Differential Expression and Function Analysis of Proteins in Flag Leaves of Rice During Grain Filling

Abstract

To investigate the molecular mechanism of metabolism in rice ( Oryza sativa L.) source organs, protein expression pattern in flag leaves of rice cultivar Jinhui 809, a cultivar with large panicle and high seed-setting percentage, was analyzed during grain-filling period. Using two-dimensional electrophoresis and mass spectrometry, 17 protein spots with differential expression were detected. Among them, 3 protein spots had the most expression amount from early to medium stage, 9 protein spots for middle–late stages, and 4 protein spots for late stage. In addition, 1 protein spot had two-expression peaks at early and late stages of grain filling. Twelve differential proteins were identified with MALDI-TOF/MS analysis and database searching. They were involved in biosynthesis and degradation, carbohydrate transportation, antioxidation reaction, hormone metabolism, cytoskeleton construction, and tissue maturation. Ribose/galactose/methyl galactoside importing ATP-binding protein 1 participated in photosynthate transportation from leaf to grain in early and medium stages. Auxin-responsive protein IAA27 influenced photosynthate transportation through 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 dismutase played an important role in plant detoxification and fighting against active oxygen damage at late stage of grain filling.