Effect of T-FACE high temperature on genes expression level of key enzymes involved in starch metabolism in superior spikelets and inferior spikelets of rice during grain filling period
[Objectives] This study investigated how the simulation of the global warming could affect the genes expression level of key enzymes involved in starch metabolism during grain filling of rice and provided a theoretical basis for response to the global warming. [Methods] The large-panicle japonica rice strain(CJ03)and the middle-panicle japonica rice variety('Ningjing 3')were used as materials and T-FACE(Temperature Free-air Controlled Enhancement)high temperature treatment was performed at heading stage. The thousand grain weight,grain filling rate,the content of total starch and amylose,as well as expression level of genes involved in starch metabolism at 10 and 20 days post anthesis in rice superior spikelets(SS)and inferior spikelets(IS)were measured. [Results] In the early stage of rice grain filling,compared with the control IS,under the treatment of T-FACE high temperature,the grain filling process of IS was significantly promoted,which was mainly manifested in the increased filling rate and its peak value,as well as the advanced filling initiation of IS. While in the late grain filling stage,with the prolonged treating time,the grain filling active periods of SS and IS were shortened. The results of real-time PCR showed that the key enzymes which involved in starch metabolism,such as sucrose synthase(SuSase),ADP-glucose pyrophosphorylase(AGPase),soluble starch synthase(SSS),granule-bound starch synthase(GBSS)and starch branching enzyme(SBE),and their gene expression levels were various among the different treatments and the different parts in the same panicle. At 10 days post anthesis,under the T-FACE high temperature treatment,the expression levels of genes which were related to the synthesis of SuSase,AGPase,SSS and SBE were up-regulated,while the situation was opposite in GBSS. At 20 days post anthesis,compared with SS,the expression levels of genes which were related to the key enzymes involved in starch metabolism were down-regulated siginificantly in the IS under the different treatments. [Conclusions] The filling rate of IS was increased under the T-FACE high temperature treatment,mainly due to the up-regulation of genes expression levels which were related to the key enzymes involved in starch metabolism.