Proteome Analysis Of Nutrient Stress Effects On Rice Ageing During Late Development Stage

Rice is one of the most important staple food crops for human in the world, which plays important role in the agricultural production and scientific research. Besides, it is a model monocot for genome study. Hybrid rice has some merits such as broad adaptability, high resistance, high yield and quality. However, the phenomenon of premature senescence widely appears in the combination of inter-subspecific hybridization, which not only impacts the assimilation and accumulation of dry matter during late growth stage, but also affects the grains filling, dry matter transportation and distribution, hence decreases the potential of high yield. As a very complicated genetic physiological process, premature senescence can be induced by genetic and environmental factors.Hybrid rice Weiyou916was found to be easily induced for premature senescence under nutrient stress. Therefore, classical proteomic approaches including two-dimensional electrophoresis (2-DE), matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF/MS) and bioinformatics technique were used to analyze the differential expression proteomics of roots, leaves, leaf sheathes and grains of Weiyou916. in order to find out the premature senescence mechanism of hybrid rice and metabolism character in different tissues under nutrient stress. It would be the bridge between research prospect and practical application, and it would provide important value in the field of scientific research and agricultural production.The2-DE technology was used to determine the tissue proteome maps of roots, leaves, leaf sheathes and grains of Weiyou916at four different stages, respectively. Totally,121proteins were analyzed by MALDI-TOF/MS and database searching, among which89proteins were identified. The success ratio of proteins identification was73.55%. The identified proteins could be classified into6functional categories. Most of these proteins involved in photosynthesis, resistance, stress signal transportation, and tissue development.The proteins in flag leaves of Weiyou916performed differential expression under nutrient stress at late development stage. Most of these proteins involved in photosynthesis, signal transduction and resistance. The expression amount of proteins associated with photosynthesis such as transketolase, ribulose bisphosphate carboxylase and precursor of ribulose bisphosphate carboxylase main chain were greatly decreased under nutrient stress, which resulted in low photosynthetic rate and low accumulation of dry matter in flag leaves. Lots of proteins involved in signal transduction and resistance such as serine/threonine protein kinases, cysteine synthase and S-adenosylmethionine synthetase in Weiyou916flag leaves were induced and accumulated under nutrient stress, indicating that rice plant could immediately trigger off the resistance system by receptors and signal transduction, and that the great amount of expression on these proteins reduced the damage of stress. Nevertheless, the accumulation of H2O2in flag leaves were induced by high amount of germin-like protein and low amount of catalase, which disturbed the normal physiological activities of leaves.Most of proteins induced by nutrient stress in leaf sheathes were involved in signal transduction and stress resistance, and minority of proteins were related to the photosynthesis. The expression amount of proteins related to signal transduction and stress resistance including ferritin, secretory peroxidases and glutathione S-transferase were decreased under nutrient stress after two weeks, which indicated low resistance, but those enzymes in sheathes under full nutrient supply increased in expression. Vacuolar ATPase and alcohol dehydrogenase involved in stress response increased in protein expression, which showed that leaf sheathes could sense and transfer the environment stress information. The biosynthesis of chlorophyll and photosynthesis proteins in leaf sheathes were inhibited by nutrient stress, hence decreasing photosynthesis of leaf sheathes.Most of protiens with differential expression due to nutrient stress in roots were related to roots growth, development and stress resistance. Proteins involved in growth such as arabinofuranosidase. reversibly glycosylated polypeptide and chitinase have shown drastically increase in response to nutrient stress, which promoted root growth. It could attribute to the fact that roots had a self-regulation mechanism and enhanced the nutrient uptake by increasing the radicular absorption area under insufficient nutrient condition. GPDH. peroxidase and jasmonate-induced lectin were the proteins which associated stress resistance and stress response, and the increase of these proteins indicated that roots had a sensitive-receptor.Finally, nutrient stress resulted in low seed setting rate and1000-grain weight. The analysis of grain proteome by proteomics technology showed that nutrient stress resulted in differential expression in some proteins in grains. Among those proteins, some are associated with grain filling and development, such as glutelin, WD40domain and germin-like protein presented low expression, which resulted in low grain filling rate and germ dysplasia. However, the Hsp70protein, cysteine synthases and chorismate mutase involved in stress resistance and signal transduction showed low expression, which indicated that grains could receive the stress signal and attenuation resistance in plant.In this study, proteome was used to determine the effect of nutrient stress on rice tissues, valuable functional and abundant information of some differential expression proteins was analyzed and acquired. The results would contribute to a deep understanding on the mechanism of early-ageing hybrid rice.