes from Chrysanthemum X morifolium'Lijin'and a 210bp length segment of FT homologous genes Senecio cruentus 'Jester'(GenBank number is GU189418, named ScFT).4. Analysed sequence structure and function of the full-length cDNA of CIFT in Chrysanthemum lavandulifolium. CIFT gene deduced amino acid sequence contains D-P-D-x-P module between 70 and 74 amino acid residue, His at 74 amino acid residue and G-x-H-R module between 116 and 119 amino acid residue, which related to ligand binding site. The homology between deduced amino acid in Chrysanthemum lavandulifolium and other plants was higher than 60%, which was consistent with the biological evolution of paralogous expressed gene in speciation.5. Information of Gene expression patterns of CIFT gene in Chrysanthemum lavandulifolium was preliminarily obtained. CIFT gene expressed in leaves, stems, buds and flowers, not in roots as indicated by semiqualification RT-PCR, and has the highest expression level in stems and buds, next one was leaves, and lowest one was inflorescence. CIFT gene expressed weakly in leaves during long day control, and showed a dramatic increase of expression after short-day treatment. Different short-day treatments leaded to high expression of CIFT gene, but no significant difference. The above results indicated that CIFT gene was closely related to photoperiodic-inductive flowering, and held high expression level in floral induction and flower bud differentiation, which can induce flower in Chrysanthemum lavandulifolium.