Differential Expression and Function Analysis of Proteins in Flag Leaves of Rice during Grain-Filling Period

Abstract

The experiment was conducted to study the protein expression pattern in flag leaves of rice cultivar Jinhui 809 with large panicles and high grain-setting percentage during grain-filling period using two-dimensional electrophoresis and mass spec-trometry.The results showed that there were 17 protein spots with differential expression.Among them,three protein spots had the most expression amount from early to mid-stage,nine protein spots had the most expression amount from middle to late stages,four protein spots reached the most expression amount in late stage,and one protein spot had two top expression peaks in early and late stages of grain filling,respectively.MALDI-TOF/MS analysis and database searching identified 12 differential proteins involved in biosynthesis and degradation,carbohydrate transportation,anti-oxidation reaction,hormone metabolism,cytoskeleton construction and tissue maturation,respectively.Ribose/galactose/methyl galactoside importing ATP-binding protein 1 was par-ticipated in photosynthates transportation from leaf to grain in early and mid-stages.Auxin-responsive protein IAA27 influenced photosynthates transportation by regulating the activity of ATPase.N-acetyl-glutamate semialdehyde dehydrogenase delayed leaf senescence through regulating polyamine metabolism in late stage.In addition,glutathione S-transferase and superoxide dismu-tase played an important role in plant detoxification and fighting against oxygen species damage at late stage of grain filling.The current results provide the valuable evidences for us to reveal the metabolism mechanism at grain filling stage in super-rice.