低温贮藏条件下木薯种茎可溶性糖与干旱胁迫耐受性的相关性研究

    Correlation between soluble sugar and tolerance to drought stress of cassava stem under low temperature storage

    • 摘要:
      目的  研究木薯种茎在不同温度贮藏不同时间后的失水状况、可溶性糖含量以及相关糖代谢信号通路中有关酶基因表达量的变化,分析不同温度下海藻糖含量与种茎失水率的相关性。
      方法  以‘木薯60444’种茎为试验材料,采后分别贮藏于低温(20±2)℃、常温(36±2)℃ 0~30 d,测定种茎失水率、相关可溶性糖含量,运用实时荧光定量PCR分析种茎糖代谢相关基因的表达,木薯种茎海藻糖含量和失水率的相关性分析采用Pearson法。
      结果  低温贮藏组种茎失水率在10、20、30 d显著低于常温贮藏组(P<0.01)。低温与常温贮藏种茎海藻糖含量随贮藏时间的延长整体呈不同程度地提升,且低温贮藏组在10、20、30 d显著低于常温贮藏组(P<0.05);蔗糖、葡萄糖、果糖、麦芽糖含量均随贮藏时间的延长整体呈下降趋势。相关性分析表明,低温贮藏组与常温贮藏组种茎海藻糖含量与种茎失水率呈强线性相关,且2个贮藏组回归方程存在显著差异,低温贮藏组相关系数低于常温贮藏组。实时荧光定量PCR分析表明,低温贮藏不同程度地降低了糖酵解相关基因表达,低温贮藏组海藻糖–6–磷酸合成酶基因(MeTPS-1)的表达量在贮藏10、20、30 d显著低于常温贮藏组(P<0.05)。
      结论  低温贮藏有助于木薯种茎保水,减缓糖酵解速度,延长贮藏时间。海藻糖与木薯种茎失水胁迫呈强相关性,海藻糖含量上升有助于提升木薯种茎的保水能力。

       

      Abstract:
      Objective  The changes of water loss status, soluble sugar content and relative enzyme gene expression in related glyco metabolism signal pathway of cassava stem under different storage temperature and time were studied, and the correlation between trehalose content and water loss rate of cassava stem was analyzed.
      Method  The stem of ‘cassava 60444’ was used as the experimental material. The stem was stored under low temperature of (20±2)℃ and normal temperature of (36±2)℃ for 0–30 d after harvest. The water loss status and soluble sugar content were determined, the change of related enzyme gene expression in the signal pathway of sugar metabolism was analyzed by real-time fluorescence quantification PCR, and the correlation between trehalose content and water loss rate of cassava stem was analyzed by Pearson method.
      Result  The water loss rates of cassava stem in low temperature storage group at 10, 20, 30 d were significantly lower than those in normal temperature storage group (P<0.01). The trehalose contents of cassava stems under low and normal temperature storage overall increased to different degrees with the extension of storage time, and the content of low temperature storage group was significantly lower than that of normal temperature storage group at 10, 20, 30 d (P<0.05). The contents of sucrose, glucose, fructose and maltose in low and normal temperature storage groups all showed a decreasing trend with storage time. Correlation analysis showed that there was a strong linear correlation between trehalose content and water loss rate in low and normal temperature storage groups, and there was significant difference in the regression equations between the two storage groups with the smaller correlation coefficient under low temperature storage. Real-time quantitative PCR analysis showed that the expression of glycolysis related genes increased under low and normal temperature for 10–30 d, most related genes in low temperature storage group had lower expression level, and the expression of trehalose-6-phosphate synthase gene (METPS-1) at 10, 20, 30 d was significantly low than that in normal temperature storage group (P<0.05).
      Conclusion  Low temperature storage of cassava stem contributes to retaining water, slowing down glycolysis rate and prolonging storage time. There is a strong correlation between trehalose and water loss stress of cassava stem, and the increase of trehalose content is helpful to improve the water retention capacity of cassava stem.

       

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