齐穗至乳熟期不同温度对水稻南粳9108籽粒激素含量、淀粉积累及其合成关键酶活性的影响

Effects of Different Temperature from Full Heading to Milking on Grain Filling Stage on Grain Hormones concentrations, Activities of Enzymes Involved in Starch Synthesis and Accumulation in Rice Nanjing 9108

【目的】为了明确灌浆结实前中期不同温度对晚粳稻籽粒灌浆、总淀粉及其组分含量的影响特征及其机理,【方法】以优质食味粳稻南粳9108为材料,利用植物培养箱控温,于水稻灌浆结实期设置高温(HT,日均温度31℃)、中温(MT,日均温度26℃)和低温(LT,日均温度21℃)三个处理,以自然温度为对照(CK),研究灌浆结实前中期持续高低温对晚粳稻籽粒灌浆、内源激素含量、淀粉及其及合成关键酶活性的影响。【结果】随温度上升(21℃～31℃),晚粳稻结实率和千粒重降低;灌浆前中期籽粒总淀粉积累速率加快,但持续时间短,总含量降低,而直链淀粉含量及其所占比例在整个灌浆期均呈降低趋势;灌浆前中期脱落酸(ABA)含量显著增加,赤霉素(GA3)含量降低,玉米素核苷(ZR)含量呈"先增先降"趋势;MT处理有利于提高灌浆结实期籽粒生长素(IAA)含量,HT和LT处理均降低籽粒IAA含量,LT处理下,IAA含量先降后升,而HT处理籽粒IAA含量一直处于较低水平;籽粒可溶性淀粉合成酶(SSS)活性与ZR变化规律相似,也呈"先增先降"趋势,但二者在灌浆结实期并不同步;淀粉分支酶(SBE)活性增加而淀粉脱分支酶(DBE)活性降低。【结论】不同温度显著影响晚粳稻籽粒内源激素含量和淀粉合成关键酶活性的变化,进而影响晚粳稻籽粒灌浆、总淀粉及其组分的积累。

[Objective]Our aim is to reveal the mechanism of the influence of different temperatures on grain-filling,starch and its components contents of late japonica rice during early-middle grain filling stage.[Methods]With a representative japonica rice cultivar with high quality of Nanjing 9108 as material,high temperature(HT,average daily temperature of 31℃),medium temperature(MT,average daily temperature of 26℃)and low temperature(LT,average daily temperature of 21℃)were set during grain filling in plant incubators at natural temperature as control check(CK).The effects of high and low temperature on grain-filling,hormone contents,and activities of enzymes involved in starch synthesis and accumulation of late japonica rice were studied during early-middle grain filling stage.[Result]With rising temperature(21℃~31℃),the seed setting rate and 1000-grain weight of late japonica rice were on the downward slide.The accumulation of total starch in grain was accelerated with shortened duration and decreased total contents.The amylose content and its proportion followed a decreasing trend during the whole grain filling period.The abscisic acid(ABA)content in grain was significantly increased during the early and middle grain-filling stage.The gibberellin(GA 3)content decreased,and the zeatin riboside(ZR)content firstly increased and then dropped.The content of grain indole-3-acetic acid(IAA)was increased in MT plots during the grain filling stage.The IAA content in grains was reduced in HT and LT plots.The IAA content in the LT plots was decreased firstly and then increased,while in the HT plots,the content was consistently at lower level.The activity of soluble starch synthase(SSS)in grains was equal to that of ZR,which also showed'a increasing-decreasing trajectory',but the SSS and the ZR activities were not synchronized in filling stage.The activity of grain starch branching enzyme(SBE)increased and the activity of grain starch decarboxylase(DBE)decreased.[Conclusion]The changes of grain endogenous hormones and activities of enzymes involved in grain starch synthesis of late japonica rice were significantly influenced by different temperature,as well as the accumulation of starch and its components,grain filling in late japonica rice.