Changes of structure and functional properties of rice protein in the fresh edible rice during the seed development

It has been reported that fresh edible rice has more bioactive compounds and its protein is easier to digest and has lower hypoallergenic than mature rice. In this paper, the changes in structure and functional properties of proteins at five different stages, including early milky stage(EMS), middle milky stage(MMS), late milky stage(LMS), waxy ripe stage(WS)and ripening stage(RS), during the seed development were investigated. It was found that with the seed developing, the molecular weight of fresh rice protein gradually become larger while the secondary structure changed from the highest content of disordered structure at MMS to the highest content of ordered structure at RS, which affect the surface hydrophobicity and then the functional properties of proteins, including foaming properties, emulsifying properties and oil holding capacity. Fresh rice protein at MMS has the strongest surface hydrophobicity while fresh edible rice protein at RS has the strongest oil holding capability. The results of our study can provide a theoretical basis for the application of fresh rice protein in the food industry and help to develop new fresh edible rice food.

Comparative Study of the Protein Contents of Local and Imported Rice Consumed in Senegal

Protein is essential for the growth and maintenance of the body. They play a crucial role in different biological processes. This study focuses on comparing the protein contents of local rice grown in the Senegal River valley and rice imported from Asia. The objective is to evaluate the importance of the protein nutritional value of local rice compared to imported rice. Protein contents were determined using the Kjeldahl method. The results of the protein assays show that local rice varieties such as Sahel 108 and Sahel 134 grown in the Thilène basins had protein percentages comparable to those of imported rice. The protein percentages were 15.19% ± 0.91% for the Sahel 108 variety and 16.62% ± 0.01% for the Sahel 134 variety compared to 15.8% ± 0.01% on average for imported rice. Thus from the point of view of protein content, local rice has a nutritional value identical to that of imported rice which it can validly replace. It is important in Senegal to encourage local production, which would make it possible to reduce imports on the one hand and to make quality rice available to the local Senegalese market on the other. Sahel varieties with high protein contents deserve large-scale development to meet the country’s protein needs.

Rice Storage Proteins:Focus on Composition,Distribution,Genetic Improvement and Effects on Rice Quality

Rice storage proteins(RSPs)are plant proteins with high nutritional quality.As the second largest type of storage substance in rice,it is the main source of protein intake for people who consume rice as a staple food.The content and type of RSPs affect the appearance,processing quality and eating quality of rice.These effects involve the distribution of RSPs in rice grains as well as the interactions of RSPs with other components such as starch in rice grains.In the past two decades,some progress has been made in the genetic improvement of RSPs.However,the determination mechanism of protein content and composition in rice is still unclear,and the mechanism of the effect of RSPs on rice quality has not been elucidated.In this review,the composition,biosynthesis and distribution of RSPs,and quantitative trait loci mapping and cloning of RSP genes are summarized,the research progress of the influence of RSPs and their components on rice quality are reviewed,and the research directions in the future are proposed.

LHD3 Encoding a J-Domain Protein Controls Heading Date in Rice

Heading date is one of the most important agronomic traits of rice,which critically affects rice ecogeographical adaptation,yield and quality.In this study,a late heading date 3(lhd3)mutant was screened from the^(60)Co-γirradiation mutant library.The lhd3 delayed heading date in rice under both short day and long day conditions.Map-based cloning combined with Mutmap strategy was adopted to isolate the causal LHD3 gene.The LHD3 gene encodes a DNA_J domain protein,which was ubiquitously expressed in various plant organs,and dominant expressed in stems and leaves.Subcellular localization analysis showed that LHD3 was localized to nucleus,indicating that LHD3 may interact with other elements to regulate the expression of flowering genes.The transcriptions of the heading activators Ehd1,Hd3a and RFT1 significantly decreased in the lhd3 mutant,suggesting that LHD3 may control the heading date through the Ehd1-Hd3a/RFT1 photoperiodic flowering pathway.The variation and haplotype analyses of the genomic region of LHD3 showed that there were 7 haplotypes in the LHD3 region from 4702 accessions.The haplotypes of LHD3 can be divided into two classes:class a and class b,and the heading dates of these two classes were significantly different.Further study showed that two single nucleotide polymorphisms(SNPs),SNP10(G2100C)in Hap II and SNP3(C861T)in Hap VII,may be the functional sites causing early and late heading in accessions.Nucleotide diversity analysis showed LHD3 had been selected in the indica population,rather than in the japonica population.Therefore,the present study sheds light on the regulation of LHD3 on heading date in rice and suggests that LHD3 is a novel promising new target for rice molecular design and breeding improvement.

Water relations and an expression analysis of plasma membrane intrinsic proteins in sensitive and tolerant rice during chilling and recovery

寒心的损害的症状是在射击的水赤字的开发，源于水运输和蒸发的不平衡。在这个工作，二个米饭变化(Oryza sativa L。var。Wasetoitsu 和 Somewake ) 幼苗是在 7 度 C 的 chilled，在 28 度 C 由恢复列在后面。基于生长显型和电解质漏测试， Somewake 被显示是一个寒心容忍的变化，和 Wasetoitsu 寒心敏感的。寒心的压力显著地减少了叶子，积聚的蒸发和渗透的根的相对的水内容(RWC ) 在两个变化的水力的电导率(Lp ) 。但是当回到了 28 度 C 时， Somewake 的水关系平衡更好恢复了。所有 11 血浆膜的 mRNA 表示侧面内在的蛋白质(果仁) ， aquaporins 的亚群，被有 TaqMan 次要的林子文件夹(MGB ) 的 -PCR 探查的即时反向的抄写(RT ) 随后决定源于米饭 var。Nipponbare 在寒心的处理和恢复期间。大多数 PIP 基因在低温度是下面调整的，并且在温暖的温度恢复了。在 Somewake 和 Wasetoitsu 的一些果仁的相对表示在平行减少了在期间寒心。然而在恢复期间， OsPIP1 的相对表示； 1， OsPIP2； 1， OsPIP2； 7 在射击和 OsPIP1； 1， OsPIP2； 1 比 Wasetoitsu 在 Somewake 在根是显著地更高的。这在在寒心的条件以后重建水平衡支持果仁的角色。我们讨论 aquaporin 果仁亚科的成员在植物起的多样化的作用寒心的忍耐取决于 aquaporin isoforms，植物织物和寒心的持续时间的阶段。

PREPARATION AND PROPERTIES OF WHEAT GLUTEN/RICE PROTEIN COMPOSITES PLASTICIZED WITH GLYCEROL

Environment friendly thermosetting composites were prepared by blending wheat gluten （WG） and rice protein （RP） at different weight ratios with glycerol as plasticizer followed by compression molding the mixture at 120℃ to crosslink the proteins. Reducing agent of sodium bisulfate and sodium sulfite and crosslinking agent formaldehyde were used to adjust the properties of the composites. Morphology, moisture absorption and tensile properties were evaluated. The results showed that formaldehyde could increase tensile strength of the composites without significant influence on Young＇s modulus and elongation at break. On the other hand, reducing agents could improve tensile strength and extensibility simultaneously, which was much marked at WG/RP ratios from 7/3 to 3/7.

Effect of Rice Bran Quality and Protein Supplement, Base Mix, and/or Soybean Meal on Growing Pig Performance in Cambodia

The objective of this study was to evaluate the effect of rice bran quality and dietary supplement source on growing pig performance. A total of 60 castrated male pigs (Yorkshire × Duroc, initially 16.1 kg) were used for 52-day trial. Pigs were allotted to pens in a completely randomized design (4 pigs per pen) and assigned to four dietary treatments in a 2 × 2 factorial with factors being rice bran source (high or low-quality) and source of protein, vitamins, and minerals (supplement or soybean meal and base mix). Analyzed protein and fat level for the high- and low-quality rice bran was 11.07% and 5.86% and 11.20% and 4.50%, respectively. Crude fiber content for high- and low-quality rice bran was 13.44% and 27.79%. Diets were formulated in two phases (phase 1: 16 to 27 and phase 2: 27 to 48 kg) to adjust to the pig’s nutrient requirements. There was no evidence for an interaction (P > 0.05) between rice bran quality × supplement type or main effect of supplement type (soybean meal + base mix vs protein supplement) for final body weight, average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (F/G). However, pigs fed high-quality rice bran had improved (P < 0.001) ADG and F/G and lower ADFI compared to pigs fed low protein rice bran. In conclusion, rice bran quality as measured by protein, crude fiber, and fat influenced growing pig performance, while the type of dietary protein supplement did not. Additionally, rice bran with high protein, fat, and low fiber improved ADG and F/G.

Optimization of High-Protein Glutinous Rice Flour Production Using Response Surface Method

A response surface method was employed to study the effect of α-amylase concentration, hydrolysis temperature and time on the production of high protein glutinous rice flour(HPGRF). The suspension of glutinous rice flour(15%) that contained 6.52% protein was gelatinized and subsequently hydrolyzed by thermostable α-amylase. The hydrolysis yielded 0.144–0.222 g/g HPGRF with 29.4%–45.4% protein content. Hydrolysis time exerted a significant effect, while enzyme concentration and hydrolysis temperature showed insignificant effect on the protein content and production yield of HPGRF. The result of response surface method showed that the optimum condition for the production of HPGRF that contained at least 36% protein was treating gelatinized 15% glutinous rice flour suspension with 0.90 Kilo Novo α-amylase Unit(KNU)/g α-amylase at 80 oC for 99 min. By carrying out the predicted hydrolysis condition, HPGRF with 35.9% protein and 61.8% carbohydrates was resulted. The process yielded 0.172 g/g HPGRF. HPGRF contained higher amount of essential amino acids compared to glutinous rice flour. HPGRF had higher solubility and lower swelling power, and also showed no pasting peak compared with glutinous rice flour.

Rice leaf inclination2, a VIN3-1ike protein, regulates leaf angle through modulating cell division of the collar

作为一个重要农学的特点，叶子的倾斜为庄稼建筑学和谷物收益是关键的。理解控制米饭叶角度的分子的机制，一米饭叶 inclination2 (lc2，三等位基因) 异种被识别并且机能上地描绘了。比作野类型的植物， lc2 异种在薄板的近轴的外皮由于增加的细胞分割扩大了叶角度关节。LC2 基因通过位置的克隆被孤立，并且编码开花结实促进法感觉迟钝的 3-like 蛋白质。LC2 的互补表示颠倒了 lc2 植物的扩大的叶角度，证实它在控制叶倾斜的角色。LC2 主要在叶开发期间在薄板关节被表示，并且特别地，被植物激素 abscisic 酸， gibberellic 酸，植物生长素，和 brassinosteroids 导致。LC2 在原子核是局部性的， LC2 的缺点导致房间分割和荷尔蒙应答的基因的改变的表示，显示在调整叶倾斜和调停的荷尔蒙效果的 LC2 的一个重要角色。

Effects of Uniconazole on Nitrogen Metabolism and Grain Protein Content of Rice

The effects of uniconazole by soaking seeds and spraying leaves at booting stage with different concentrations （0, 20 and 40 mg/kg） on the nitrogen metabolism of flag leaf and grains after flowering, and rice grain protein content and yield were studied with hybrid rice combination Shanyou 63. Under uniconazole treatment, the soluble protein content in flag leaf was increased in early and middle period of grain filling, but this content was nearly the same as or even lower than that of control at maturity; Glutamine synthetase activity in superior and inferior grains and non-protein nitrogen content in superior grains at early stage of grain development were promoted, and moreover, the transforming speed from non-protein nitrogen to protein nitrogen was accelerated; Non-protein nitrogen content was lower than that of control at maturity, but protein nitrogen content at each stage was higher than those of control; Protein nitrogen content in superior and inferior grains and protein nitrogen absolutely accumulative content in a grain both were enhanced and protein content and yield in rice grain were raised. The application of uniconazole by soaking seeds and spraying leaves raised crude protein content by an average of 7.2% and 8.3%, and protein yield by an average of 13.1% and 13.4%, respectively.

Western blot detection of PMI protein in transgenic rice

Phosphomannose isomerase （PMI） encoding gene manA is a desirable selective marker in transgenic research. Under- standing of its expression patterns in transgenic plant and establishing highly sensitive detection method based on immunoassay have great impacts on the application of PMI. In this study, PMI-specific monoclonal antibodies were generated using recombinant protein as immunogen, and could be used in Western blot to detect as little as 0.5 ng His-tagged PMI protein or rice expressed PMI protein in sample accounted for 0.4% of single rice grain （about 0.08 mg）. PMI protein driven by CaMV-35S promoter was detected in dozens of tested tissues, including root, stem, leaf, panicle, and seed at all developmental stages during rice growing, and PMI protein accounted for about 0.036% of total protein in the leaves at seedling stage. The established method potentially can be used to monitor PMI protein in rice grains.

Protein Phosphorylation and Phosphoproteome:An Overview of Rice

Protein phosphorylation,one of the major post-translational modifications,plays a crucial role in cell signaling,DNA replication,gene expression and differentiation;and alters enzyme activity and other biological activities;and regulates cell proliferation and enlargement,phytohormone biosynthesis and signaling,plant disease resistance,and grain filling and quality during rice seed development.Research work on protein phosphorylation started in the 1950 s with the discovery of phosphorylase a and phosphorylase b which are phospho and dephospho forms of the same enzyme.Over the last decade,rice proteomics has accomplished tremendous progress in setting up techniques to proteome nearly all tissues,organs and organelles.The progress made in this field is evident in number of research works.However,research on rice protein phosphorylation is still at its infancy and there are still many unanswered questions.In this review,the general description of protein phosphorylation,including history,structure,frequency of occurrence and function,are discussed.This work also elucidates the different methods for identification,qualification and finally,the progress in rice phosphoproteome research and perspectives.

Effects of Different Nitrogen Fertilizer Levels and Native Soil Properties on Rice Grain Fe, Zn and Protein Contents

Deposition of protein and metal ions （Fe, Zn） in rice grains is a complex polygenic trait showing considerable environmental effect. To analyze the effect of nitrogen application levels and native soil properties on rice grain protein, iron （Fe） and zinc （Zn） contents, 32 rice genotypes were grown at three different locations each under 80 and 120 kg/hm2 nitrogen fertilizer applications. In treatments with nitrogen fertilizer application, the brown rice grain protein content （GPC） increased significantly （1.1% to 7.0%） under higher nitrogen fertilizer application （120 kg/hm2） whereas grain Fe/Zn contents showed non-significant effect of nitrogen application level, thus suggesting that the rate of uptake and translocation of macro-elements does not influence the uptake and translocation of micro-elements. The pH, organic matter content and inherent Fe/Zn levels of native soil showed significant effects on grain Fe and Zn contents of all the rice genotypes. Grain Zn content of almost all the tested rice genotypes was found to increase at Location III having loamy soil texture, neutral pH value （pH 6.83） and higher organic matter content than the other two locations （Locations I and II）, indicating significant influence of native soil properties on brown rice grain Zn content while grain Fe content showed significant genotype × environment interaction effect. Genotypic difference was found to be the most significant factor to affect grain Fe/Zn contents in all the tested rice genotypes, indicating that although native soil properties influence phyto-availability of micronutrients and consequently influencing absorption, translocation and grain deposition of Fe/Zn ions, yet genetic makeup of a plant determines its response to varied soil conditions and other external factors. Two indica rice genotypes R-RF-31 （27.62 μg/g grain Zn content and 7.80% GPC） and R1033-968-2-1 （30.05 μg/g grain Zn content and 8.47% GPC） were identified as high grain Zn and moderate GPC rice genotypes. These results indicate that soil property and organic matter content increase the availability of Fe and Zn in rhizosphere, which in turn enhances the uptake, translocation and redistribution of Fe/Zn into rice grains.

Heterotrimeric G protein α subunit is involved in rice brassinosteroid response

Heterotrimeric G proteins are known to function as messengers in numerous signal transduction pathways.The nullmutation of RGA(rice heterotrimeric G protein α subunit),which encodes the α subunit of heterotrimeric G proteinin rice,causes severe dwarfism and reduced responsiveness to gibberellic acid in rice.However,less is known aboutheterotrimeric G protein in brassinosteroid(BR)signaling,one of the well-understood phytohormone pathways.In thepresent study,we used root elongation inhibition assay,lamina inclination assay and coleoptile elongation analysis todemonstrated reduced sensitivity of dl mutant plants(caused by the null mutation of RGA)to 24-epibrassinolide(24-epiBL),which belongs to brassinosteroids and plays a wide variety of roles in plant growth and development.Moreover,RGA transcript level was decreased in 24-epiBL-treated seedlings in a dose-dependent manner.Our results show thatRGA is involved in rice brassinosteroid response,which may be beneficial to elucidate the molecular mechanisms of Gprotein signaling and provide a novel perspective to understand BR signaling in higher plants.

Preliminary Study on Function of Calcineurin B-Like Protein Gene OsCBL8 in Rice

The homozygous T3 transgenic lines with sense OsCBL8 gene and antisense OsCBL8 gene obtained by agro-transformation were used to investigate the function of OsCBL8 in rice. Semi-quantitative RT-PCR showed that the expression of OsCBL8 extremely increased in sense transgenic lines, and decreased to some extents in antisense transgenic lines. Such up- and down-regulation of the OsCBL8 gene in these transgenic lines had little effects on main agronomic traits, but significantly decreased the number of filled grains per panicle and seed setting rate in some of transgenic lines. By evaluation of the tolerance to 150 mmol/L NaCl, 20% PEG6000 and low temperature treatments, and relevant physiological indices, 8F12, a sense transgenic line with high salt tolerance, and 8R14, an antisense transgenic line with high drought tolerance, were obtained, which suggests that the OsCBL8 gene is involved in the response of rice to abiotic stresses.

Genetic Diversity of Seed Storage Proteins in Different Ecotype Varieties of japonica Rice and Its Application

One hundred and fifteen varieties （including cultivars and lines） with different ecotypes in japonica rice （Oryza sativa L.） were analyzed for endosperm storage proteins by sodium dodecyl sulfate polyacrylamide gel electrophoresis （SDS-PAGE） to estimate their genetic diversity for the purpose of genetic improving and variety identification. Nineteen types of profile were identified according to 1） presence/absence of 65 kDa bands, 2） staining intensity of 70, 60, 57, 37-39, 22-23, 13 and 10 kDa bands, 3） migration velocity of 35 kDa （α-4） and 4） band number at 57 kDa location. An unweighted-pair group average method with arithmetic mean （UPGMA） dendregram based on the cluster analysis of genetic similarity of the protein bands showed a small genetic variation among the tested materials, with the similarity coefficients varying between 0.75 and 1.00. Three distinct groups were identified from the cluster analysis of the rice varieties studied at the similarity coefficient level of 0.894. The first group included eight varieties with high amylose content, the second group contained fifteen varieties with high protein content, and the third group had the remaining ninety-two varieties, which accounted for 80% of the total materials. Clear relationship between ecotypes distinguished by maturity and groups revealed by cluster analysis was not found in this study. Only the group of high amylose linked with medium-maturity medium japonica ecotype. The bands of 70 kDa and 65 kDa can be used as protein markers to identify F1 seed purity of japonica hybrid rice Liuyanyou 422.

Effects of 1,2,4-Trichlorobenzene and Mercury Ion Stress on Ca^2+ Fluxion and Protein Phosphorylation in Rice

The effects of 5 mg/L 1,2,4-trichlorobenzene （TCB） and 0.1 mmol/L mercury ion （Hg^2＋） stresses on Ca^2＋ fluxion and protein phosphorylation in rice seedlings were investigated by isotope exchange kinetics and in vitro phosphorylation assay. The Ca^2＋ absorption in rice leaves and Ca^2＋ transportation from roots to leaves were promoted significantly in response to Hg^2＋ and TCB treatments for 4-48 h. The Ca^2＋ absorption peaks presented in the leaves when the rice seedlings were exposed to Hg^2＋ for 8-12 h or to TCB for 12-24 h. Several Ca^2＋ absorption peaks presented in the roots during rice seedlings being exposed to Hg^2＋ and TCB, and the first Ca^2＋ absorption peak was at 8 h after being exposed to Hg^2＋ and TCB The result of isotope exchange kinetic analysis confirmed that short-term （8 h） Hg^2＋ and TCB stresses caused Ca^2＋ channels or pumps located on plasmalemma to open transiently. The phosphorylation assay showed that short-term TCB stress enhanced protein phosphorylation in rice roots （TCB treatment for 4-8 h） and leaves （TCB treatment for 4-24 h）, and short-term （4-8 h） Hg^2＋ stress also enhanced protein phosphorylation in rice leaves. The enhancement of protein phosphorylation in both roots and leaves corresponded with the first Ca^2＋ absorption peak, which confirmed that the enhancement of protein phosphorylation caused by TCB or Hg^2＋ stress might be partly triggered by the increases of cytosolic calcium. TCB treatment over 12 h inhibited protein phosphorylation in rice roots, which might be partly due to that TCB stress suppressed the protein kinase activity. Whereas, Hg^2＋ treatment inhibited protein phosphorylation in rice roots, and Hg^2＋ treatment over 12 h inhibited protein phosphorylation in rice leaves. This might be attributed to that not only the protein kinase activity, but also the expressions of phosphorylation proteins were restrained by Hg^2＋ stress.

Impacts of Environmental Factors on Degradation of CrylAb Insecticidal Protein in Leaf-Blade Powders of Transgenic Bt Rice

The determination of the environmental fate of Bt insecticidal protein released by Bt rice plants in paddy soils is a key issue in its ecological risk assessment. In this study, the impacts of soil water content, pH, and temperature on the degradation of CrylAb protein expressed in the leaves of Bt rice KMD2 were studied in the laboratory. Three types of paddy soils were used, i.e., blue clayey paddy soil, pale paddy soil on quaternary red soil, and marine-fluvigenic yellow loamy paddy soil. Ground powders of KMD2 leaf blades were mixed with each type of soil, and degradation dynamics of Cry lAb were measured using enzyme-linked immunosorbent assay （ELISA）. The degradation rate of CrylAb was high at the early experimental stage, but slowed down steadily at middle and later stages, which could be described by exponential equations, with the half-life period of degradation determined as 1.8-4.0 d. The soil water content, pH, and temperature could affect the degradation of CrylAb, but the effects of soil pH and temperature were relatively greater. In general, CrylAb degradations were slower under lower soil pH and temperature conditions, especially for marine-fluvigenic yellow loamy paddy soil.

Water Stress Effects on Leaf Growth and Chlorophyll Content but Not the Grain Yield in Traditional Rice (<i>Oryza sativa</i>Linn.) Genotypes of Assam, India II. Protein and Proline Status in Seedlings under PEG Induced Water Stress

Abiotic stresses can directly or indirectly affect the physiological status of an organism by altering its metabolism, growth, and development. The leaf growth and Chlorophyll content has significantly shown to vary from the control ones while the grain yield was not affected. While many plant species naturally accumulate proline and protein as major organic osmolytes when subjected to different abiotic stresses. These compounds are thought to play adaptive roles in mediating osmotic adjustment and protecting sub cellular structures in stressed plants. Different approaches have been contemplated to increase the concentrations of proline like compounds in plants grown under stress conditions to increase their stress tolerance. Seven different traditional rice varieties of Assam were evaluated for their response to osmolyte production under physiological drought condition through simulation at three levels of osmotic stress of 0.15 bar, 0.25 bar and 0.56 bar of physiological drought initiated by polyethylene glycol (PEG 6000). Along with the evaluation for osmolyte response the different components of genotypic variation for six different drought-sustaining characters in the seven rice varieties were also substantiated. The results indicated that plant height and seed number have significant genotypic coefficient of variability (GCV) and heritability. Verities like Laodubi, Leserihali, Beriabhanga and Borah were screened out as the best drought sustaining variety.

iTRAQ-Based Proteomics Investigation of Critical Response Proteins in Embryo and Coleoptile During Rice Anaerobic Germination

Direct-seeding of rice has become popular in recent years due to its low cost and convenience,however,hypoxic condition limits seedling establishment.In this study,weedy rice WR04-6 with high germination ability under anaerobic conditions was used as a gene donor,and we successfully improved the seedling establishment rate of rice cultivar Qishanzhan(QSZ)based on selection of a new rice line R42 from the recombinant inbred line population.R42 inherited high anaerobic germination(AG)ability,and was used for isobaric tags for relative and absolute quantitation(iTRAQ)-based comparative proteomic studies with QSZ to further explore the molecular mechanism of AG.A total of 719 differentially abundant proteins(DAPs)were shared by R42 and QSZ responded to AG,and thus defined as common response DAPs.A total of 300 DAPs that responded to AG were only identified from R42,which were defined as tolerance-specific DAPs.The common response and tolerance-specific DAPs had similar biochemical reaction processes and metabolic pathways in response to anoxic stress,however,they involved different proteins.The tolerance-specific DAPs were involved in amino acid metabolism,starch and sucrose metabolism,tricarboxylic acid cycle pathway,ethylene synthesis pathway,cell wall-associated proteins and activity of active oxygen scavenging enzyme.The in silico protein-protein interactions for the top 60 DAPs indicated that tolerance-specific DAPs had relatively independent protein interaction networks in response to an anoxic environment compared with common response DAPs.The results of physiological indicators showed thatα-amylase and superoxide dismutase activities of R42 were significantly increased under anoxic conditions compared with aerobic conditions.Multiple lines of evidence from western blot,physiological analysis and quantitatDirect seeding of rice has become popular in recent years due to its low cost and convenience,however,hypoxic conditions can limit seedling establishment.In the present study,weedy rice WR04-6 with high germination ability in anaerobic conditions was used as the gene donor and successfully improved the seedling establishment rate of rice cultivar Qishanzhan(QSZ)based on selection of a new rice line R42 from the recombinant inbred line(RIL)population.R42 inherited the had high anaerobic germination(AG)ability,which was used for the isobaric tags for relative and absolute quantitation(iTRAQ)based comparative proteomic studies with QSZ to further explore the molecular mechanism of AG.A total of 719 differentially abundant proteins(DAPs)shared by R42 and QSZ responded to AG and were thus defined as common response DAPs.A total of 300 DAPs that responded to AG were only identified from R42,which were defined as tolerance-specific DAPs.The common response and tolerance-specific DAPs had similar biochemical reaction processes and metabolic pathways in response to anoxic stress,however they involved different proteins.The 300 tolerance-specific DAPs were involved in amino acid metabolism,starch and sucrose metabolism,TCA cycle pathways,ethylene synthesis pathway,cell wall-associated proteins and activity of active oxygen scavenging enzyme.The in silico protein-protein interactions for the top 60 DAPs indicated that tolerance-specific DAPs had relatively independent protein interaction networks in response to an anoxic environment compared with common response DAPs.The results of physiological indicators showed thatα-amylase and SOD activities of R42 were significantly increased under anoxic conditions compared with aerobic conditions.Multiple lines of evidence from western blot,physiological analyses and real-time PCR jointly supported the reliability of proteomics data.In summary,our findings deepened the understanding of the molecular mechanism for the rice response to AG.ive real-time PCR jointly supported the reliability of proteomics data.In summary,our findings deepened the understanding of the molecular mechanism for the rice response to AG.