云南栽培稻种SSR 遗传多样性比较

采用64个SSR标记对96份云南水稻(Oryz a sativa)地方品种和选育品种的遗传多样性进行比较分析。结果发现64个标记都具有多态性, 共检测到741个等位基因, 每个多态性位点检测到的等位基因数为2-29个, 平均11.57个; Nei基因多样性指数(He)范围在0.345(RM321)-0.932(RM1)之间, 平均为0.56。水稻品种的遗传多样性并非按地理位置均匀分布, 而是在相 似系数为0.17的水平上明显分为2个不同类群, 即籼稻类群和粳稻类群, 且籼粳亚种间的SSR多样性差异不明显, 籼稻平均等位基因数(Ap)和Nei基因多样性指数(Ap=10.6, He=0.46)与粳稻品种(Ap=10.7, He=0.48)十分接近, 可能与这些品种间存在一定频率的基因交流有关。糯稻和非糯稻在籼稻群和粳稻群中都有表现, 没有特别的分布规律。云南栽培稻选育品种与地方稻亲缘关系较近, 其遗传基础可能来源于云南水稻地方品种。本研究结果表明, SSR标记能较好地区分云南栽培稻品种, 且云南水稻地方品种遗传多样性丰富, 存在大量的优质性状可供育种实践选择。     

云南栽培稻种SSR遗传多样性比较

采用64个SSR标记对96份云南水稻（Oryza sativa）地方品种和选育品种的遗传多样性进行比较分析。结果发现64个标记都具有多态性,共检测到741个等位基因,每个多态性位点检测到的等位基因数为2—29个,平均11．57个：Nei基因多样性指数（He）范围在0．345（RM321）-0．932（RM1）之间,平均为0．56。水稻品种的遗传多样性并非按地理位置均匀分布,而是在相似系数为0．17的水平上明显分为2个不同类群,即籼稻类群和粳稻类群,且籼粳亚种间的SSR多样性差异不明显,籼稻平均等位基因数（Ap）和Nei基因多样性指数（Ap=10．6,He=0．46）与粳稻品种（Ap=10．7,He=0．48）十分接近,可能与这些品种间存在一定频率的基因交流有关。糯稻和非糯稻在籼稻群和粳稻群中都有表现,没有特别的分布规律。云南栽培稻选育品种与地方稻亲缘关系较近,其遗传基础可能来源于云南水稻地方品种。本研究结果表明,SSR标记能较好地区分云南栽培稻品种,且云南水稻地方品种遗传多样性丰富,存在大量的优质性状可供育种实践选择。     

香稻资源遗传多样性的比较

利用60个水稻SSR标记, 对来自国内外的370份香稻材料的遗传多样性进行了比较分析。结果共检测到361个等位基因, 每个位点的等位基因变幅为2~10个, 平均Nei基因多样性指数(He)为0.663, 变幅为0.104(RM308)~0.885(RM2634)。籼粳亚种间的遗传多样性具有明显差异, 籼稻的等位基因数和Nei基因多样性指数均高于粳稻。地方品种的遗传多样性高于选育品种, 选育品种等位基因数仅为地方品种的86.5%。分子方差分析表明, 香稻材料中总变异的43.08%是由于亚种间的遗传差异引起的。不同稻区的遗传分化程度总体介于1.69%~14.40%之间。其中, 华南与西南、华中与西南地方品种间遗传差异的分化程度达显著水平。聚类分析将参试材料明显分为籼粳两大类, 同时地域相同(稻区)、相邻省份的香稻材料基本归为同一类群。     

Genetic structure and differentiation of <Emphasis Type="Italic">Oryza sativa</Emphasis> L. in China revealed by microsatellites

China is one of the largest centers of genetic diversity of Oryza sativa L. in the world. Using a genetically representative primary core collection of 3,024 rice landraces in China, we analyzed the genetic structure and intraspecific differentiation of O. sativa, and the directional evolution of SSR. The genetic structure was investigated by model-based structure analysis and construction of neighbor-joining phylogenetic tree. Comparison between genetic structure and predefined populations according to Ting’s taxonomic system revealed a hierarchical genetic structure: two distinct subspecies, each with three ecotypes and different numbers of geo-ecogroups within each ecotype. Two subspecies evidently resulted from adaptation to different environments. The different cropping systems imposed on the subspecies led to further differentiation, but the variation within each subspecies resulted from different causes. Indica, under tropical-like or lowland-like environments, exhibited clear differentiation among seasonal ecotypes, but not among soil-watery ecotypes; and japonica showed clear differences between soil water regime ecotypes, but not among seasonal ecotypes. Chinese cultivated rice took on evident directional evolution in microsatellite allele size at several aspects, such as subspecies and geographical populations. Japonica has smaller allele sizes than indica, and this may partly be the result of their different domestication times. Allele size was also negatively correlated with latitude and altitude, and this may be interpreted by different mutation rates, selection pressures, and population size effects under different environments and cropping systems.     

云南地方稻waxy基因序列多样性分析

利用特异引物Wx-F/AG-2对来源于云南省16个州市64个县的252份地方稻种waxy基因中含有微卫星序列(CT)n和第一内含子的序列进行PCR扩增并测序。结果表明在268个碱基的序列内检测到4个变异位点:第一内含子上游56位处(CT)n存在(CT)10、(CT)11、(CT)12、(CT)14、(CT)16、(CT)17、(CT)18、(CT)19、(CT)20、(CT)21等10种变异;(CT)11、(CT)18、(CT)17、(CT)12、(CT)10等5种单倍型是云南优势类型,合计占供试材料的92.85%;籼稻以(CT)10、(CT)11、(CT)12为主,而粳稻以(CT)11、(CT)12、(CT)17和(CT)18为主;第一内含子+1位存在G/T变异,81.75%品种是G,T只出现在(CT)16、(CT)17、(CT)18和(CT)20的品种中,其频率在籼稻中为13.48%,粳稻20.86%,水稻16.17%,陆稻22.35%,粘稻10.47%,糯稻42.62%。+86-88位存在ATA/GTA/A--3种变异;+128位处存在(AATT)5和(AATT)6 2种变异。根据这4个变异位点,可将252个云南地方稻种归为16种单倍型,其中Wx4(32.54%)、Wx9(13.89%)、Wx12(12.7%)、Wx5(12.3%)、Wx1(8.33%)、Wx11(7.94%)是主要类型,合计87.7%,其他类型频率较低。籼/粳亚种、水/陆稻和粘/糯中存在单倍型种类和单倍型频率两方面的差异,籼稻/粳稻、水/陆稻和粘/糯稻各亚种或生态型均有独享的单倍型,共享单倍型频率也存在差异,表明亚种间或生态型间发生了一定的遗传分化。单倍型地理分布分析表明,临沧、普洱单倍型种类最丰富,以之为中心向外扩展,单倍型种类有减少的趋势,第一内含子+1位的T主要分布在临沧、普洱、西双版纳、德宏等南部地区。本研究揭示了云南地方稻种群体waxy基因的变异和分布特点。     

云南地方稻核心种质耐低磷特性研究

1引言磷是作物的必需性营养元素,人类将面临农业可持续发展与磷素资源严重短缺的矛盾[17].土壤普查结果表明,全国有59%以上的土壤缺磷[1].为了提高作物产量,生产中通过施用磷肥来解决土壤缺磷的问题.由于磷肥利用率低,不仅增加生产成本,还带来资源短缺、环境污染及食品安全等诸多问题[21,26].发掘水稻利用磷的内在潜力,培育磷高效利用新品种,可减少磷的施用量.近年来,野生或地方稻绿色基因发掘及改良进展显著,如资源高效利用[22~24]、高产基因[3,20,27]和抗性基因[2,13]等,利用植物基因型间磷元素利用效率的差异,筛选和培育磷高效基因型作物…     

Molecular evaluation of genetic diversity and association studies in rice (<Emphasis Type="BoldItalic">Oryza sativa</Emphasis> L.)

In the present study, we tested rice genotypes that included un(der)exploited landraces of Tamil Nadu along with indica and japonica test cultivars to ascertain their genetic diversity structure. Highly polymorphic microsatellite markers were used for generating marker segregation data. A novel measure, allele discrimination index, was used to determine subpopulation differentiation power of each marker. Phenotypic data were collected for yield and component traits. Pattern of molecular differentiation separated indica and japonica genotypes; indica genotypes had two subpopulations within. Landraces were found to have indica genome, but formed a separate subgroup with low linkage disequilibrium. The landraces further separated into distinct group in both hierarchical clustering analysis using neighbour-joining method as well as in the model based population structure analysis. Japonica and the remaining indica cultivars formed two other distinct groups. Linkage disequilibrium observed in the whole population was considerably reduced in subpopulations. Low linkage disequilibrium of landforms suggests their narrow adaptation in local geographical niche. Many population specific alleles could be identified particularly for japonica cultivars and landraces. Association analysis revealed nine marker-trait associations with three agronomic traits, of which 67% were previously reported. Although the testing landraces together with known cultivars had permitted genomewide association mapping, the experiment offers scope to study more landraces collected from the entire geographical region for drawing more reliable information.     

Genetic Variation and Indica Japonica Differentiation in Yunnan Indigenous Rice

Yunnan, in Southwest China, has long been recognized as part of a center of diversity for Asia cultivated rice (Oryza sativa L. ). The authors surveyed DNA restriction fragment length polymorphisms (RFLPs) in a sample of 87 accessions from Yunnan indigenous rice with 7 single copy probes. The results ihdicated that both indica and japonica rice are genetically highly diverse. The number of alleles and the level of genic diversity in japonica rice were higher than those in indica rice. The results also showed that indica and japonica rices were clearly differentiated and the extent of differentiation varies with chromosomal regions as represented by the RFLP markers. Authors' results appeared to be in favor of the diphyletic hypothesis concerning the origin of cultivated rice.     

Migration, isolation and hybridization in island crop populations: the case of Madagascar rice

Understanding how crop species spread and are introduced to new areas provides insights into the nature of species range expansions. The domesticated species Oryza sativa or Asian rice is one of the key domesticated crop species in the world. The island of Madagascar off the coast of East Africa was one of the last major Old World areas of introduction of rice after the domestication of this crop species and before extensive historical global trade in this crop. Asian rice was introduced in Madagascar from India, the Malay Peninsula and Indonesia approximately 800-1400 years ago. Studies of domestication traits characteristic of the two independently domesticated Asian rice subspecies, indica and tropical japonica, suggest two major waves of migrations into Madagascar. A population genetic analysis of rice in Madagascar using sequence data from 53 gene fragments provided insights into the dynamics of island founder events during the expansion of a crop species' geographic range and introduction to novel agro-ecological environments. We observed a significant decrease in genetic diversity in rice from Madagascar when compared to those in Asia, likely the result of a bottleneck on the island. We also found a high frequency of a unique indica type in Madagascar that shows clear population differentiation from most of the sampled Asian landraces, as well as differential exchange of alleles between Asia and Madagascar populations of the tropical japonica subspecies. Finally, despite partial reproductive isolation between japonica and indica, there was evidence of indica/japonica recombination resulting from their hybridization on the island.     

SSR标记揭示的云南地方稻品种遗传多样性及其保育意义

为了探索水稻(Oryza sativa L.)地方品种的遗传多样性及其有效保育方法,对采自云南省17个村寨的82个水稻地方品种和3个国际常用的典型籼稻和粳稻品种进行了微卫星(SSR)分子标记的分析.利用19对SSR引物在85个水稻品种中共扩增出了83个基因型,其分子量变异在100～500 bp之间.基于各品种SSR基因型遗传相似系数聚类分析而获得的UPGMA树状图表明各水稻品种之间存在较大的遗传多样性,其相似系数变异在0.15～0.90之间.但这些地方品种的遗传多样性并非呈均等的地理分布.这85个水稻品种在相似系数为0.52之处分为二组,其中一组包括几乎所有的籼稻品种,而另一组包括全部的粳稻品种,表明SSR标记能很好揭示水稻籼-粳分化.同时,有些来自不同采集地的同名品种表现出一定的遗传差异,说明同名异物的现象存在.云南水稻地方品种具有丰富的遗传多样性,对其有效保育十分重要和迫切,但只有根据遗传多样性的水平和分布特点,采用正确的保育对策和取样方法才能确保对云南水稻地方品种的有效保育.结果进一步表明,选用适当的微卫星引物,可以为准确鉴定籼稻和粳稻品种及研究其进化规律提供有效的分子标记方法,并有利于有目标的水稻遗传资源保育和育种创新.     

SSR标记揭示的云南地方稻品种遗传多样性及其保育意义

为了探索水稻(Oryza　sativa　L.)地方品种的遗传多样性及其有效保育方法,对采自云南省17个村寨的82个水稻地方品种和3个国际常用的典型籼稻和粳稻品种进行了微卫星(SSR)分子标记的分析。利用19对SSR引物在85个水稻品种中共扩增出了83个基因型,其分子量变异在100～500　bp之间。基于各品种SSR基因型遗传相似系数聚类分析而获得的UPGMA树状图表明各水稻品种之间存在较大的遗传多样性,其相似系数变异在0.15～0.90之间。但这些地方品种的遗传多样性并非呈均等的地理分布。这85个水稻品种在相似系数为0.52之处分为二组,其中一组包括几乎所有的籼稻品种,而另一组包括全部的粳稻品种,表明SSR标记能很好揭示水稻籼-粳分化。同时,有些来自不同采集地的同名品种表现出一定的遗传差异,说明同名异物的现象存在。云南水稻地方品种具有丰富的遗传多样性,对其有效保育十分重要和迫切,　但只有根据遗传多样性的水平和分布特点,采用正确的保育对策和取样方法才能确保对云南水稻地方品种的有效保育。结果进一步表明,选用适当的微卫星引物,可以为准确鉴定籼稻和粳稻品种及研究其进化规律提供有效的分子标记方法,并有利于有目标的水稻遗传资源保育和育种创新。     

Genetic diversity analysis of traditional and improved Indonesian rice (Oryza sativa L.) germplasm using microsatellite markers

The archipelago of Indonesia has a long history of rice production across a broad range of rice-growing environments resulting in a diverse array of local Indonesian rice varieties. Although some have been incorporated into modern breeding programs, the vast majority of these landraces remain untapped. To better understand this rich source of genetic diversity we have characterized 330 rice accessions, including 246 Indonesian landraces and 63 Indonesian improved cultivars, using 30 fluorescently-labeled microsatellite markers. The landraces were selected across 21 provinces and include representatives of the classical subpopulations of cere, bulu, and gundil rices. A total of 394 alleles were detected at the 30 simple sequence repeat loci, with an average number of 13 alleles per locus across all accessions, and an average polymorphism information content value of 0.66. Genetic diversity analysis characterized the Indonesian landraces as 68% indica and 32% tropical japonica, with an indica gene diversity of 0.53 and a tropical japonica gene diversity of 0.56, and a Fst of 0.38 between the two groups. All of the improved varieties sampled were indica, and had an average gene diversity of 0.46. A set of high quality Indonesian varieties, including Rojolele, formed a separate cluster within the tropical japonicas. This germplasm presents a valuable source of diversity for future breeding and association mapping efforts.     

Genotypic and phenotypic characterization of genetic differentiation and diversity in the USDA rice mini-core collection

A rice mini-core collection consisting of 217 accessions has been developed to represent the USDA core and whole collections that include 1,794 and 18,709 accessions, respectively. To improve the efficiency of mining valuable genes and broadening the genetic diversity in breeding, genetic structure and diversity were analyzed using both genotypic (128 molecular markers) and phenotypic (14 numerical traits) data. This mini-core had 13.5 alleles per locus, which is the most among the reported germplasm collections of rice. Similarly, polymorphic information content (PIC) value was 0.71 in the mini-core which is the highest with one exception. The high genetic diversity in the mini-core suggests there is a good possibility of mining genes of interest and selecting parents which will improve food production and quality. A model-based clustering analysis resulted in lowland rice including three groups, aus (39 accessions), indica (71) and their admixtures (5), upland rice including temperate japonica (32), tropical japonica (40), aromatic (6) and their admixtures (12) and wild rice (12) including glaberrima and four other species of Oryza. Group differentiation was analyzed using both genotypic distance Fst from 128 molecular markers and phenotypic (Mahalanobis) distance D(2) from 14 traits. Both dendrograms built by Fst and D(2) reached similar-differentiative relationship among these genetic groups, and the correlation coefficient showed high value 0.85 between Fst matrix and D(2) matrix. The information of genetic and phenotypic differentiation could be helpful for the association mapping of genes of interest. Analysis of genotypic and phenotypic diversity based on genetic structure would facilitate parent selection for broadening genetic base of modern rice cultivars via breeding effort.     

Microsatellite diversity within Oryza sativa with emphasis on indica-japonica divergence

The molecular evolution of cultivated rice Oryza sativa L. has long been a subject of rice evolutionists. To investigate genetic diversity within and differentiation between the indica and japonica subspecies, 22 accessions of indica and 35 of japonica rice were examined by five microsatellite loci from each chromosome totalling 60 loci. Mean gene diversity value in the indica rice (H=0.678) was 1.18 times larger than in the japonica rice (H=0.574). Taking the sampling effect into consideration, average allele number in the indica rice was 1.40 times higher than that in the japonica rice (14.6 vs 10.4 per variety). Chromosome-based comparisons revealed that nine chromosomes (1, 2, 3, 4, 5, 8, 9, 10 and 11) harboured higher levels of genetic diversity within the indica rice than the japonica rice. An overall estimate of F(ST) was 0.084-0.158, indicating that the differentiation is moderate and 8.4-15.8% of the total genetic variation resided between the indica and japonica groups. Our chromosome-based comparisons further suggested that the extent of the indica-japonica differentiation varied substantially, ranging from 7.62% in chromosome 3 to 28.72% in chromosome 1. Cluster analyses found that most varieties formed merely two clusters for the indica and japonica varieties, in which two japonica varieties and five indica varieties were included in the counterpart clusters, respectively. The 12 chromosome-based trees further showed that 57 rice varieties cannot be clearly clustered together into either the indica or japonica groups, but displayed relatively different clustering patterns. The results suggest that the process of indica japonica differentiation may have proceeded through an extensive contribution by the alleles of the majority in the rice genome.     

Genetic structure and diversity in Oryza sativa L

The population structure of domesticated species is influenced by the natural history of the populations of predomesticated ancestors, as well as by the breeding system and complexity of the breeding practices exercised by humans. Within Oryza sativa, there is an ancient and well-established divergence between the two major subspecies, indica and japonica, but finer levels of genetic structure are suggested by the breeding history. In this study, a sample of 234 accessions of rice was genotyped at 169 nuclear SSRs and two chloroplast loci. The data were analyzed to resolve the genetic structure and to interpret the evolutionary relationships between groups. Five distinct groups were detected, corresponding to indica, aus, aromatic, temperate japonica, and tropical japonica rices. Nuclear and chloroplast data support a closer evolutionary relationship between the indica and the aus and among the tropical japonica, temperate japonica, and aromatic groups. Group differences can be explained through contrasting demographic histories. With the availability of rice genome sequence, coupled with a large collection of publicly available genetic resources, it is of interest to develop a population-based framework for the molecular analysis of diversity in O. sativa.     

Molecular diversity and multilocus organization of the parental lines used in the International Rice Molecular Breeding Program

One hundred and ninety three parental lines obtained from 26 countries for an international rice molecular breeding program were evaluated using 101 well-distributed simple sequence repeat (SSR) markers. An overall genetic diversity of 0.68 and an average of 6.3 alleles per locus were revealed, indicating a high level of genetic variation in these lines. Cluster analysis of the 193 accessions showed three major groups and nine subgroups. Group I corresponded to the classical indica subspecies, whereas groups II and III belong to the japonica subspecies. Indica and japonica differentiation accounted for only 6.5% of the total variation in the entire sample and 93.5% was due to within-subspecies diversity. Differentiation among eco-geographic regions accounted for 24% of the diversity within the subspecies. Larger amounts of the eco-geographical differentiation were resolved within japonica than within indica. The largest indica-japonica differentiation based on the single locus level was detected by markers on chromosomes 9 and 12, while the smallest differentiation was detected by markers on chromosomes 4 and 8. Furthermore, genetic differences at the single-locus and two-locus levels, as well as components due to allelic and gametic differentiation, were revealed between indica and japonica and among the main geographic regions. The multilocus analysis in genetic diversity showed a higher proportion of variation caused by predominant non-random associations of different loci within and among the classified subspecies and geographic subdivisions. The results suggest that selection for eco-geographical adaptation on multilocus associations was largely responsible for the maintenance of the extensive variation in the primary gene pool of rice.Communicated by Q. ZhangS.B. Yu and W.J. Xu contributed equally to the work     

Genetic diversity and origin of weedy rice (Oryza sativa f. spontanea) populations found in North-eastern China revealed by simple sequence repeat (SSR) markers

BACKGROUND AND AIMS: Weedy rice (Oryza sativa f. spontanea) is one of the most notorious weeds occurring in rice-planting areas worldwide. The objectives of this study are to determine the genetic diversity and differentiation of weedy rice populations from Liaoning Province in North-eastern China and to explore the possible origin of these weedy populations by comparing their genetic relationships with rice varieties (O. sativa) and wild rice (O. rufipogon) from different sources. METHODS: Simple sequence repeat (SSR) markers were used to estimate the genetic diversity of 30 weedy rice populations from Liaoning, each containing about 30 individuals, selected rice varieties and wild O. rufipogon. Genetic differentiation and the relationships of weedy rice populations were analysed using cluster analysis (UPGMA) and principle component analysis (PCA). KEY RESULTS: The overall genetic diversity of weedy rice populations from Liaoning was relatively high (H(e) = 0.313, I = 0.572), with about 35 % of the genetic variation found among regions. The Liaoning weedy rice populations were closely related to rice varieties from Liaoning and japonica varieties from other regions but distantly related to indica rice varieties and wild O. rufipogon. CONCLUSIONS: Weedy rice populations from Liaoning are considerably variable genetically and most probably originated from Liaoning rice varieties by mutation and intervarietal hybrids. Recent changes in farming practices and cultivation methods along with less weed management may have promoted the re-emergence and divergence of weedy rice in North-eastern China.     

元阳3个长期连续栽培水稻地方品种内部遗传异质性分析

水稻地方品种是稻种资源的重要组成部分,遗传多样性十分丰富,具有推广改良品种所缺少或没有的优质种质,是水稻育种和稻种起源、进化研究不可缺少的过渡材料。目前,对水稻地方品种间遗传多样性研究较多,而对其内部异质性研究甚微。本研究用24对微卫星(SSR)引物对云南元阳梯田3个栽种历史悠久的水稻地方品种的内部遗传异质性进行了分析。共检测出117个等位基因,香农指数为红脚老粳居群(0.5911)>白脚老粳A居群(0.4875)>月亮谷居群(0.3070)。结果显示:3个地方品种的内部遗传异质性丰富,且遗传异质性主要得益于个体间,而非居群间。     

Elemental Content in Brown Rice by Inductively Coupled Plasma Atomic Emission Spectroscopy Reveals the Evolution of Asian Cultivated Rice

The phylogenetic relationship for classification traits and eight mineral elements in brown rice (Oryza sativa L.) from Yunnan Province in China was carried out using microwave assisted digestion followed by inductively coupled plasma atomic emission spectroscopy, and the analytical procedures were carefully controlled and validated. In general, the results show that the mean levels of K, Ca, Mg, Fe and Cu in brown rice for 789 accessions of rice landraces was distinctly lower than that of improved cultivars. They further demonstrate that Ca plays an important role in the differentiation of subspecies indica-japonica, especially to enhance adaptation of cold stress, and that five mineral elements in brown rice enhance the eurytopicity from landrace to improved cultivar. Hierarchical cluster analysis, using average linkage from SPSS software based on eight mineral elements in brown rice, showed that Yunnan rice could be grouped into rice landrace and improved cultivar, with the rice landrace being further clustered into five subgroups, and that, interestingly, purple rice does not cluster with either of the groups. Our present data confirm that indica is the closest relative of late rice and white rice, and that they constitute rice landraces together, whereas japonica is the closest relatives of non-nuda, early-mid and glutinous rice. It is further shown that japonica, non-nuda, early-mid, glutinous, white and red rice might be more primitive than indica, nuda, late, non-glutinous and purple rice, respectively.