| Temperature affects plant growth and development and it is an important environmental factor.In natural environment, many plants in the seeding stage will flower early when they experience low temperatures.Tobacco as a research model plant and a cash crop,if they experience low temperatures in the seedling stage(after 10 leaves),they would change in the reactive oxygen species metabolism and the flowering situation,how they change,and when they change,we will study and explore it.Reactive oxygen species as a signaling molecule,whether it has a relationship with the tobacco flower, we will also research it.The results showed that:(1) short-term low temperature(12℃)treatment can make the accumulation of harmful substances MDA 、O2- and H2O2 in tobacco; when the tobacco under low temperature treatment, the role of protective enzyme system were different:the earliest start to play specific role in protective enzymes was SOD,SOD could quickly start in a short time,and then were the CAT and POD.CAT started slightly earlier than POD, CAT mainly had former mid-protective effect, while POD majored protective effect in late. Tobacco in the role of protection mechanisms, H2O2 was gradually being effectively removed and the content from the stress begins to accumulate then gradually decline; O2- content was effectively removed by SOD enzyme and then accumulation phenomenon was also presented.(2) When the tobacco were under low temperature treatment 15d、20d、25d、30d,the early flowering occurred,so when the tobacco in the seeding stage were under low temperature treatment,the low temperature treatment only up to a certain time(greater than 15d) will occur early flowering.When the tobacco were under different low temperature treatment,the budding leaves of tobacco were significantly positively correlated with the content of O2- and H2O2 content,when the content of H2O2 decreased and O2-increased,the number of tobacco leaf reduced,and the tobacco blossomed early.So when the concentration of reaction oxygen species presumably were only at a certain range,it could induce tobacco flowering to some extent.(3)Under spraying exogenous reactive oxygen condition tobacco H2O2 content increased rapidly,O2- content had accumulated in a short time, but the increase was much smaller than H2O2, the accumulation of reactive oxygen species maybe the cause of the accumulation of MDA content. Exogenous action of hydrogen peroxide, the tobacco protective enzyme POD was activated quickly, it played a greater role in the early time; while CAT activity was rapidly activated, but it slightly weaker than the POD enzyme, and then the rate of increase was much greater than the POD enzymes; SOD enzyme responded later than POD and CAT,(4) long-term exogenous H2O2 spraying, tobacco reactive oxygen species in an unbalanced state, especially in the latter part, the relatively high O2- and H2O2 lower tobacco growth and development changed. When exogenous ROS in 5d-25 d by tobacco, tobacco flower development time was in advance, and the number of tobacco with H2O2 content was significantly negatively correlated.(5) low temperature stress and exogenous reactive oxygen experiment results showed that tobacco flower bud differentiation time had different degrees of correlation with tobacco ROS metabolism, so you can speculate on active oxygen metabolism of the tobacco flower development time, but the impact of tobacco flower bud development was not only on a certain level of reactive oxygen species in the absolute amount, the balance may be active oxygen content and a range of concentrations of reactive oxygen species between different regulatory changes have transformed the role of tobacco flower development. |
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