Effect Of Jarovization On Physiological Properties Of Flowering Cabbage Bolting And Related Genetic Expression

Flowering Chinese cabbage (Brassica rapa syn. campestris L. ssp. Chinensis var.utilis Tsen et Lee), originated from south of China, is possesses the large cultivated area insouth of China. Produced organ of flowering cabbage is flower sedge, development offlowering cabbage’s bolting doesn’t require low temperature, even without induction oflow temperature, its bolting can be finished normally, mechanism of flowering cabbage’sbolting is different from that of brassicaceous vegetable such as chinese cabbage andcabbage(their early bolting is induced by low temperature). Howerer, induction of lowtemperature can promote development of flowering cabbage, thus can promote theirbolting and flowering at early stage, there is no related study report in this approchcurrently.Early-maturing variety of flowering cabbage ‘bilvcutai’ and ‘cuilv80’ were taken astest materials, firstly, under different days of low temperature treatment(15，20，25，30d),change rules of physical signs including soluble protein of flowering cabbage,malonaldehyde(MDA), superoxide dismutase(SOD) were compared. Fragments ofrelated genes for flowering cabbage’s bolting were obtained by method of homologoussequence’s cloning, effect of different vernalization time on expression features of relatedgenes for flowering cabbage’s bolting were studied by using semiquantitative RT-PCRtechnology. Full-length sequence of flowering cabbage’s histoneacetyltransferase(BrcuHAC1) was amplified by RT-PCR technology, and spatio-temporalexpression features of these genes were analyzed. The resuits were as follows:(1) With the increased low temperature treatment time, soluble protein content offlowering cabbage leaves reduced, activity of SOD increased firstly and then decreased,when the low temperature treatment time was15d, activity of SOD was the strongest.Variation trend of MDA content was opposite to SOD, when the low temperature treatmenttime was15d, MDA content was the lowest.(2) BrcuFLC and BrcuFRI gene were obtained, fragment size were612bp and463bprespectively, expression order of BrcuFLC in different organs was leaf>stem>flower>root, for BrcuFRI, the order was root>stem>flower>leaf. Low temperature treatmentobviously inhibited expression of BrcuFLC, inhibiting effect was increased byincreasement of low temperature treatment time. Expression quantity of BrcuFRI underdifferent days of low temperature treatment(0，15，20，25) was shown to be a increasingtrend with the development of first, second，third，forth，fifth piece of euphylla stage andbolting stage. For30days’ low temperature treatment, expression quantity was shown to bea declining trend.(3)Three independent flowering genes of flowering cabbage were obtained, namedBrcuFCA, BrcuFVE and BrcuFLD respectively, fragment size were1001bp,238bp and 774bp respectively. expression quantity of three genes in flower organs were the most.During the different stages of low temperature treatment, expression quantity ofindependent flowering genes was shown to be a increasing trend.(4) Amplification result of BrcuFT(downstream gene of BrcuFLC) fragment size was249bp, expression level under different treatments shown to be a increasing trend with thedevelopment of first, second，third，forth，fifth piece of euphylla stage and bolting stage,moreover, expression quantity of this gene in flower organ was the most.(5) Fragment size of histone acetyltransferase gene BrcuHAC1of flowering cabbagewas804bp, the similarity to the arabidopsis homologous gene was95%. Spatio-temporalexpression characteristic analysis showed that genetic expression of this gene wasincreased with formation process of flowering cabbage bud, expression quantity of boltingstage was the most. Meanwhile, expression were also found in roots, stems, flowers, leaves,expression quantity in flower organs was the most, these indicated that target gene wasrelated to development of flowers.In conclusion, flowering cabbage’s bolting and flowering are mainly by independentflowering, howerer, low temperature treatment may affects expression of related genes forflowering cabbage’s bolting at different levels. It can indicate that development offlowering cabbage may effected by low temperature induction.