Comparative Analysis of the Endosperm Proteins Separated by 2-D Electrophoresis for Two Cultivars of Hybrid Rice （Oryza sativa L,）

Liangyoupeijiu is a two-parental-line, and Shanyou63 is a three-parental-line hybrid rice （Oryza sativa L.）. Although both belong to the indica subspecies, they have obvious differences with respect to morphology, physiology and grain quality. Variations in endosperm protein compositions were studied by comparing the 2-D electrophoresis （2-DE） maps for these two cultivars of hybrid rice. After matrix-assisted laser desorption/ionization time of flight mass spectrometry （MALDI-TOF/MS） analysis, a 21-kDa precursor of 19- kDa globulin was identified as the major storage protein for both cultivars. Some isoforms of peroxiredoxin and seed maturation protein were found to only exist in Shanyou63, whereas aldose reductase and starch granule-bound starch synthase were only detected in Liangyoupeijiu. These data might provide a foundation for further comparative studies of these two cultivars of hybrid rice.     

Role of plant myosins in motile organelles: Is a direct interaction required?

Plant organelles are highly motile, with speed values of 3–7 m m/s in cells of land plants and about20–60 m m/s in characean algal cells. This movement is believed to be important for rapid distribution of materials around the cell, for the plant's ability to respond to environmental biotic and abiotic signals and for proper growth. The main machinery that propels motility of organelles within plant cells is based on the actin cytoskeleton and its motor proteins the myosins.Most plants express multiple members of two main classes:myosin VIII and myosin XI. While myosin VIII has been characterized as a slow motor protein, myosins from class XI were found to be the fastest motor proteins known in al kingdoms. Paradoxically, while it was found that myosins from class XI regulate most organelle movement, it is not quite clear how or even if these motor proteins attach to the organelles whose movement they regulate.     

Roles of Thioredoxins in the Obligate Anaerobic Green Sulfur Photosynthetic Bacterium Chlorobaculum tepidum

Thioredoxin is a small ubiquitous protein that is involved in the dithiol-disulfide exchange reaction, byway of two cysteine residues located on the molecule surface. In order to elucidate the role of thioredoxin in Chlorobaculum tepidurn, an anaerobic green sulfur bacterium that uses various inorganic sulfur compounds and H2S as electron donors under strict anaerobic conditions for growth, we applied the thioredoxin affinity chromatography method （Motohashi et al., 2001）. In this study, 37 cytoplasmic proteins were captured as thioredoxin target candidates, including proteins involved in sulfur assimilation. Furthermore, six of the candidate proteins were members of the reductive tricarboxylic acid cycle （pyruvate orthophosphate dikinase, pyruvate flavodoxin/ferredoxin oxidoreductase, ~-oxoglutarate synthase, citrate lyase, citrate synthase, malate dehydrogenase）. The redox sensitivity of three enzymes was then examined： citrate lyase, citrate synthase, and malate dehydrogenase, using their recombinant proteins. Based on the information relating to the target proteins, the significance of thioredoxin as a reductant for the metabolic pathway in the anaerobic photosynthetic bacteria is discussed.     

Selective degradation of the IκB kinase （IKK） by autophagy

Proteasome-mediated degradation and autophagy are the two major pathways mediating the turnover of cellular proteins. The proteasomal pathway is known to be a highly specific and regulated process mediating the degradation of short-lived proteins such as many important factors involved in cellular signaling. In contrast, it is generally thought that autophagy is rather nonselective as it is responsible for the bulk degradation of long-lived proteins and organelles. Challenging this general view, in this issue of Cell Research, Qing et al. report that selective degradation of the IκB kinase （IKK） triggered by the loss of Hsp90 function is mediated by autophagy [1].     

Proteome analysis of rice root proteins regulated by gibberellin

To gain an enhanced understanding of the mechanism by which gibberellins （GAs） regulate the growth and development of plants, it is necessary to identify proteins regulated by GA. Proteome analysis techniques have been applied as a direct, effective, and reliable tool in differential protein expressions. In previous studies, sixteen proteins showed differences in accumulation levels as a result of treatment with GA3, uniconazole, or abscisic acid （ABA）, and/or the differences between the GA-deficient semi-dwarf mutant, Tan-ginbozu, and normal cultivars. Among these proteins, aldolase increased in roots treated with GA3, was present at low levels in Tan-ginbozu roots, and decreased in roots treated with uniconazole or ABA. In a root elongation assay, the growth of aldolase-antisense transgenic rice was half of that of vector control transgenic rice. These results indicate that increases in aldolase activity stimulate the glycolytic in the GA-induced growth of roots. In among GA, aldolase, and root growth. pathway and may play an important role this review, we discuss the relationship among GA, aldolase, and root growth.     

Microarray and proteomic analysis of brassinosteroid- and gibberellin-regulated gene and protein expression in rice

Brassinosteroid (BR) and gibberellin (GA) are two groups of plant growth regulators essential for normal plant growth and development. To gain insight into the molecular mechanism by which BR and GA regulate the growth and development of plants, especially the monocot plant rice, it is necessary to identify and analyze more genes and proteins that are regulated by them. With the availability of draft sequences of two major types, japonica and indica rice, it has become possible to analyze expression changes of genes and proteins at genome scale. In this review, we summarize rice functional genomic research by using microarray and proteomic approaches and our recent research results focusing on the comparison of cDNA microarray and proteomic analyses of BR- and GA-regulated gene and protein expression in rice. We believe our findings have important implications for understanding the mechanism by which BR and GA regulate the growth and development of rice.     

Development of the “Third-Generation” Hybrid Rice in China

Rice is a major cereal crop for China. The development of the ‘‘three-line" hybrid rice system based on cytoplasmic male sterility in the 1970 s(first-generation) and the ‘‘two-line" hybrid rice system based on photoperiod-and thermo-sensitive genic male-sterile lines(second-generation)in the 1980 s has contributed significantly to rice yield increase and food security in China. Here we describe the development and implementation of the ‘‘third-generation" hybrid rice breeding system that is based on a transgenic approach to propagate and utilize stable recessive nuclear male sterile lines, and as such, the male sterile line and hybrid rice produced using such a system is nontransgenic. Such a system should overcome the intrinsic problems of the ‘‘first-generation" and‘‘second-generation" hybrid rice systems and hold great promise to further boost production of hybrid rice and other crops.     

Predicting protein subcellular location using digital signal processing

The biological functions of a protein are closely related to its attributes in a cell. With the rapid accumulation of newly found protein sequence data in databanks, it is highly desirable to develop an automated method for predicting the subcellular location of proteins. The establishment of such a predictor will expedite the functional determination of newly found proteins and the process of prioritizing genes and proteins identified by genomic efforts as potential molecular targets for drug design. The traditional algorithms for predicting these attributes were based solely on amino acid composition in which no sequence order effect was taken into account. To improve the prediction quality, it is necessary to incorporate such an effect. However, the number of possible patterns in protein sequences is extremely large, posing a formidable difficulty for realizing this goal. To deal with such difficulty, a well-developed tool in digital signal processing named digital Fourier transform (DFT) [1] was introduced. After being translated to a digital signal according to the hydrophobicity of each amino acid, a protein was analyzed by DFT within the frequency domain. A set of frequency spectrum parameters, thus obtained, were regarded as the factors to represent the sequence order effect. A significant improvement in prediction quality was observed by incorporating the frequency spectrum parameters with the conventional amino acid composition. One of the crucial merits of this approach is that many existing tools in mathematics and engineering can be easily applied in the predicting process. It is anticipated that digital signal processing may serve as a useful vehicle for many other protein science areas.     

Rice Mitogen-activated Protein Kinase Gene Family and Its Role in Biotic and Abiotic Stress Response

The mitogen-activated protein kinase （MAPK） cascade is an important signaling module that transduces extracellular stimuli into intracellular responses in eukaryotic organisms. An increasing body of evidence has shown that the MAPK-mediated cellular signaling is crucial to plant growth and development, as well as biotic and abiotic stress responses. To date, a total of 17 MAPK genes have been Identified from the rice genome. Expression profiling, biochemical characterization and/or functional analysis were carried out with many members of the rice MAPK gene family, especially those associated with biotic and abiotic stress responses. In this review, the phylogenetic relationship and classification of rice MAPK genes are discussed to facilitate a simple nomenclature and standard annotation of the rice MAPK gene family. Functional data relating to biotic and abiotic stress responses are reviewed for each MAPK group and show that despite overlapping in functionality, there is a certain level of functional specificity among different rice MAP kinases. The future challenges are to functionally characterize each MAPK, to identify their downstream substrates and upstream kinases, and to genetically manipulate the MAPK signaling pathway in rice crops for the Improvement of agronomically important traits.     

Characterization of photosynthesis, photoinhibition and the activities of C4 pathway enzymes in a superhigh-yield rice, Liangyoupeijiu

Characteristics of photosynthetic gas exchange, photoinhibition and C4 pathway enzyme activities in both flag leaves and lemma were compared between a superhigh-yield rice (Oryza sativa L.) hybrid, Liangyoupeijiu and a traditional rice hybrid, Shanyou63. Liangyoupeijiu had a similar light saturated assimilation rate (Asat) to Shanyou63, but a much higher apparent quantum yield (AQY), carboxylation efficiency (CE) and quantum yield of CO2 fixation (φCO2). Liangyoupeijiu also showed a higher resistance to photoinhibition and higher non-radiative energy dissipation associated with the xanthophyll cycle than Shanyou63 when subjected to strong light. In addition, Liangyoupeijiu had higher activities of the C4 pathway enzymes in both flag leaves and lemmas than Shanyou63. These results indicate that higher light and CO2 use efficiency, higher resistance to photoinhibition and C4 pathway in both flag leaf and lemma may contribute to the higher yield of the superhigh-yield rice hybrid, Liangyoupeijiu.     

水稻冠层光截获、光能利用与产量的关系

以两优培九和武香粳14号水稻品种为材料,在不同栽插密度和施氮水平下进行2年田间试验,研究水稻冠层光合有效辐射(PAR)截获率、光能利用率与水稻产量的关系.结果表明:分蘖期至成熟期,各处理水稻冠层平均PAR反射率为3.45％,其中,分蘖期至抽穗期的冠层反射PAR占冠层总PAR损失的10.90％,显著小于抽穗期至成熟期的22.06％.分蘖期至成熟期的冠层PAR转化率随栽插密度的增加而减少,随施氮量的增加而增大;分蘖期至抽穗期的冠层PAR转化率高于抽穗期至成熟期.在分蘖期至成熟期,冠层PAR利用率随栽插密度和施氮量的增加而增大,各处理中两优培九的平均PAR利用率(1.83 g· MJ-1)显著高于武香粳14(1.42 g·MJ-1);武香粳14因生育期较长,分蘖期至成熟期的入射PAR及中、高栽插密度处理的PAR截获量均高于两优培九.水稻不同生长阶段冠层PAR截获率和利用率与产量呈显著正相关,PAR转化率与产量也呈正相关,但相关性不显著.因此,在保持较高PAR截获率的基础上提高冠层PAR转化率,进而提高冠层PAR利用率,有利于水稻高产.     

水稻冠层光截获、光能利用与产量的关系

以两优培九和武香粳14号水稻品种为材料,在不同栽插密度和施氮水平下进行2年田间试验,研究水稻冠层光合有效辐射(PAR)截获率、光能利用率与水稻产量的关系.结果表明： 分蘖期至成熟期,各处理水稻冠层平均PAR反射率为3.45%,其中,分蘖期至抽穗期的冠层反射PAR占冠层总PAR损失的10.90%,显著小于抽穗期至成熟期的22.06%.分蘖期至成熟期的冠层PAR转化率随栽插密度的增加而减少,随施氮量的增加而增大;分蘖期至抽穗期的冠层PAR转化率高于抽穗期至成熟期.在分蘖期至成熟期,冠层PAR利用率随栽插密度和施氮量的增加而增大,各处理中两优培九的平均PAR利用率(1.83 g·MJ^-1)显著高于武香粳14(1.42 g·MJ^-1);武香粳14因生育期较长,分蘖期至成熟期的入射PAR及中、高栽插密度处理的PAR截获量均高于两优培九.水稻不同生长阶段冠层PAR截获率和利用率与产量呈显著正相关,PAR转化率与产量也呈正相关,但相关性不显著.因此,在保持较高PAR截获率的基础上提高冠层PAR转化率,进而提高冠层PAR利用率,有利于水稻高产.     

PSⅡ Photochemistry and Xanthophyll Cycle in Two Superhigh yield Rice Hybrids,Liangyoupeijiu and Hua an 3 During Photoinhibition and Subsequent Restoration

PSⅡ photochemistry and xanthophyll cycle during photoinhibition (exposed to strong light of 2 000 μmol photons·m-2·s-1) and the subsequent restoration were compared between two superhigh yield rice hybrids (Liangyoupeijiu and Hua an 3, the newly developed rice hybrids from two parental lines) and the traditional rice hybrid Shanyou 63 developed from three parental lines. The results showed that the maximal efficiency of PSⅡ photochemistry (Fv/Fm), the efficiency of excitation energy capture by open PSⅡ centers (Fv′/Fm′), and the yield of PSⅡ electron transport (ΦPSⅡ) of the three rice hybrids decreased during photoinhibition. However, a greater decrease in Fv/Fm, Fv′/Fm′, and ΦPSⅡ was observed in Shanyou 63 than in Liangyoupeijiu and Hua an 3. At the same time, the components of xanthophyll cycle, antherxanthin (A) and zeathanxin (Z) increased rapidly while violaxanthin (V) decreased considerably. Both the rate of accumulation and the amount of A and Z in the two superhigh yield rice hybrids were higher than that in Shanyou 63. The de epoxidation state (DES) of xanthophyll cycle increased rapidly with the fast accumulation of A and Z, and reached the maximal level after first 30 min during photoinhibition. Of the three hybrids, the increasing rate of DES in Liangyoupeijiu and Hua an 3 was higher than that in Shanyou 63. After photoinhibition treatment, the plant materials were transferred to a dim light (70 μmol photons·m-2·s-1) for restoration. During restoration, both chlorophyll fluorescence parameters and xanthophyll cycle relaxed gradually, but the rate and level of restoration in the two superhigh yield rice hybrids were higher than those in Shanyou 63. Our results suggest that Liangyoupeijiu and Hua an 3 had higher resistance to photoinhibition and higher capacity of non radiative energy dissipation associated with xanthophyll cycle, as well as higher rate of restoration after photoinhibition, than Shanyou 63 when subjected to strong light.     

Characterization of photosynthesis, photoinhibition and the activities of C4 pathway enzymes in a superhigh-yield rice, Liangyoupeijiu

Characteristics of photosynthetic gas exchange, photoinhibition and C₄ pathway enzyme activities in both flag leaves and lemma were compared between a superhigh-yield rice (Oryza sativa L.) hybrid, Liangyoupeijiu and a traditional rice hybrid, Shanyou63. Liangyoupeijiu had a similar light saturated assimilation rate (Asat) to Shanyou63, but a much higher apparent quantum yield (AQY), carboxylation efficiency (CE) and quantum yield of CO₂ fixation (ΦCO₂). Liangyoupeijiu also showed a higher resistance to photoinhibition and higher non-radiative energy dissipation associated with the xanthophyll cycle than Shanyou63 when subjected to strong light. In addition, Liangyoupeijiu had higher activities of the C₄ pathway enzymes in both flag leaves and lemmas than Shanyou63. These results indicate that higher light and CO₂ use efficiency, higher resistance to photoinhibition and C₄ pathway in both flag leaf and lemma may contribute to the higher yield of the superhigh-yield rice hybrid, Liangyoupeijiu.     

干湿交替灌溉下不同稗草种对水稻产量及生理特性的影响

以两优培九(籼稻)和南粳9108(粳稻)为材料,从移栽至成熟期分别与无芒稗(T₁)、稗(T₂)、西来稗(T₃)和光头稗(T₄)共生,以无稗草水稻处理为对照,研究干湿交替灌溉条件下不同稗草种对水稻产量和生理特性的影响.结果表明： 与对照相比,T₁、T₂、T₃和T₄处理下两优培九分别减产13.8%、10.6%、23.8%和0.5%,南粳9108分别减产45.5%、36.9%、60.7%和15.1%.T₁、T₂和T₃处理显著降低了水稻产量,T₄处理对两优培九产量无显著影响,但显著降低了南粳9108的产量.T₁、T₂、T₃和T₄处理增加了水稻灌浆期叶片丙二醛含量,降低了叶片中过氧化氢酶、过氧化物酶和超氧化物歧化酶的活性,降低了成熟期干物质积累量、灌浆期根系氧化力以及根系中吲哚-3-乙酸和玉米素+玉米素核苷的含量.4种处理对水稻各生理指标的影响程度为T₃>T₁>T₂>T₄.稻-稗共生时水稻灌浆期叶片抗氧化系统酶活性、根系氧化力、根系中吲哚-3-乙酸和玉米素+玉米素核苷含量及成熟期干物质积累量的降低以及灌浆期叶片丙二醛含量的增加是水稻减产的重要原因.     

超高产杂交稻光合特性的研究

比较了超高产杂交稻(Oryza sativa L.)X07S/紫恢100和两优培九与多年来大面积推广的杂交稻汕优63的光合功能和抗光胁迫能力.结果表明,超高产杂交稻X07S/紫恢100和两优培九的净光合速率(Pn)分别比汕优63高9.1%和11.9%,而其蒸腾速率(Tr)分别比汕优63低37.46%和31.42%,此外,其水分利用效率(WUE)分别比汕优63高出74.2%和63.5%;经强光(2 000μmol photons@m-2@s-1)处理2 h之后,X07S/紫恢100和两优培九的光系统Ⅱ光化学量子效率分别上升28.3%和37.0%,荧光光化学猝灭系数分别升高46.2%和18.0%,而汕优63的这两项参数值却变化很小;同时,X07S/紫恢100和两优培九的非光化学猝灭系数均下降50%左右,而汕优63则上升近50%,表明超高产杂交稻较高的光合能力、水分利用效率以及较强的抗光抑制能力可能是其高产的生理基础.     

Compatibility of glycinebetaine in rice plants: evaluation using transgenic rice plants with a gene for peroxisomal betaine aldehyde dehydrogenase from barley

Glycinebetaine is synthesized in plants by the two‐step oxidation of choline, with betaine aldehyde as the intermediate. The reactions are catalyzed by choline mono‐oxygenase and betaine aldehyde dehydrogenase. Rice plants, which do not accumulate glycinebetaine, possess a gene encoding betaine aldehyde dehydrogenase, whose activity is detectable at low levels. To evaluate the compatibility in rice of glycinebetaine on growth and tolerance to salt, cold and heat, we produced transgenic rice plants by introduction of a cDNA for betaine aldehyde dehydrogenase of barley, which is localized in peroxisomes unlike the chloroplast‐specific localization of betaine aldehyde dehydrogenase in spinach and sugar beet. The transgenic rice plants converted high levels of exogenously applied betaine aldehyde (up to 10 mol m^–3) to glycinebetaine more efficiently than did wild‐type plants. The elevated level of glycinebetaine in transgenic plants conferred significant tolerance to salt, cold and heat stress. However, very high levels of glycinebetaine, resulting from conversion of applied betaine aldehyde to glycinebetaine or from exogenous application, inhibited increases in length of rice plants but not increases in dry weight. Our results suggested that the benefits of accumulation of glycinebetaine by rice plants might be considerable under high light conditions.