中文摘要：

【目的】分析低温诱导下朵丽蝶兰（Doritaenopsis hybrid）叶片的营养生长特性以及碳水化合物的含量与相关基因表达模式的变化规律,为明确低温对朵丽蝶兰花梗抽出的生理生化机制奠定基础。【方法】对朵丽蝶兰进行高温（30℃/25℃）和低温（22℃/18℃）处理,测定其叶片的生长和叶绿素荧光,以及碳水化合物含量的变化,同时对朵丽蝶兰＂温敏＂SSH文库中分离的两个糖转运蛋白基因（片段）在相对低温处理下的表达特性进行分析。【结果】经过22℃/18℃（昼/夜）的低温处理29—36 d,98%的植株抽出花梗,并在以后的培养中（3个月）陆续开花。而高温对照组无植株开花。整个低温处理阶段中,朵丽蝶兰叶面积的增长显著低于高温处理,并且在低温处理的前4周（28 d）,叶片的光能转化效率和PSII活性明显下降,叶片淀粉含量急剧下降,还原糖含量持续增加,蔗糖含量在第28天前后表现为先增后减,其中,在低温处理21—35 d中,DhST1的mRNA表达与蔗糖含量的变化一致,而DhSUT1则表现为持续下降,但二者在抽出的花梗中都有较高的表达量。【结论】低温能够明显减缓朵丽蝶兰叶片的营养生长,在处理的开始阶段对光合系统产生一定抑制作用,调节碳水化合物的降解与累积,同时协调糖转运相关蛋白基因的表达,成为推动朵丽蝶兰顺利转向生殖生长并抽出花梗的动力之一。

英文摘要：

【Objective】Experiments were performed to understand the response of the vegetative growth and the expression patterns of related genes to low temperature,which is important to approach the mechanism of flower differentiation and its temperature-sensitive mode and,hence,to accelerate the industry of Doritaenopsis hybrid.【Method】A Doritaenopsis hybrid ＇Tinny Tender＇（Doritaenopsis Happy smile ×Happy valentine） was incubated at 22℃/18℃（day/night）,with 30℃/25℃ as control,to induce the floral transition.Changes of the contents of starch,sucrose and reducing sugar,leaf area,ratios of Fv/Fm and Fv/Fo,and mRNA transcripts of 2 genes isolated from the suppression subtractive hybridization（SSH） library of ＇Tinny Tender＇（DhSUT1,a sucrose transporter and DhST1,a sugar transporter） were investigated.【Result】Comparing with the control,slower increase of the leaf area and reduction of Fv/Fm and Fv/F0 were observed under 22℃/18℃ for 28 d.The peduncles sprout in most plants under 22℃/18℃ for about 29-36 days,and after 3 months,98% of plants flowered.Quick degradation of starch,continuous accumulation of reducing sugar and increase of sucrose to peak at 28 d were determined.The mRNA transcripts of DhST1 rose up to the peak at 28 d in cold-inducing,while those of DhSUT1 were decreased.【Conclusion】These results indicated that during cold-induced floral initiation,vegetative growth and photosynthesis capacity of Doritaenopsis hybrid were slow down,and sharp changes in carbohydrates were consist with up-regulated of DhST1 and down-regulated of DhSUT1 expression,suggesting those responses to low temperature and performance of candidate genes were related to the unique flowering induction of Doritaenopsis.