Late-flowering Mutants Co-2 And Ft-1 Vegetative Growth And Phase Changes In Arabidopsis Thaliana

The growth of angiosperms after seed germination mainly experienced two periods:vegetative and reproductive growth, while the vegetative growth period can be divided into the non-reproductive growth contained juvenile phase and the suitable reproductive growth contained adult phase. From juvenile phase to adult phase known as vegetative phase change(Vegetative Phase Change), and from adult phase to reproductive phase known as floral induction (floral induction). Usually accompanied by a series of morphological, physiological and biochemical changes in plants when the phase change starts, for example morphology of the shoot apical meristem, leaf shape, leaf angle, leaf length and width ratio, distribution and density of trichomes, expression changes of abaxial trichomes and internal related gene, these changes reflect the phase change progress during the growth and development of plants.The vegetative growth and reproductive growth are two continuous processes, but the relationship between vegetative phase change and flowering remains unclear.The present study shows that there are five main ways of plants flowering, photoperiod pathway is one of them. In this study, we choose two species of Arabidopsis thaliana related with photoperiod pathway late-flowering mutants co-2 and ft-1, and Ler ecotypes as a control, to research whether reproductive phase change of Arabidopsis thaliana has the effect on vegetative phase change. The main results of this study are as follows:1.Two species of Arabidopsis thaliana related with photoperiod pathway late-flowering mutants co-2 and ft-1, comparied with the wild-type Ler flowering nearly delayed double the time, the total number of rosette leaves were twice than that of the wild-type.2. Abaxial trichomes startd to appeare in the third or the fourth leaf of Ler, while the fifth leaf of co-2 and ft-1. These data showed that vegetative phase change was delayed in late-flowering mutants of co-2 and ft-1.The length/width ratio of rosette leaves and the height/width ratio of shoot apical meristem showed the same trend.3.When applied to different concentrations of exogenous GA4, the flowering time of wild-type and lare-flowering mutants would started earlier with the increase of concentration and at the the highest concentration (30 mg/L), flowering time reached the earliest. However, the late-flowering mutants cannot return to normal condictions even with the GA4 exogenous apllication. At the same time, abaxial trichomes appeared ahead of time, and the same went to the flowering.4. The expression level of miR156 would decrease with the development of the plant. Obviously its expression level decreased during juvenile phase to adult phase transition, consistent with the time of abaxial trichomes appearance, and the expression levels of the three are very high at 10 days, to the expression levels at 15 days,20 days,25 days of all materials showed gradually declining trend. The miR156 expression level of mutant co-2 decreased significantly at 15 days, was 25% of 10 days.5. Expression of SPL3 in SBP-box gene family and miR156 are showing the opposite trend, when reproductive growth phase change is about to occur, the expression quantity of stem tip position of higher. In the juvenile phase (10 d), the expression levels of three species were almost the same,but differences appaered at the vegetative growth phase transition (15 d), Ler had started flowering period at 20 d, but co-2 and ft-1 mutants were still in the adult phase, and the expression levels of SPL3 were slightly lower than that of Ler. The expressionl levels of Ler were fifteen times as the initial level (10 d) when Ler entered the reproductive period (25 d), but the expression levels of SPL3 in two late-flowering mutant were far lower than in Ler.