木薯种茎离体脱水胁迫下生理生化响应研究

Physiology and Biochemistry of Cassava in Response to in Vitro Dehydration Stress

木薯是热带和亚热带地区重要的粮食和经济作物。木薯种茎是目前唯一的繁殖方式,然而采收后木薯种茎如何应对脱水胁迫及糖代谢基因的表达尚不清楚。本研究通过检测对照组和保水处理组的木薯种茎在采后不同时间点水分和糖分的含量变化来探究离体条件下木薯种茎内糖类发挥的作用。通过检测糖类代谢相关基因的表达来解析不同糖分间的代谢关系及离体种茎的活性状态。结果表明,在保水处理组中随着采后时间的延长,种茎中的果糖、葡萄糖和蔗糖的含量先降低后升高,而海藻糖含量变化正好相反。同时,保水处理组的果糖、葡萄糖和蔗糖的含量显著高于对照组,而海藻糖含量显著低于对照组。qPCR分析发现,严重的脱水胁迫显著地提高了糖酵解基因的表达。这些结论表明,脱水胁迫显著影响木薯茎中糖类的相互转化。推测脱水胁迫前20d通过合成海藻糖来响应脱水胁迫,在20~30d则通过分解海藻糖为木薯种茎提供必要的能量物质。同时本研究通过甘油处理提高了木薯种茎的贮藏时间,为木薯种茎的贮藏提供新的方法。

Cassava is an important food and economic crop in tropical and subtropical areas. The cassava stems are currently the only way to reproduce. However, it is not clear how cassava stems respond to dehydration stress and the expression of glucose metabolism genes in cassava after harvest. In this study, the variation of water and sugar content in cassava stems of control and treatment at different time after harvest was investigated respectively to explore the role of sugars in cassava stems in vitro conditions. The metabolic relationship among different sugars and the activity of cassava stem in vitro were analyzed through the expression of genes related to carbohydrate metabolism. The results showed that the contents of fructose, glucose and sucrose in cassava stem decreased firstly and then increased with the prolongation of postharvest time in the treatment, and the contents were significantly higher than those in the control,while the change and content of trehalose was just the opposite. qPCR analysis demonstrated that the expression of glycolytic genes in cassava stem was improved when exposed to severe dehydration stress. The conclusions suggested that the interconversion of sugars in cassava stems was affected significantly exposed to dehydration stress. Thus, it was speculated that trehalose was synthesized in the first 20 days of dehydration stress in response to dehydration stress, and then was decomposed in the second 20-30 days to provide necessary energy substances for cassava stem. In addition, the storage period of cassava stem increased by glycerol treatment, providing a new method for cassava stem storage.