Analysis Of Factors Correlated With Early-flowering Induced By Low Temperature In Tobacco

The tobacco (Nicotiana tabacum .vc. K326) plants were cultured in 4℃for 24h,the another treatment is that only one leaf was exposed in 4℃condition, Activities of carbohydrate metabolism key enzyme,and related gene expression level, SUT1 gene expression level, H2O2 contents and the redox state of ascorbate pool were analyzed in different tissues,in order to study regulating factor in early-flowering induced by low temperature in tobacco. In the validating period,supplement with sucrose,ascorbate acid and DHA in tobacco bud, SOC1 gene expression levels were detected,their functions in flowering process.The main results are as follows:1.Low temperature stimulates sucrose transport faster to apical meristem. Synthesis,content and transportation of sucrose were studied by the numbers,and starch coloration showed the distribution of it in different area of leaf. The results showed that:after low temperature treating,soluble sugar content increase,enzyme and genes correlated with sucrose,activity of SPS increase,amylase was depressed,and starch in lateral veins was increased,SPSC gene was up-regulated,and the same is SUT1 gene in leaves, transport of sucrose from leaf to apical meristem is increased.The increasing number is 60. 22% and 16.55% in two treatments, this change is due to up-regulation of SPSC and SUT1,not to starch.2.Low temperature induces ascorbate pool going to oxidation state.after treating,the content of ascorbate acid decreased in leaf,and there were no obvious change in petiole, stem and apical meristem,but the tontent of DHA is escalating,the increase from petiole to apical meristem are 3.09%,25.05%,22.45%in whole treatment, 16.15%,5.81%,19.73%in one leaf treatment.showed that low temperature increased the content of DHA,ascorbate acid go to oxidation state in bud.3.Low temperature up-regulate gene about flowering. The results showed that after treat tobacco with low temperature,SOC1 gene expression increase distinctly,one leaf treatment have the same result with whole treatment.4.Effects of factors on gene expression of flowering.Low temperature stimulates sucrose and DHA increase ,SOC1 gene express in apical meristem, The bud of K326 treated by sucrose, ascorbate acid and DHA,and then detect the expression of SOC1 gene.The results showed that: DHA up-regulate the expression of SOC1 clearly in bud, sucrose and ascorbate acid has no direct regulation to it, indicating DHA is important factor in early-flowering induced by low temperature in tobacco.