Function Of AP1CHL Gene From Chloranthus Spicatus

Flowering is an important stage in the transition from vegetative growth to reproductive growth in the lives of plants. The differentiation and development of floral organs have been the focus of biologists' study, not only for the variety of floral shape and other characteristics, but also for its important economic value.Two classes of genes control the development of flower: flower meristem identity genes which promote the initiation of flower meristem from inflorescence meristem, and the floral organ identity genes which, also named homeotic genes, determine which kind of floral organs will initiate. The flower meristem identity genes can activate the homeotic genes to some extent.MADS-box genes family plays a key role in the molecular regulation of floral development, and most of them in plants belong to the typeII class, that is, the gene sequence is composed of M, I, K and C domains. The M domain, which encodes the DNA-binding domain and plays the roles of both binding DNA and forming dimmers, is the most conserved region. According to the classical "ABC" model, three classes of genes act to specify floral organs, namely sepals (A only), petals (A+B), stamens (B+C), or carpels (C only). Later, some new found MADS-box genes result in the "ABCD" model, "ABCDE" model and "quartet" model. All of these models make the understanding of floral development deeply.Chloranthus spicatus belongs to Chloranthaceae Chloranthus according to its phylogenic position. It has no perianth and is one of the oldest angiosperm that have fossil. In the classification of angiosperm, the simplism of floral organ is thought to be a derivative identity. But some new data about fossil show that the small and simple flowers appeared before the complicated flowers, like the flower of Chloranthus spicatus. Thus Chloranthus spicatus' special morphological characteristics and position in the plant phylogenic tree plays a great role in the research of the origin of perianth and flowers.APJCHL gene is cloned from Chloranthus spicatus. Blast and Phylogenetic analysis show that it belongs to MADS-box gene family and may take the A class function. By a serial steps of endonuclease digestions and ligations, sense, partial antisense and full antisense expression vectors were constructed and the gene sequence was promoted by CaMV35S promoter. Transgenic tobaccos have been obtained by antibiotic screening and PCR screening after the transformation mediated by Agrobacterial. The positive tobaccos were planted in greenhouse. Southern blotting of transgenic tobacco is carrying out. Arabidopsis (Columbia ecotype) was transformed by floral dip method mediated by Agrobacterial and TO seeds have been harvested. The antibiotic screening of positive Arabidopsis plant is carrying out now.The morphology of flowers of transgenic tobaccos has some changes in the number of sepals, petals and stamens of antisense tobaccos. This shows that the APJCHL gene perhaps takes part in the determination of primodia identity of sepals, petals and stamens. The results mentioned above are in accord with the functions of A class genes -- not onlydetermining the floral meristem identity but also determining the floral organ identity.