Studies on the relationship between grain sink activity of Japonica/Indica hybrid rice and its grain filling
LI Guo feng,SONG Ping,CAO Xian zu,LIANG Jian sheng,ZHU Qing sen\j(Laboratory of Crop Cultivation and Physiology,Agricultural College of Yangzhou University,Yangzhou,Jiangsu 225009,China)
With two typical Japonica/Indica hybrid rices PC311×Zaoxiandang 18 (poor grain plumpness) and Ce 03×Yangdao4 (good grain plumpness) as materials,the relationship between the grain sink activity and its grain filling was studied.The main results were as follows:(1) The accumulation rate of dry weight or starch of strong or weak potential grains in the intersubspecific hybrid rice (IHR) with good plumpness was higher than that in the IHR with poor plumpness.The filling process of strong and weak potential grains in two IHRs was obviously asychronous.(2) The sucrose content of strong or weak potential grains was higher in early filling stage,and the sucrose content of Ce Yang was clearly higher than that of P Zao.The sucrose content rose again during latter grain development,especially in weak potential grains of P Zao.(3) The activity of sucrose synthase,ADP glucose pyrophosphorylase and starch synthase in endosperm of strong or weak grains in IHR with good plumpness were all higher than those in IHR with poor plumpness,particularly in weak grains.The activity changes of three enzyme were all in accordance with the starch accumulating dynamics.(4) Starch accumulation in amyloplast was promoted by high level of ATP and low level of Pi in endosperm cytoplasm.It was suggested that the grain sink activity played an important role in grain filling.