共查询到20条相似文献,搜索用时 31 毫秒
1.
Sweeney MT Thomson MJ Cho YG Park YJ Williamson SH Bustamante CD McCouch SR 《PLoS genetics》2007,3(8):e133
Here we report that the change from the red seeds of wild rice to the white seeds of cultivated rice (Oryza sativa) resulted from the strong selective sweep of a single mutation, a frame-shift deletion within the Rc gene that is found in 97.9% of white rice varieties today. A second mutation, also within Rc, is present in less than 3% of white accessions surveyed. Haplotype analysis revealed that the predominant mutation originated in the japonica subspecies and crossed both geographic and sterility barriers to move into the indica subspecies. A little less than one Mb of japonica DNA hitchhiked with the rc allele into most indica varieties, suggesting that other linked domestication alleles may have been transferred from japonica to indica along with white pericarp color. Our finding provides evidence of active cultural exchange among ancient farmers over the course of rice domestication coupled with very strong, positive selection for a single white allele in both subspecies of O. sativa. 相似文献
2.
S. Negrão M. M. Oliveira K. K. Jena D. Mackill 《Molecular breeding : new strategies in plant improvement》2008,22(2):159-168
The cultivated rice (Oryza sativa L.) has two subspecies, indica and japonica. The japonica rice germplasm has a narrower genetic diversity compared to the indica subspecies. Rice breeders aim to develop new varieties with a higher yield potential, with enhanced resistances to biotic
and abiotic stresses, and improved adaptation to environmental changes. In order to face some of these challenges, japonica rice germplasm will have to be diversified and new breeding strategies developed. Indica rice improvement could also profit from more “genepool mingling” for which japonica rice could play an important role. Interesting traits such as low-temperature tolerance, and wider climate adaptation could
be introgressed into the indica subspecies. In the past decade, huge developments in rice genomics have expanded our available knowledge on this crop and
it is now time to use these technologies for improving and accelerating rice breeding research. With the full sequence of
the rice genome, breeders may take advantage of new genes. Also new genes may be discovered from the genepool of wild relatives,
or landraces of the genus Oryza, and incorporated into elite japonica cultivars in a kind of “gene revolution” program. Expectedly, new technologies that are currently being optimized, aiming
for novel gene discovery or for tracking the regions under selection, will be suggested as new breeding approaches. This paper
revisits breeding strategies successfully employed in indica rice, and discusses their application in japonica rice improvement (e.g. ideotype breeding, wide hybridization and hybrid performance). 相似文献
3.
Tian Tang Suhua Shi 《植物学报(英文版)》2007,49(6):769-775
Domestication is a selection process that genetically modifies species to meet human needs. A most intriguing feature of domestication is the extreme phenotypic diversification among breeds. What could be the ultimate source of such genetic variations? Another notable outcome of artificial selection is the reduction in the fitness of domesticated species when they live in the wild without human assistance. The complete sequences of the two subspecies of rice cultivars provide an opportunity to address these questions. Between the two subspecies, we found much higher rates of non‐synonymous (N) than synonymous (S) substitutions and the N/S ratios are higher between cultivars than between wild species. Most interestingly, substitutions of highly dissimilar amino acids that are deleterious and uncommon between natural species are disproportionately common between the two subspecies of rice. We suggest strong selection in the absence of effective recombination may be the driving force, which we called the domestication‐associated Hill‐Robertson effect. These hitchhiking mutations may contribute to some fitness reduction in cultivars. Comparisons of the two genomes also reveal the existence of highly divergent regions in the genomes. Haplotypes in these regions often form highly polymorphic linkage blocks that are much older than speciation between wild species. Genes from such regions could contribute to the differences between indica and japonica and are likely to be involved in the diversifying selection under domestication. Their existence suggests that the amount of genetic variation within the single progenitor species Oryza rufipogon may be insufficient to account for the variation among rice cultivars, which may come from a more inclusive gene pool comprising most of the A‐genome wild species. Genes from the highly polymorphic regions also provide strong support for the independent domestication of the two subspecies. The genomic variation in rice has revealing implications for studying the genetic basis of indica‐japonica differentiation under rice domestication and subsequent improvement. 相似文献
4.
Molecular Evolution of the TAC1 Gene from Rice (Oryza sativa L.) 总被引:1,自引:0,他引:1
Jiahuan Jiang Lubin Tan Zuofeng Zhu Yongcai Fu Fengxia Liu Hongwei Cai Chuanqing Sun 《遗传学报》2012,39(10):551-560
Tiller angle is a key feature of the architecture of cultivated rice(Oryza sativa),since it determines planting density and influences rice yield.Our previous work identified Tiller Angle Control 1(TACl) as a major quantitative trait locus that controls rice tiller angle.To further clarify the evolutionary characterization of the TACl gene,we compared a TACl-containing 3164-bp genomic region among 113 cultivated varieties and 48 accessions of wild rice,including 43 accessions of O.rufipogon and five accessions of O.nivara.Only one single nucleotide polymorphism(SNP),a synonymous substitution,was detected in TACl coding regions of the cultivated rice varieties, whereas one synonymous and one nonsynonymous SNP were detected among the TACl coding regions of wild rice accessions.These data indicate that little natural mutation and modification in the TACl coding region occurred within the cultivated rice and its progenitor during evolution.Nucleotide diversities in the TACl gene regions of O.sativa and O.rufipogon of 0.00116 and 0.00112,respectively, further indicate that TACl has been highly conserved during the course of rice domestication.A functional nucleotide polymorphism (FNP) of TACl was only found in the japonica rice group.A neutrality test revealed strong selection,especially in the 3’-flanking region of the TACl coding region containing the FNP in the japonica rice group.However,no selection occurred in the indica and wild-rice groups.A phylogenetic tree derived from TACl sequence analysis suggests that the indica and japonica subspecies arose independently during the domestication of wild rice. 相似文献
5.
Asian cultivated rice(Oryza sativa L.),an important cereal crop worldwide,was domesticated from its wild ancestor 8000 years ago.During its long-term cultivation and evolution under diverse agroecological conditions, Asian cultivated rice has differentiated into indica and japonica subspecies.An effective method is required to identify rice germplasm for its indica and japonica features,which is essential in rice genetic improvements.We developed a protocol that combined DNA extraction from a single rice seed and the insertion/deletion(InDel) molecular fingerprint to determine the indica and japonica features of rice germplasm.We analyzed a set of rice germplasm,including 166 Asian rice varieties,two African rice varieties,30 accessions of wild rice species,and 42 weedy rice accessions,using the single-seeded InDel fingerprints(SSIF).The results show that the SSIF method can efficiently determine the indica and japonica features of the rice germplasm.Further analyses revealed significant indica and japonica differentiation in most Asian rice varieties and weedy rice accessions.In contrast,African rice varieties and nearly all the wild rice accessions did not exhibit such differentiation.The pattern of cultivated and wild rice samples illustrated by the SSIF supports our previous hypothesis that indica and japonica differentiation occurred after rice domestication under different agroecological conditions.In addition,the divergent pattern of rice cultivars and weedy rice accessions suggests the possibility of an endoferal origin(from crop)of the weedy rice included in the present study. 相似文献
6.
Yuanli Zhang Jiao Wang Xiaohui Zhang Jian-Qun Chen Dacheng Tian Sihai Yang 《Journal of molecular evolution》2009,68(4):393-402
Cultivated rice was domesticated from common wild rice. However, little is known about genetic adaptation under domestication.
We investigated the nucleotide variation of both cultivated rice and its wild progenitors at 22 R-gene and 10 non–R-gene loci. A significant regression was observed between wild rice and rice cultivars in their polymorphic levels, particularly
in their nonsynonymous substitutions (θ
a
). Our data also showed that a similar proportion (approximately 60%) of nucleotide variation in wild rice was retained in
cultivated rice in both R-genes and non–R-genes. Interestingly, the slope always was >1 and the intercept always >0 in linear regressions when a cultivar’s polymorphism
was x-axis. The slope and intercept values can provide a basis by which to estimate the founder effect and the strength of
artificial direct selection. A larger founder effect than previously reported and a strong direct-selection effect were shown
in rice genes. In addition, two-directional selection was commonly found in differentiated genes between indica and japonica rice subspecies. This kind of selection may explain the mosaic origins of indica and japonica rice subspecies. Furthermore, in most R-genes, no significant differentiation between cultivated and wild rice was detected. We found evidence for genetic introgression
from wild rice, which may have played an important role during the domestication of rice R-genes.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Yuanli Zhang and Jiao Wang contributed equally to this work. 相似文献
7.
H. S. Suh Y. I. Sato H. Morishima 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,94(3-4):316-321
Weedy rice (Oryza sativa L.) is an important resource for breeding and for studying the evolution of rice. The present study was carried out to identify
the genetic basis of the weedy rices distributed in various countries of the world. One hundred and fifty two strains of weedy
rice collected from Bangladesh, Brazil, Bhutan, China, India, Japan, Korea, Nepal, Thailand and the USA were tested for variations
in six morpho-physiological characteristics and in 14 isozyme loci. Twenty six weedy strains selected from the above materials
were assayed for the Est-10 locus, six RAPD loci of the nuclear genome, and one chloroplast locus. From the results of multivariate analysis based on
the morpho-physiological characteristics and the isozymes, weedy rice strains were classified into indica and japonica types, and each type was further divided into forms resembling cultivated and wild rice. Thus, four groups designated as
I, II, III and IV were identified. Weedy strains of group I (indica-type similar to cultivars) were distributed mostly in temperate countries, group II (indica-type similar to wild rice) in tropical countries, group III (japonica-type similar to cultivars) in Bhutan and Korea, group IV ( japonica-type similar to wild rice) in China and Korea. In group I, classified as indica, several strains showed japonica-specific RAPD markers, while some others had japonica cytoplasm with indica-specific RAPD markers in a heterozygous state at several loci. One weedy strain belonging to group II showed a wild rice-specific
allele at the Est-10 locus. However, in groups III and IV, no variation was ound either for the markers on Est-10 or for the RAPD loci tested. Judging from this study, weedy rice of group I might have originated at least partly from gene
flow between indica and japonica, whereas that of group II most probably originated from gene flow between wild and cultivated indica rice. Weedy rice of group III is thought to have originated from old rice cultivars which had reverted to a weedy form, and
that of group IV from gene flow between japonica cultivars and wild rice having japonica backgrounds.
Received: 2 May 1996 / Accepted: 30 August 1996 相似文献
8.
9.
H. Saruyama N. Shinbashi 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1992,84(7-8):947-951
Summary Proteins extracted from seed embryos of 29 different cultivated rice (Oryza sativa L.) and one wild rice (O. rufipogon Griff.) were compared by two-dimensional gel electrophoresis analysis. Among more than 300 protein spots on the gel we found some interesting variations in ten spots which were individually designated as proteins A-J. Protein E was observed in all indica cultivars but was not found in those of the subspecies japonica. In contrast, protein F was only detected in japonica cultivars. Protein A existed in all japonica cultivars but, with the exception of IR-36, could not be found in other indica cultivars. Therefore, proteins A, E and F can be used as markers for the identification of indica and japonica. Some so-called Javanica cultivars showed the characteristics of japonica subspecies with regard to proteins A and F, while one other cultivar of Javanica expressed a type intermediate between indica and japonica interms of proteins A and E. One feature discriminating between Javanica and japonica cultivars was found in the D, G, and J proteins which were expressed strongly in Javanica cultivars but were scarcely expressed in those of japonica. Expression of subspecies-specific proteins E and F in f1 hybrids was also investigated. 相似文献
10.
Despite extensive studies on cultivated rice, the genetic structure and subdivision of
this crop remain unclear at both global and local scales. Using 84 nuclear simple sequence
repeat markers, we genotyped a panel of 153 global rice cultivars covering all previously
recognized groups and 826 cultivars representing the diversity of Chinese rice germplasm.
On the basis of model-based grouping, neighbour-joining tree and principal coordinate
analysis, we confirmed the widely accepted five major groups of rice cultivars
(indica, aus, aromatic, temperate japonica and
tropical japonica), and demonstrated that rayada rice was unique in
genealogy and should be treated as a new (the sixth) major group of rice germplasm. With
reference to the global classification of rice cultivars, we identified three major groups
(indica, temperate japonica and tropical japonica) in Chinese
rice germplasm and showed that Chinese temperate japonica contained higher
diversity than that of global samples, whereas Chinese indica and tropical
japonica maintained slightly lower diversity than that present in the global
samples. Particularly, we observed that all seasonal, drought-tolerant and endosperm types
occurred within each of three major groups of Chinese cultivars, which does not support
previous claims that seasonal differentiation exists in Indica and
drought-tolerant differentiation is present in Japonica. It is most likely that
differentiation of cultivar types arose multiple times stemming from artificial selection
for adaptation to local environments. 相似文献
11.
Young-Jun Mo Ki-Young Kim Woon-Chul Shin Gun-Mi Lee Jong-Cheol Ko Jeong-Kwon Nam Bo-Kyeong Kim Jae-Kwon Ko Yeisoo Yu Tae-Jin Yang 《Genes & genomics.》2012,34(2):189-198
Sequence comparisons of ammonium transporter 1?C2 genes (OsAMT1-2) in different rice accessions revealed a MITE insertion in the upstream region of the gene. The 391-bp MITE, classified as a Mutator superfamily member and named Imcrop, included terminal inverted repeat (TIR) and 9-bp target site duplication (TSD) sequences. We identified 151 Imcrop elements dispersed on 12 chromosomes of the japonica reference genome. Of these, 12.6% were found in genic regions and 33.1% were located within 1.5 kb of annotated rice genes. We constructed comparative insertion maps with 111 and 102 intact Imcrop elements in the japonica and indica reference genomes, respectively. The Imcrop elements showed relatively even distribution across all chromosomes although their frequency was higher on chromosomes 1, 3, and 4 in both genomes. Seventy seven Imcrop elements were detected in both subspecies, whereas 34 and 25 insertions were found only in the japonica or indica genome, respectively. We compared insertion polymorphisms of 19 Imcrop elements found inside genes in 48 Korean rice cultivars, consisting of 42 japonica and six Tongil-types (indica-japonica cross). Thirteen insertions were common to all cultivars indicating these elements were present before indica-japonica divergence. The six other elements showed insertion polymorphisms among accessions, showing their recent insertion history or no critical positive effect of their insertion on the rice genome. 相似文献
12.
Yojiro Taniguchi Motoshige Kawata Ikuo Ando Tsutomu Shimizu Masahiro Ohshima 《Plant cell reports》2010,29(11):1287-1295
Bispyribac sodium (BS), a pyrimidinyl carboxy herbicide, is a well-known inhibitor of acetolactate synthase (ALS) activity.
ALS is an enzyme in the biosynthetic pathway for branched-chain amino acids. A mutant form of rice ALS (OsmALS [W548L/S627I]) that confers resistance to BS can be used as an in vitro selection marker gene for plant transformation. Since indica and indica-derived cultivars are thought to have lower BS sensitivity than japonica rice, the application of BS as a selectable reagent for genetic transformation in indica and indica-derived cultivars is more challenging than for japonica cultivars. In this study, callus and seedlings of eight different rice cultivars (five indica-derived cultivars, two indica cultivars and one japonica cultivar) were tested for BS sensitivity. Our study indicates for the first time that callus shows a higher sensitivity to
BS than seedlings in indica and indica-derived cultivars. We used BS with OsmALS [W548L/S627I] to select transformed calli, and transgenic rice plants from indica and indica-derived cultivars were successfully obtained. 相似文献
13.
Mohammed Nuruzzaman Tatsuo Kanno Rika Amada Yoshiki Habu Ichiro Kasajima Toshiki Ishikawa Maki Kawai-Yamada Hirofumi Uchimiya 《PloS one》2014,9(9)
The genomic nucleotide sequences of japonica rice (Sasanishiki and Nipponbare) contained about 2.7-kb unique region at the point of 0.4-kb upstream of the OsPsbS1 gene. In this study, we found that japonica rice with a few exceptions possessing such DNA sequences [denoted to OsMULE-japonica specific sequence (JSS)] is distinct by the presence of Mutator-like-element (MULE). Such sequence was absent in most of indica cultivars and Oryza glaberrima. In OsMULE-JSS1, we noted the presence of possible target site duplication (TSD; CTTTTCCAG) and about 80-bp terminal inverted repeat (TIR) near TSD. We also found the enhancement ofOsPsbS1 mRNA accumulation by intensified light, which was not associated with the DNA methylation status in OsMULE/JSS. In addition, O. rufipogon, possible ancestor of modern rice cultivars was found to compose PsbS gene of either japonica (minor) or indica (major) type. Transient gene expression assay showed that the japonica type promoter elevated a reporter gene activity than indica type. 相似文献
14.
Yinghua Pan Hongliang Zhang Dongling Zhang Jinjie Li Haiyan Xiong Jianping Yu Jilong Li Muhammad Abdul Rehman Rashid Gangling Li Xiaoding Ma Guilan Cao Longzhi Han Zichao Li 《PloS one》2015,10(3)
Low temperature affects the rice plants at all stages of growth. It can cause severe seedling injury and male sterility resulting in severe yield losses. Using a mini core collection of 174 Chinese rice accessions and 273 SSR markers we investigated cold tolerance at the germination and booting stages, as well as the underlying genetic bases, by association mapping. Two distinct populations, corresponding to subspecies indica and japonica showed evident differences in cold tolerance and its genetic basis. Both subspecies were sensitive to cold stress at both growth stages. However, japonica was more tolerant than indica at all stages as measured by seedling survival and seed setting. There was a low correlation in cold tolerance between the germination and booting stages. Fifty one quantitative trait loci (QTLs) for cold tolerance were dispersed across all 12 chromosomes; 22 detected at the germination stage and 33 at the booting stage. Eight QTLs were identified by at least two of four measures. About 46% of the QTLs represented new loci. The only QTL shared between indica and japonica for the same measure was qLTSSvR6-2 for SSvR. This implied a complicated mechanism of old tolerance between the two subspecies. According to the relative genotypic effect (RGE) of each genotype for each QTL, we detected 18 positive genotypes and 21 negative genotypes in indica, and 19 positive genotypes and 24 negative genotypes in japonica. In general, the negative effects were much stronger than the positive effects in both subspecies. Markers for QTL with positive effects in one subspecies were shown to be effective for selection of cold tolerance in that subspecies, but not in the other subspecies. QTL with strong negative effects on cold tolerance should be avoided during MAS breeding so as to not cancel the effect of favorable QTL at other loci. 相似文献
15.
Analysis of indica- and japonica-specific markers of Oryza sativa and their applications 总被引:1,自引:0,他引:1
Xiao-Jun Dai Yuan-Zhu Yang Liang Zhou Li-Jun Ou Man-Zhong Liang Wen-Jia Li Gong-Ping Kang Liang-Bi Chen 《Plant Systematics and Evolution》2012,298(2):287-296
Asian rice, Oryza sativa L., is one of the most important crop species. Genetic analysis has established that rice consists of several genetically
differentiated variety groups, with two main groups, namely, O. sativa ssp. japonica kata and ssp. indica
kata. To determine the genetic diversity of indica and japonica rice, 45 rice varieties, including domesticated rice and Asia common wild rice (O. rufipogon Griff.), were analyzed using sequence-related amplified polymorphism, target region amplified polymorphism, simple sequence
repeat, and intersimple sequence repeat marker systems. A total of 90 indica- and japonica-specific bands between typical indica and japonica subspecies were identified, which greatly helped in determining whether domesticated rice is of the indica or japonica type, and in analyzing the consanguinity of hybrid rice with japonica, which were bred from indica and japonica crossed offspring. These specific bands were both located in the coding and non-encoding region, and usually connected with
quantitative trait loci. Utilizing the indica-japonica-specific markers, japonica consanguinity was detected in sterile hybrid rice lines. Many indica-japonica-specific bands were found in O. rufipogon. This result supports the multiple-origin model for domesticated rice. Javanica exhibited a greater number of indica-japonica-specific bands, which indicates that it is a subspecies of O. sativa L. 相似文献
16.
Joong Hyoun Chin Sang-Ho Chu Wenzhu Jiang Young-Il Cho Reflinur Basyirin Darshan S. Brar Hee-Jong Koh 《Genes & genomics.》2011,33(1):39-48
Two subspecies in rice, japonica and indica, have their own ecotypic traits. However, reproductive barriers such as spikelet sterility in hybrid progenies between subspecies have been an obstacle in breeding programs for combining desirable traits from both subspecies through inter-subspecific hybridization. The 166 F9 RILs and two BC1F1s’ were analyzed for spikelet and pollen fertility with the parents and F1 between Dasanbyeo (DS, indica) / TR22183 (TR, japonica). A frame map was constructed using a total of 218 polymorphic STS and SSR markers. In both BC1F1s’ of DS//DS/TR and TR//DS/TR, clusters of significant QTLs for spikelet and pollen fertility were identified on the short arm of chromosome 5 and chromosome 8. Nine and ten digenic epistatic interactions for DS//DS/TR and TR//DS//TR were identified, respectively. HF-QTLs were detected at the similar position with subspecies-specific markers and segregation distortion loci, implying that HF-QTLs might be associated with the differentiation of indica and japonica. Hybrid fertility/sterility and its relationship with other traits are discussed in relation to the reproductive barriers between subspecies of rice. 相似文献
17.
C. N. Neeraja S. Malathi E. A. Siddiq 《Journal of plant biochemistry and biotechnology.》2006,15(1):39-41
Subspecific classification of Asian rice (Oryza sativa L) into indica and japonica has always been a subject of interest althrough for rice breeders and geneticists. The present study aims at identifying subspecies specific microsatellite markers in six genotypes, each of indica and japonica using 372 microsatellite primers covering the entire genome. Only 36 primers gave clear polymorphism on 3% agarose gel and these can be used as diagnostic markers for routine and easy identification of the subspecies. 相似文献
18.
Fengxia Liu Wenying Xu Qiang Wei Zhenghai Zhang Zhuo Xing Lubin Tan Chao Di Dongxia Yao Chunchao Wang Yuanjun Tan Hong Yan Yi Ling Chuanqing Sun Yongbiao Xue Zhen Su 《PloS one》2010,5(1)
Rice is a very important food staple that feeds more than half the world''s population. Two major Asian cultivated rice (Oryza sativa L.) subspecies, japonica and indica, show significant phenotypic variation in their stress responses. However, the molecular mechanisms underlying this phenotypic variation are still largely unknown. A common link among different stresses is that they produce an oxidative burst and result in an increase of reactive oxygen species (ROS). In this study, methyl viologen (MV) as a ROS agent was applied to investigate the rice oxidative stress response. We observed that 93-11 (indica) seedlings exhibited leaf senescence with severe lesions under MV treatment compared to Nipponbare (japonica). Whole-genome microarray experiments were conducted, and 1,062 probe sets were identified with gene expression level polymorphisms between the two rice cultivars in addition to differential expression under MV treatment, which were assigned as Core Intersectional Probesets (CIPs). These CIPs were analyzed by gene ontology (GO) and highlighted with enrichment GO terms related to toxin and oxidative stress responses as well as other responses. These GO term-enriched genes of the CIPs include glutathine S-transferases (GSTs), P450, plant defense genes, and secondary metabolism related genes such as chalcone synthase (CHS). Further insertion/deletion (InDel) and regulatory element analyses for these identified CIPs suggested that there may be some eQTL hotspots related to oxidative stress in the rice genome, such as GST genes encoded on chromosome 10. In addition, we identified a group of marker genes individuating the japonica and indica subspecies. In summary, we developed a new strategy combining biological experiments and data mining to study the possible molecular mechanism of phenotypic variation during oxidative stress between Nipponbare and 93-11. This study will aid in the analysis of the molecular basis of quantitative traits. 相似文献
19.
The resistance (R) genes and defense response (DR) genes have become very important resources for the development of disease resistant cultivars. In the present investigation, genome-wide identification, expression, phylogenetic and synteny analysis was done for R and DR-genes across three species of rice viz: Oryza sativa ssp indica cv 93-11, Oryza sativa ssp japonica and wild rice species, Oryza brachyantha. We used the in silico approach to identify and map 786 R -genes and 167 DR-genes, 672 R-genes and 142 DR-genes, 251 R-genes and 86 DR-genes in the japonica, indica and O. brachyanth a genomes, respectively. Our analysis showed that 60.5% and 55.6% of the R-genes are tandemly repeated within clusters and distributed over all the rice chromosomes in indica and japonica genomes, respectively. The phylogenetic analysis along with motif distribution shows high degree of conservation of R- and DR-genes in clusters. In silico expression analysis of R-genes and DR-genes showed more than 85% were expressed genes showing corresponding EST matches in the databases. This study gave special emphasis on mechanisms of gene evolution and duplication for R and DR genes across species. Analysis of paralogs across rice species indicated 17% and 4.38% R-genes, 29% and 11.63% DR-genes duplication in indica and Oryza brachyantha, as compared to 20% and 26% duplication of R-genes and DR-genes in japonica respectively. We found that during the course of duplication only 9.5% of R- and DR-genes changed their function and rest of the genes have maintained their identity. Syntenic relationship across three genomes inferred that more orthology is shared between indica and japonica genomes as compared to brachyantha genome. Genome wide identification of R-genes and DR-genes in the rice genome will help in allele mining and functional validation of these genes, and to understand molecular mechanism of disease resistance and their evolution in rice and related species. 相似文献