Leaf Sheath Substance Metabolism And Relative Research Of Large-panicle Type Rice In Grain Filling Stage

Straw is one of the main agricultural byproducts and has become important forage resources of animal production, which play an important role in the development of Pratacultural science in the world.The investigation was conducted to address the influence of rice straw on grain filling of rice Jinhui 809 cultivar with large panicles and high setting percentage during grain filling by the method of differential proteomics. The aim is to reveal the metabolic mechanism of source-sink-stream in large panicles rice during grain filling period and provide important theoretical references to dig the rice high yield potential, accelerate grain production increase and breeding on grain-straw-dual-use-rice.The results show that a total of 17 protein spots in rice flag leaf had significant expression difference; these proteins were identified using MALDI-TOF/MS analysis and database searching. Among them, twelve were knowen proteins in function. These proteins were involved in substance synthesis and degradation, carbohydrate transportation, plant antioxidation reaction, hormone metabolism, cytoskeleton construction and tissues maturation respectively. The detailed performances are as follows: ribose/galactose/methyl galactoside import ATP-binding protein 1 associated with substance transportation from leaf to grain at grain filling prometaphase, auxin-responsive protein IAA27 responsible for the substance transportation by regulating the activity of ATPase, N-acetyl-glutamate semialdehyde dehydrogenase participating in polyamine metabolism at grain filling terminal phase, and glutathione S-transferase as well as superoxide dismutase playing an important role in plant detoxification and recovery oxygen species damage at late grain filling stage. It concluded that, the photosynthesis assimilation substance of rice leaf was provided to grains powered by ATPase at the prophase and metaphase of grain filling (0 to 14 day), and the regulation function of auxin-responsive protein IAA27 on ATPase was strengthened gradually from prophase to middle-late phase of grain filling (from 0 to 21 days). At the anaphase of grain filling (28 day), the activities of polyamine metabolism was enhanced, besides, the metabolism of antioxidant enzymes and ubiquitin pathway were also strengthended correspondingly, which maintain the regular physiological function of leaf. Thus it could be found, in the later period of rice growth, the function characters of leaves had a complex periodical transformation phenomenon.Twenty-three proteins with obviously different abundances were detected in leaf sheath during grain filling period, and eleven of them were identified in function, which were associated with photosynthesis, hormone regulation, substance transportation, resistance response to plant senescence and cell signal transduction in leaf sheath respectively. The performances are: oxaloacetate decarboxylase alpha subunit, ribulose bisphosphate carboxylase small chain, Rubisco activase and Rubisco binding-protein alpha subunit participating in the photosynthesis of leaf sheath. Auxin response factor (ARF) and geranylgeranyl diphosphate synthase (GGPP synthase) related to hormones metabolism. ADP-ribosylation factor 1 (ARF-1), and vacuolar H~+-ATPase (H~+-ATPase) correlative with substance transportation, metallothionein II -like protein 1A (MT II-1 A) involved in resistant response of leaf sheath, Zinc finger C3HC4 type family protein participating in intracellular signal transduction, and protein kinases playing a role in the regulation of cellular metabolism and signal transduction processes. It concluded that, at the early stage of grain filling, leaf sheath performed the physiological function as sink, which received nutrient substance from leaves. And at the prometaphase of grain filling (0～21 d), leaf sheath also performed the physiological function as source, which produced assimilation substance. In the whole grain filling periods, leaf sheath performed function as flow organs which participated in assimilation products transportation from leaves to grains. Leaf sheathes which connected leaves with grains was the important guarantee of nutrient substance transportation from leaves to grains.In addition, thirty-two proteins with obvious different abundances were detected in grains, and twenty-seven of them were identified in function, which were involved in protein metabolism, carbohydrate and energy metabolism, signal transduction, defence metabolism, gene transcriptional regulation, cell structure forming, and reproduction metabolism. The grains were the main sink organ receiving nutrition substances from leaves and sheathes, in which the nutrition substances were transformed to reserved polysouharide and storage proteins catalyzed by the system of starch and protein synthases, consequently accumulated them to improve the production and quality of rice grains.