Photothermal Responses of Flowering in Rice (Oryza sativa)

Durations from sowing to panicle emergence in 16 diverse genotypesof rice (Oryza sativa L.) were recorded in 13 different photothermalregimes, comprising constant and diurnally alternating temperaturesbetween 16 and 32 °C and photoperiods between 10.5 and 15.0h d^–1—all provided by controlled-environment growthcabinets. In 11.5 h days and at sub-optimal temperatures, relationsbetween the rate of progress towards panicle emergence and meantemperature were linear in all genotypes, and amongst thesethe base temperature at that photoperiod varied between 6.6and 11.9 °C. In most cases progress was most rapid at 24–26°C, i.e. the optimum temperature was much cooler than expectedfrom previously published values of times to panicle emergencein a less extensive range of photothermal regimes. Only in threecultivars was it warmer than 28 °C, and in these there weresufficient data to establish that relations between rates ofprogress to panicle emergence and photoperiod in the diurnallyalternating temperature regime of 28–20 °C are alsolinear. Also, the responses of these three cultivars provideno evidence of any interaction between the effects of photoperiodand temperature. We conclude, then, that the model in whichrate of development is a linear function of both temperatureand photoperiod with no interaction, which has been shown tobe common to many other species, also applies to rice. Differencesamong genotypes in relative sensitivity of rate of progresstowards panicle emergence to both temperature and to photoperiodwere considerable; japonica cultivars tended to be more sensitiveto temperature and less sensitive to photoperiod than indicacultivars. Four indica cultivars bred and selected at The InternationalRice Research Institute (IRRI) in the Philippines did not differ(P > 0.10) in their relations between rate of progress towardspanicle emergence and sub-optimal temperatures in a daylengthof 11.5 h, but the optimum temperature for cv. IR 36 was appreciablywarmer than that for the cvs IR 5, IR 8 and IR 42. Oryza sativa, rice, flowering, temperature, photoperiod, photothermal responses     

水稻响应缺铁的韧皮部汁液蛋白质组学分析

为鉴定水稻(Oryza sativa)响应缺铁的根冠长距离信号转导物质, 采用TMT标记技术分析了不同浓度铁处理下水稻韧皮部汁液的蛋白质组学变化, 共鉴定出206个差异蛋白, 其中54个蛋白表达丰度上调, 152个蛋白表达丰度下调。差异蛋白的KEGG通路分类主要包括激素信号代谢、谷胱甘肽代谢、碳代谢以及mRNA转运等代谢途径。此外, 对差异蛋白对应的生理指标进行测定, 发现激素、蔗糖、谷胱甘肽和转运蛋白等在缺铁条件下变化显著, 后续对这些差异蛋白的功能研究有助于揭示水稻响应铁素营养的长距离信号途径。     

Linkage Disequilibrium in Salt Tolerant Genotypes of Rice (Oryza sativa L)

Genome wide linkage disequilibrium (LD) was investigated in a set of 32 genotypes representing salt tolerant improved varieties and landraces and six salt sensitive genotypes of rice with 64 microsatellite markers to identify the genomic regions that are associated with salt tolerance in rice. Out of 64 markers analyzed, 36% SSR pairs exhibited significant LD at 0.05. A few regions were identified as targets of selection in 10 chromosomes with high r ² values. The model-based groups from Bayesian clustering analysis are largely consistent with known pedigrees of the lines. The increased percentage of association of SSR loci in the improved varieties indicated the role of selection in linkage disequilibrium especially for salt tolerance. LD was extended as far as 100 cM in the present study. Most of the markers (43.8%) with significant LD values were observed in the genomic regions of reported QTL for salt tolerance in rice.     

Ethylene-Induced Polyamine Accumulation in Rice (Oryza sativa L.) Coleoptiles

The light-harvesting complex (LHC) of photosystem II is composed of several different pigment-binding apoproteins. We have identified a cDNA clone LHCIIa-1 encoding the 31-kilodalton LHC IIa (CP29, Chl a/b-P1) apoprotein of barley (Hordeum vulgare). Direct protein microsequencing of an internal peptide fragment from the LHC IIa apoprotein has been used to identify unequivocally the cDNA clone as that coding for the LHC IIa apoprotein. Microsequencing of the 28-kilodalton LHC IIc protein (CP26) showed only minor sequence similarity to the LHC IIa protein, indicating that they are two different gene products. LHCIIa-1 codes for a protein of 286 amino acid residues (molecular weight, 31,308), which displays strong similarities to other pigment-binding LHC proteins, and yet contains an additional 42 amino acid residue segment. Two regions of strong intramolecular sequence similarity are also observed.     

Arsenate Causes Differential Acute Toxicity to Two P-deprived Genotypes of Rice Seedlings (Oryza sativa L.)

Significant genotypic difference in response to arsenate toxicity in rice (Oryza sativa) was investigated in root elongation, arsenate uptake kinetics, physiological and biochemical response and arsenic (As) speciation. Uptake kinetics data showed that P-deprived genotype 94D-54 had a little higher As uptake than P-deprived 94D-64, but the difference was not large enough to cause acute toxicity in P-deprived 94D-54. There was no difference in tissue P concentrations between the two genotypes under P deficient conditions. In addition, arsenic speciation in plant tissues (using high performance liquid chromatography-inductively coupled plasma mass spectrometry) was not different between P pretreatments and between genotypes. P-deprived genotype 94D-54 suffered much higher stress induced by arsenate toxicity than P-deprived genotype 94D-64, in terms of lipid peroxidation, tissue H₂O₂ concentrations and exosmosis of K, P and As. However, P-deprived 94D-54 also had higher overproduction of enzymatic antioxidants (with higher GPX, SOD, CAT) and NPT (non-protein thiols) than P-deprived 94D-64. It appeared that, the higher sensitivity of P-deprived 94D-54 to arsenate toxicity might cause the overproduction of NPT, thus leading to the depletion of GSH and to the accumulation of H₂O₂. The differential sensitivity of the two genotypes has major implications for breeding rice for As affected paddy soil.     

NaCl-induced Senescence in Leaves of Rice (Oryza sativa L.) Cultivars Differing in Salinity Resistance

The influence of NaCl on senescence-related parameters (proteinand chlorophyll concentrations, membrane permeability and chlorophyllfluorescence) was investigated in young and old leaves of fiverice cultivars differing in salt resistance. NaCl hastened thenaturally-occurring senescence of rice leaves which normallyappears during leaf ontogeny: it decreased chlorophyll and proteinconcentrations and increased membrane permeability and malondialdehydesynthesis. Such an acceleration of deteriorative processes affectedall leaves in salt-sensitive cultivars while it was more markedin oldest than in youngest leaves of salt-resistant genotypes.NaCl-induced senescence also involved specific modifications,such as an increase in basal non-variable chlorophyll fluorescence(F ₀) recorded in all cultivars or a transient increase in solubleprotein concentration recorded in salt-resistant genotypes only.Alteration of membrane permeability appeared as one of the firstsymptoms of senescence in rice leaves and allowed discriminationamong cultivars after only 7 d of stress. In contrast, F _v/F _mratio (variable fluorescence/maximal fluorescence) was thesame for all cultivars during the first 18 d of stress and thuscould not be used for identifying salt-resistant rice exposedto normal light conditions. Relationships between parametersinvolved in leaf senescence are discussed in relation to salinityresistance of rice cultivars. Chlorophyll concentration; chlorophyll fluorescence; electrolyte leakage; magnesium; malondialdehyde; membrane permeability; NaCl; Oryza sativa L.; protein; rice; salinity resistance; senescence; UV absorbing substances     

A Set of Three Genes Regulates Photoperiodic Responses of Flowering in Rice (Oryza sativa)

Differentiation in photoperiodic response of flowering has been key to the evolution and wide geographic distribution of rice, an essentially short-day plant. Crosses were made such that the hybrid F1 plants flower later than the late-flowering parents to investigate the genetic basis underlying this differentiation. From initial experiments, three major genes for flowering time were identified from four naturally occurring variants under natural long-day conditions. An F2-derived trigenic mutant line bred-true for a day-neutral response was selected and used as the recipient to synchronize the genetic background for the major genes. Experiments conducted under various daylengths indicated that these genes are responsible for photoperiodic sensitivity and the trihybrid has a critical daylength between 13.5 and 14 h. The three genes regulate photoperiodic responses qualitatively and quantitatively through complementary and other epistatic effects, respectively. The complementation suggests that the three genes act in a linear manner to repress the transition from the vegetative to reproductive phases under long daylengths. This set of genes also provides a model to understand the genetic mechanism underlying the elongated vegetative growth period in the F1 generation, which is usually an obstacle to the use of heterosis, and the selection for early maturation in rice breeding.     

Erratum to: The Effects of Exogenous Ascorbic Acid on the Mechanism of Physiological and Biochemical Responses to Nitrate Uptake in Two Rice Cultivars (Oryza sativa L.) Under Aluminum Stress

Journal of Plant Growth Regulation -     

Divergent Molecular and Physiological Response of Two Maize Breeding Lines Under Phosphate Deficiency

Plant Molecular Biology Reporter - Inorganic phosphate (Pi) deficiency is a main limiting factor on crops growth and to select low-Pi tolerant breeding lines is very significant for crop breeding....     

水稻染色体G—带的研究

用改良的ASG法首次在籼稻(O.sativa subsp.indica)品种珍汕97和粳稻(O.subsp.iaponica)品种秀岭的有丝分裂染色体上显示了G-带,并作了相应的G-带核型分析。就同一材料来说,随着有丝分裂时期的推进,染色体上带纹数目逐渐减少。籼、粳亚种间相对应的同源染色体上G-带带纹特征彼此相似。讨论了水稻G-带带型与染色体不同区域分化的关系;G-带带型与籼、粳稻分歧的关系;以及G-显带的方法。     

Desiccation Tolerance and Potential Longevity of Developing Seeds of Rice (Oryza sativa L.)

The longevity and desiccation tolerance of samples of seedsof a japonica rice (Oryza sativa L.) harvested serially duringdevelopment from plants grown in two temperature regimes, viz28/20 °C and 32/24 °C (12/12 h) were determined. Massmaturity (defined as the end of the seed-filling phase) occurred19·7 and 18·3 d after 50% anthesis, respectively.Longevity (determined at 40 °C with 15% moisture contentand quantified by the value of the constant K_i of the seed viabilityequation) improved during seed development and maturation until17 and 14 d after mass maturity in the cooler and warmer regimes,respectively, but declined thereafter. Changes in K_i with timewere similar in the two environments until mass maturity, butthe increase in K_i values after mass maturity was much greaterin the cooler regime. Tolerance of desiccation to low (4%) moisturecontents improved until 22 and 14 d after mass maturity in thecooler and warmer regimes, respectively, when maturation dryinghad reduced seed moisture contents naturally to 24 and 32% moisturecontent, respectively. Further delays to seed harvest reduceddesiccation tolerance, particularly in the warmer environment.Comparison among 15 samples of seeds harvested at differenttimes in the two environments showed a strong correlation (r= 0·947, P < 0·01) between longevity (K_i) anddesiccation tolerance (to 4% moisture content). Hence, it issuggested that the regulation of desiccation tolerance to lowmoisture contents and potential air-dry longevity during seeddevelopment and maturation determined here may have a commoncause.Copyright 1994, 1999 Academic Press Oryza sativa L., rice, desiccation tolerance, genebanks, seed development, seed longevity, temperature     

水稻对重金属元素的吸收与分配机理的研究进展

20世纪以来, 随着工业的快速发展及人口的大幅度增加, 重金属在环境中快速地积累。水稻(Oryza sativa)作为我国最重要的粮食作物, 稻田重金属污染不仅导致水稻生长发育受阻, 产量下降, 更为严重的是重金属在水稻体内大量累积, 并通过食物链传递, 危害人的健康, 直接影响我国的粮食安全。本文就水稻对有毒重金属元素的吸收、运输和分配及其机理方面的最新研究进展进行综述, 同时对今后的研究提出看法。     

矮泰引-3中半矮秆基因的分子定位

矮泰引-3的矮生性状受两对独立遗传的半矮秆基因控制,利用SSR标记将这两个矮秆基因分别定位到第1和第4染色体上。等位性测交的结果表明,位于第1染色体上的矮秆基因与sd1是等位的,所以仍然称其为sd1;而位于第4染色体上的矮秆基因是一个新基因,暂命名为sdt2。利用SSR标记将sd1定位于RM297、RM302和RM212的同一侧,而与OSR3共分离,它们之间的位置关系可能是RM297-RM302-RM212-OSR3-sd1,遗传距离分别为4．7cM、0cM、0．8cM和0cM,这与sd1在第1染色体长臂上的确切位置是基本一致的。利用已有的SSR标记和拓展的SSR标记将sdt2定位于SSR332、RM1305和RM5633、RM307、RM401之间,它们的排列位置可能是SSR332-RM1305-sdt2-RM5633-RM307-RM401,它们之间的遗传距离分别为11．6cM、3．8cM、0．4cM、0cM和0．4cM。     

水稻对重金属元素的吸收与分配机理的研究进展

20世纪以来,随着工业的快速发展及人口的大幅度增加,重金属在环境中快速地积累.水稻(Oryza sativa)作为我国最重要的粮食作物,稻田重金属污染不仅导致水稻生长发育受阻,产量下降,更为严重的是重金属在水稻体内大量累积,并通过食物链传递,危害人的健康,直接影响我国的粮食安全.本文就水稻对有毒重金属元素的吸收、运输和分配及其机理方面的最新研究进展进行综述,同时对今后的研究提出看法.     

两种供氮水平下水稻生长后期相关性状的QTL定位

以特青为母本与Lemont杂交,然后用特青为轮回亲本回交,建立特青背景下的染色体片段置换系（CSSL）群体。在正常和低氮条件下分别在生长后期对株高（PH）、单株穗数（PN）、叶绿素含量（CC）、地上部干物重（SDW）和单株籽粒产量（YD）等性状进行了QTL分析,共检测到31个QTL。其中在正常供氮水平下控制PH、PN、CC、SDW和YD的QTL数目均为3个;在低氮水平下检测到5、4、5和2个影响PH、PN、CC和SDW的QTL,在低氮水平下没有检测到控制YD的位点。大部分QTL集中在第2、3、7、11和12染色体上,影响不同性状或在两种供氮水平下影响同一性状的QTL在染色体上成串或成簇分布。其中RM30-RM439、RM18-RM478、RM309-RM270、RM235-RM17等区域同时检测到控制两个以上性状的QTL,表现出明显的一因多效现象。推测仅在低氮水平下检测到的QTL可能跟水稻对低氮胁迫耐性有一定的关联。     

Comparative Transcriptomic Analysis of Two Rice (Oryza sativa L.) Male Sterile Line Seed Embryos Under Accelerated Aging

Plant Molecular Biology Reporter - Seed aging is a complex and irreversible process during seed development and storage. The quality of parental seeds affects yield and quality of hybrid rice seeds...