Expression of sucrose synthase genes involved in enhanced elongation of pondweed (Potamogeton distinctus) turions under anoxia
Expression of sucrose synthase genes involved in enhanced elongation of pondweed (Potamogeton distinctus) turions under anoxia
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DOI：
10.1093/aob/mci220
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发表时间：
2005-09-01
期刊：
影响因子：
4.2
通讯作者：
Ishizawa, K
中科院分区：
文献类型：
--
作者：
Harada, T;Satoh, S;Ishizawa, K
背景与目的单子叶水生池塘草（Potamogeton distinctus）的越冬芽（turions）对缺氧胁迫具有高度的耐受性。在海藻的厌氧伸长过程中，蔗糖代谢伴随着蔗糖合酶（SuSy）活性的增强而活跃运作。本研究的目的是分离SuSy基因，并研究其在缺氧和其他刺激下的转录变化。方法采用PCR方法从沼液藻囊中分离SuSy基因，检测SuSy基因在缺氧、糖和植物激素条件下的转录水平。此外，我们还研究了缺氧对可溶性部分和微粒体部分SuSy活性的影响。关键结果从池塘草中克隆了两个SuSy基因PdSUS1和PdSUS2的cdna。缺氧条件下PdSUS1转录本水平升高，但糖处理没有。2,4-二氯苯氧乙酸（2,4- d）进一步增强了缺氧刺激下的turon伸长，山梨醇、2-脱氧葡萄糖（2- dglc）和脱落酸（ABA）抑制了缺氧刺激下的turon伸长。在缺氧条件下，PdSUS1转录本水平增加2,4- d，山梨醇降低。PdSUS2转录本水平不受缺氧和任何其他处理的显著影响。在缺氧条件下，可溶性部分的酶活性增强，微粒体部分的酶活性没有增强。结论缺氧条件下PdSUS1转录上调可能与缺氧条件下糖饥饿无关。在缺氧条件下，2,4- d和山梨醇处理的水稻茎秆伸长与PdSUS1转录本水平呈正相关。细胞质中SuSy活性的增加可能有助于糖代谢和维持缺氧条件下的茎伸长。
Background and Aims Overwintering buds (turions) of the monocot aquatic pondweed species (Potamogeton distinctus) are highly tolerant to anoxic stress. Sucrose metabolism accompanied by enhanced activity of sucrose synthase (SuSy) operates actively during anaerobic elongation of pondweed turions. The aim of this study is to isolate SuSy genes from the turions and to investigate their transcriptional changes in response to anoxia and other stimuli.Methods SuSy genes were isolated from pondweed turions by PCR methods and transcript levels of SuSy genes were examined in response to anoxia, sugars and plant hormones. In addition, the effects of anoxia on SuSy activity were examined both in the soluble fraction and in the microsomal fraction.Key Results cDNAs of two SuSy genes (PdSUS1 and PdSUS2) were cloned from pondweed turions. The levels of PdSUS1 transcripts increased under anoxia but did not with sugar treatments. Anoxia-stimulated elongation of turions was further enhanced by 2,4-dichlorophenoxyacetic acid (2,4-D) and suppressed by treatments with sorbitol, 2-deoxyglucose (2-dGlc) and abscisic acid (ABA). The levels of PdSUS1 transcripts were increased by 2,4-D and decreased by sorbitol under anoxia. The levels of PdSUS2 transcripts were not significantly affected by anoxia and any other treatments. SuSy activity of turions under anoxia was enhanced in the soluble fraction, but not in the microsomal fraction.Conclusions Up-regulation of PdSUS1 transcription under anoxia may not be attributed to sugar starvation under anoxia. A positive correlation between stem elongation and the level of PdSUS1 transcripts was observed in turions treated with anoxic conditions, 2,4-D and sorbitol. The increase in SuSy activity in the cytosol may contribute to sugar metabolism and sustain stem elongation under anoxia.