中国水稻微核心种质不同生育时期耐冷性鉴定及其相关分析

以204份中国水稻微核心种质为试验材料,进行了水稻发芽期、芽期、幼苗期、孕穗期等耐冷性鉴定及其相关性分析。结果表明,水稻各生育时期耐冷性在籼粳亚种间、各种质之间存在明显的差异。粳稻种质的耐冷性明显强于籼稻种质,但籼稻种质中也存在耐冷性较强的种质。高阳淀稻大红芒、肥东塘稻、木樨球、卫国、兴国、山酒谷、中花8号等粳稻种质和包选21号、红米三担白、寸谷糯、红谷等籼稻种质在水稻各生育时期均表现较强的耐冷性,在水稻耐冷性育种及耐冷基因发掘研究中应加以利用。自然低温和冷水胁迫下水稻结实率与低温下发芽率呈显著或极显著正相关,而与死苗率呈显著负相关,即低温下发芽期耐冷性和芽期耐冷性强的水稻种质一般表现为较强的孕穗期耐冷性。认为低温下发芽率和芽期低温处理后的死苗率可以作为孕穗期耐冷性早期鉴定的间接指标。     

中国水稻微核心种质不同生育时期耐冷性鉴定及其相关分析

以204份中国水稻微核心种质为试验材料,进行了水稻发芽期、芽期、幼苗期、孕穗期等耐冷性鉴定及其相关性分析。结果表明,水稻各生育时期耐冷性在籼粳亚种间、各种质之间存在明显的差异。粳稻种质的耐冷性明显强于籼稻种质,但籼稻种质中也存在耐冷性较强的种质。高阳淀稻大红芒、肥东塘稻、木樨球、卫国、兴国、山酒谷、中花8号等粳稻种质和包选21号、红米三担白、寸谷糯、红谷等籼稻种质在水稻各生育时期均表现较强的耐冷性,在水稻耐冷性育种及耐冷基因发掘研究中应加以利用。自然低温和冷水胁迫下水稻结实率与低温下发芽率呈显著或极显著正相关,而与死苗率呈显著负相关,即低温下发芽期耐冷性和芽期耐冷性强的水稻种质一般表现为较强的孕穗期耐冷性。认为低温下发芽率和芽期低温处理后的死苗率可以作为孕穗期耐冷性早期鉴定的间接指标。     

Differentiation of Indica-Japonica rice revealed by insertion/deletion (InDel) fragments obtained from the comparative genomic study of DNA sequences between 93-11 (Indica) and Nipponbare (Japonica)

DNA polymorphisms from nucleotide insertion/deletions (InDels) in genomic sequences are the basis for developing InDel molecular markers.To validate the InDel primer pairs on the basis of the comparative genomic study on DNA sequences between an Indica rice 93-11 and a Japonica rice Nipponbare for identifying Indica and Japonica rice varieties and studying wild Oryza species,we studied 49 Indica,43 Japonica,and 24 wild rice accessions collected from ten Asian countries using 45 InDel primer pairs.Results indicated that of the 45 InDel primer pairs,41 can accurately identify Indica and Japonica rice varieties with a reliability of over 80%.The scatter plotting data of the principal component analysis (PCA) indicated that:(i) the InDel primer pairs can easily distinguish Indica from Japonica rice varieties,in addition to revealing their genetic differentiation;(ii) the AA-genome wild rice species showed a relatively close genetic relationship with the Indica rice varieties;and (iii)the non-AA genome wild rice species did not show evident differentiation into the Indica and Japonica types.It is concluded from the study that most of the InDel primer pairs obtained from DNA sequences of 93-11 and Nipponbare can be used for identifying lndica and Japonica rice varieties,and for studying genetic relationships of wild rice species,particularly in terms of the Indica-Japonica differentiation.     

Genetic manipulation of Japonica rice using the <Emphasis Type="Italic">OsBADH1</Emphasis> gene from Indica rice to improve salinity tolerance

Betaine aldehyde dehydrogenase (BADH) is a major oxidative enzyme that converts betaine aldehyde to glycine betaine (GB), an osmoprotectant compound in plants. Japonica rice (salt-sensitive) was genetically engineered to enhance salt tolerance by introducing the OsBADH1 gene from Indica rice (salt-tolerant), which is a GB accumulator. We produced transgenic rice plants overexpressing the modified OsBADH1 gene under the control of the maize ubiquitin promoter. The transgenic rice showed increased OsBADH1 gene expression and OsBADH1 enzyme production, resulting in the accumulation of GB. It also exhibited enhanced salt tolerance in immature and mature transgenic rice seedlings. The adverse effect of salt stress on seed germination, the growth of immature and mature seedlings, water status, and photosynthetic pigments was alleviated in transgenic seedlings.     

Differences between Indica and Japonica rice varieties in CO2 exchange rates in response to leaf nitrogen and temperature

Four Indica and five Japonica varieties of rice (Oryza sativa L.) were examined to elucidate their differences in photosynthetic activity and dark respiratory rate as influenced by leaf nitrogen levels and temperatures. The photosynthetic rates of single leaf showed correlations with total nitrogen and soluble protein contents in the leaves. Respiratory rate was also positively correlated with the leaf nitrogen content. When compared at the same level of leaf nitrogen or soluble protein content, the four Indica varieties and one of Japonica varieties, Tainung 67, which have some Indica genes derived from one of its parents, showed higher photosynthetic rates than the remaining four Japonica varieties. At the same photosynthetic rate, the Indica varieties showed lower respiratory rate than Japonica varieties. When the leaf temperature rose from 20°C to 30°C, the photosynthetic rate increased by 18 to 41%, whereas the respiratory rate increased by 100 to 150%. These increasing rates in response to temperature were higher in the Japonica than in the Indica varieties. In this respect, Tainung 67 showed the same behavior as of the other four Japonica varieties.Abbreviations 30/20 ratios the ratios of photosynthetic and respiratory rates at 30°C to those at 20°C     

Plant regeneration from protoplasts of Indica type rice and CMS rice

Cell suspensions were established from 12 rice genotypes including Indica type, Japonica type and cytoplasmic male sterile (cms) rice lines of both types. 133 green plants were regenerated from protoplasts isolated from an Indica type rice and 15 plants were obtained from a Japonica type cms rice. A cell suspension, from which protoplasts can be isolated (about 10⁶/ml) but from which cell division has not yet been induced, has been established from the most widely used Indica type cms rice which contains Wild Abortive (WA) cytoplasm.     

High-throughput single nucleotide polymorphism genotyping for breeding applications in rice using the BeadXpress platform

Multiplexed single nucleotide polymorphism (SNP) markers have the potential to increase the speed and cost-effectiveness of genotyping, provided that an optimal SNP density is used for each application. To test the efficiency of multiplexed SNP genotyping for diversity, mapping and breeding applications in rice (Oryza sativa L.), we designed seven GoldenGate VeraCode oligo pool assay (OPA) sets for the Illumina BeadXpress Reader. Validated markers from existing 1536 Illumina SNPs and 44?K Affymetrix SNP chips developed at Cornell University were used to select subsets of informative SNPs for different germplasm groups with even distribution across the genome. A 96-plex OPA was developed for quality control purposes and for assigning a sample into one of the five O. sativa population subgroups. Six 384-plex OPAs were designed for genetic diversity analysis, DNA fingerprinting, and to have evenly-spaced polymorphic markers for quantitative trait locus (QTL) mapping and background selection for crosses between different germplasm pools in rice: Indica/Indica, Indica/Japonica, Japonica/Japonica, Indica/O. rufipogon, and Japonica/O. rufipogon. After testing on a diverse set of rice varieties, two of the SNP sets were re-designed by replacing poor-performing SNPs. Pilot studies were successfully performed for diversity analysis, QTL mapping, marker-assisted backcrossing, and developing specialized genetic stocks, demonstrating that 384-plex SNP genotyping on the BeadXpress platform is a robust and efficient method for marker genotyping in rice.     

Linkage analysis of the nuclear homologues of mitochondrial plasmid-like DNAs in rice.

A genetical study on the nucleotide sequences of the nuclear DNAs which share homology with rice mitochondrial plasmid-like DNAs, B1, B2, B3 and B4 was carried out. Restriction fragments of the nuclear DNAs hybridized with these plasmid-like DNAs showed polymorphisms in their length between Indica and Japonica rice cultivars. The hybridized signals found specifically in Indica or Japonica cultivars segregated in the F2 population derived from a cross between these two subspecies. The observed ratio of the nuclear homologues in the F2 population demonstrated that they were transmitted according to the Mendelian inheritance. The co-segregation of homologues was examined and the linkage was detected between the B1-nuclear homologue of Japonica and the B4-nuclear homologue of Indica, and also between the nuclear homologues of B2 and B3 of Indica. The linkage between the B1-nuclear homologue of Japonica and the B4-nuclear homologue of Indica was conserved in the different rice cultivars.     

Genomic paleontology provides evidence for two distinct origins of Asian rice (<Emphasis Type="Italic">Oryza sativa </Emphasis>L.)

The origin of rice domestication has been the subject of debate for several decades. We have compared the transpositional history of 110 LTR retrotransposons in the genomes of two rice varieties, Nipponbare (Japonica type) and 93-11 (Indica type) whose complete sequences have recently been released. Using a genomic paleontology approach, we estimate that these two genomes diverged from one another at least 200,000 years ago, i.e., at a time which is clearly older than the date of domestication of the crop (10,000 years ago, during the late Neolithic). In addition, we complement and confirm this first in silico analysis with a survey of insertion polymorphisms in a wide range of traditional rice varieties of both Indica and Japonica types. These experimental data provide additional evidence for the proposal that Indica and Japonica rice arose from two independent domestication events in Asia.Electronic Supplementary Material Supplementary material is available in the online version of this article at Communicated by M.-A. Grandbastien     

Improved frequency of transformation in rice and maize by treatment of immature embryos with centrifugation and heat prior to infection with Agrobacterium tumefaciens

The efficiency of transformation was improved by treating immature embryos with heat and centrifugation before infection with Agrobacterium tumefaciens in rice and maize. Because the effects were detected both in the levels of transgene expression after co-cultivation and in the number of independent transgenic plants obtained per embryo, conditions were first optimized based on the transgene expression, and then transformants were produced. The optimal conditions varied considerably depending on species and genotypes, but reasonably good parameters were identified for Japonica rice, Indica rice or maize. As a general tendency, the effect of centrifugation was greater than that of heat in Japonica rice, whereas that of heat was greater than that of centrifugation in Indica rice and maize A188, and the combination of the treatments was the most effective in all of the genotypes tested. The frequency of transformation was improved several fold in rice and maize. In addition, transformation of certain genotypes of maize, which were not transformable before, and transformation of maize with a less efficient vector, which could not transform maize before, became possible by these pre-treatments. In the highest case, 18 independent transgenic plants were obtained from a single immature embryo of Japonica rice. Although nothing is known about the mechanism, these pre-treatments seemed to render cells of rice and maize more competent for transformation mediated by A. tumefaciens.     

Relative contributions of photochemical and non-photochemical routes to excitation energy dissipation in rice and barley illuminated at a chilling temperature

The mechanistic basis for differential sensitivities to chilling-induced photoinhibition among two rice ( Oryza sativa L.) cultivars (an Indica and a Japonica type) and one barley cultivar ( Hordeum vulgare L. cv. Albori) was examined. When leaf segments were exposed to moderate illumination at 4°C, a sustained decrease in the photochemical efficiency of photosystem (PS) II measured as the ratio of variable to maximal fluorescence (F_v/F_m) was observed for several hours. An analysis of fluorescence quenching revealed a sudden drop in PSII-driven electron transport rate (ETR) and a rapid rise in the reduction state of the primary electron acceptor Q_A upon exposure to chilling in moderate light. There was no appreciable difference in the level of non-photochemical quenching (NPQ) nor in the xanthophyll cycle activity between Japonica rice and barley. However, barley was capable of sustaining a higher ETR, thereby keeping a lower reduction state of Q_A throughout the chilling for 6 h. The Indica rice was characterized by the lowest ability to develop the xanthophyll cycle-associated NPQ, particularly the fast relaxing NPQ component (qf), accompanied by the highest reduction state of Q_A and photoinhibitory quenching (qI). It is concluded that the lower susceptibility of barley to chilling-induced photoinhibition than Japonica rice is attributable to its higher potential to dissipate excess light energy via a photochemical mechanism, whereas Indica rice is more sensitive to photoinhibition at a chilling temperature than Japonica rice, due primarily to its lower capacity to develop an efficient NPQ pathway.     

长江三角洲主要超级稻CH4排放特征及其与植株生长特性的关系

采用盆栽试验研究了长江三角洲14个主要超级稻品种(6个粳型超级稻和8个籼型杂交超级稻)CH₄排放特征及其与植株生长特性之间的关系.结果表明: 粳型和籼型超级稻全生育期CH₄排放均呈双峰模式,排放峰值分别出现在分蘖盛期和孕穗期.粳型超级稻的平均CH₄排放总量比籼型超级稻高37.6%(P<0.01),品种间排放差异主要出现在生长后期.虽然两种类型超级稻的CH₄排放总量均与最大叶面积呈显著正相关,但CH₄排放与其他生长特性的关系因品种类型而异.在株高上,粳型超级稻CH₄排放总量与株高呈显著正相关,而籼型超级稻的相关不显著.在生产力上,籼型超级稻CH₄排放总量与其总生物量、籽粒产量和收获指数呈显著负相关,而粳型超级稻的相关不显著.籼型超级稻CH₄排放量低主要是由于其根系生物量显著高于粳型超级稻.     

长江三角洲主要超级稻CH4排放特征及其与植株生长特性的关系

采用盆栽试验研究了长江三角洲14个主要超级稻品种(6个粳型超级稻和8个籼型杂交超级稻)CH₄排放特征及其与植株生长特性之间的关系.结果表明: 粳型和籼型超级稻全生育期CH₄排放均呈双峰模式,排放峰值分别出现在分蘖盛期和孕穗期.粳型超级稻的平均CH₄排放总量比籼型超级稻高37.6%(P<0.01),品种间排放差异主要出现在生长后期.虽然两种类型超级稻的CH₄排放总量均与最大叶面积呈显著正相关,但CH₄排放与其他生长特性的关系因品种类型而异.在株高上,粳型超级稻CH₄排放总量与株高呈显著正相关,而籼型超级稻的相关不显著.在生产力上,籼型超级稻CH₄排放总量与其总生物量、籽粒产量和收获指数呈显著负相关,而粳型超级稻的相关不显著.籼型超级稻CH₄排放量低主要是由于其根系生物量显著高于粳型超级稻.     

Natural variation in the promoter of OsHMA3 contributes to differential grain cadmium accumulation between Indica and Japonica rice

Rice is a major source of cadmium(Cd) intake for Asian people. Indica rice usually accumulates more Cd in shoots and grains than Japonica rice. However, underlying genetic bases for differential Cd accumulation between Indica and Japonica rice are still unknown. In this study, we cloned a quantitative trait locus(QTL) grain Cd concentration on chromosome 7(GCC7) responsible for differential grain Cd accumulation between two rice varieties by performing QTL analysis and map-based cloning. We found that the two GCC7 alleles, GCC7~(PA64s) and GCC7~(93-11), had different promoter activity of OsHMA3,leading to different OsHMA3 expression and different shoot and grain Cd concentrations. By analyzing the distribution of different haplotypes of GCC7 among diverse rice accessions, we discovered that the high and low Cd accumulation alleles, namely GCC7~(93-11) and GCC7~(PA64s), were preferentially distributed in Indica and Japonica rice,respectively. We further showed that the GCC7~(PA64s)allele can be used to replace the GCC7~(93-11) allele in the super cultivar 93-11 to reduce grain Cd concentration without adverse effect on agronomic traits. Our results thus reveal that the QTL GCC7 with sequence variation in the OsHMA3 promoter is an important determinant controlling differential grain Cd accumulation between Indica and Japonica rice.     

盐胁迫下不同水稻种质形态指标与耐盐性的相关分析

选用中国、韩国和国际水稻研究所(IRRI)不同耐盐能力的籼、粳、爪哇稻16份为材料进行芽期和苗期试验。随着NaCl浓度增加,种子开始发芽的时间推迟、发芽过程延长、发芽率降低;品种的发芽率能有效地指示其芽期耐盐能力。NaCl浓度对许多苗期形态指标有显影响,其中叶片盐害指数能反映品种的苗期耐盐能力;随着NaCl处理时间的增长,叶片盐害指数与NaCl浓度间的相关性越来越大。同一品种在芽期的耐盐能力和苗期表现不一致,两的相关系数很低。     

重复DNA顺序pRRD9在稻属中的拷贝数测定

本文应用狭缝印渍杂交方法,把水稻基因组总DNA和含水稻中度重复顺序片段的质粒(pRRD9)DNA分别转移到尼龙膜上形成狭缝印渍、然后用~(32)P标记的 pRRD9插入片段进行杂交、根据各狭缝印渍的放射性强度,测定水稻(Oryza)一些栽培种和野生种基因组中重复DNA顺序的拷贝数,并就拷贝数与水稻进化关系及基因组型的联系进行讨论.     

镉对水稻种子萌发的影响

以不同类型的319个水稻品种为研究对象,研究了10 mg·L^-1 Cd²⁺处理对水稻种子萌发的影响.结果表明:Cd²⁺对种子发芽率影响较小,对根系生长的影响显著,且大于对芽生长的影响;不同类型水稻种子萌发对Cd的响应差异较大,敏感顺序为粳稻>籼稻>杂交稻;两系不育系根系长度和根系数量受Cd的抑制程度显著高于三系.应用快速聚类方法,可以将参试品种划分为耐受型、中间型和敏感型3种不同的敏感类型.     

Changes in sugars during rice seed desiccation

The correlation between desiccation tolerance and soluble sugars was investigated in seeds of a number of rice cultivars belonging to the Asian rice Oryza sativa L. They were dried or ultradried to various low moisture content and then imbibed for germination testing. Few or no changes on germination percentage and vigor index were found in Indian rice seeds even after their moisture content fell to 3.5%, indicating that Indian rice exhibited a strong desiccation tolerance. On the contrary, Japonica rice seed germination percentage rapidly decreased, after their moisture content fell to 4.5%. The capacity for desiccation tolerance in Japonica (cv. Chunjiang 15) and Indian (cv. Zhongzu 1) developing seeds increased on 23–40 and 15–25 days after pollination, respectively. Though the level of monosaccharides declined, the content of sucrose has increased during desiccation. These results suggest that desiccation tolerance might be associated with the increase in seed viability and the changes in sugar level, and that raffinose could be capable of contributing to the desiccation tolerance to ultradrying. Published in Russian in Fiziologiya Rastenii, 2006, Vol. 53, No. 2, pp. 220–226. The text was submitted by the authors in English.     

Development and application of a set of breeder-friendly SNP markers for genetic analyses and molecular breeding of rice (Oryza sativa L.)

Single nucleotide polymorphisms (SNPs) are the most abundant DNA markers in plant genomes. In this study, based on 54,465 SNPs between the genomes of two Indica varieties, Minghui 63 (MH63) and Zhenshan 97 (ZS97) and additional 20,705 SNPs between the MH63 and Nipponbare genomes, we identified and confirmed 1,633 well-distributed SNPs by PCR and Sanger sequencing. From these, a set of 372 SNPs were further selected to analyze the patterns of genetic diversity in 300 representative rice inbred lines from 22 rice growing countries worldwide. Using this set of SNPs, we were able to uncover the well-known Indica-Japonica subspecific differentiation and geographic differentiations within Indica and Japonica. Furthermore, our SNP results revealed some common and contrasting patterns of the haplotype diversity along different rice chromosomes in the Indica and Japonica accessions, which suggest different evolutionary forces possibly acting in specific regions of the rice genome during domestication and evolution of rice. Our results demonstrated that this set of SNPs can be used as anchor SNPs for large scale genotyping in rice molecular breeding research involving Indica-Japonica and Indica-Indica crosses.     

水稻籽粒直链淀粉含量的生态模型研究

在中国、日本和泰国不同生态环境下进行了多品种籼稻和粳稻的种植试验,通过分析水稻籽粒直链淀粉含量与纬度、海拔、温度、太阳辐射等气候生态因子的相互关系,确立了影响水稻籽粒直链淀粉积累的主要气候因子函数,并使用权重系数进一步修订各个气候生态因子对籽粒直链淀粉的作用,构建出基于生态效应(综合气候因子函数)的水稻籽粒直链淀粉含量预测模型.利用不同年份、不同生态点和不同品种类型的试验资料对所建模型进行了检验,籼稻和粳稻籽粒直链淀粉含量的预测误差(RMSE)平均分别为0.4%和0.5%;籼稻和粳稻种植区的预测误差(RMSE)平均为0.39%和0.50%,表明模型具有较好的预测性和实用性.