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Depiction of genetic divergence in rice (Oryza sativa L.)  [PDF]
Praveen Pandey,P. John Anurag
Advances in Agriculture & Botanics , 2010,
Abstract: The nature and magnitude of genetic divergence in 40 rice (Oryza sativa L.) genotypes fortwelve yield and yield component were assessed using Mahalanobis D2-statistics. The analysis ofvariance revealed highly significant differences for all the characters under studied, indicating thatthere is an ample scope for isolation of promising lines from present gene pool for yield improvement.On the basis of D2 values the genotypes were grouped into seven clusters. Cluster VI was the largestcontaining 11 genotypes followed by cluster III with 9 genotypes. The composition of clusters indicatednon existence of correspondence between genetic diversity and geographical distribution. Plant height,biological yield and test weight contributed considerably, accounting for 86.16 % of total divergence.The highest intercluster distance was observed between cluster II and VII therefore the genotypesfrom cluster II (Triguna, MAUB-15, Pant dhan-6) having desired mean values for characters like daysto 50% flowering, panicle length and harvest index, were more divergent from the genotypes of clusterVII (Sonachur & Mala) having desired mean values for plant height, flag leaf width, spikelets perpanicle, biological yield and test weight, may be used in hybridization programme to achieve desiredsegregants with higher yield
Differential Response of Two Scented Indica Rice (Oryza sativa) Cultivars under Salt Stress  [PDF]
Sunita Danai-Tambhale,Vinay Kumar,Varsha Shriram
Journal of Stress Physiology & Biochemistry , 2011,
Abstract: Present report deals with the effect of varying (0 – 200 mM NaCl) salt stress on two popular scented non-basmati type indica rice cultivars, namely Indrayani and Ambemohar on germination and growth and biochemical parameters. In the present investigation the effect of increasing salt stress was seen on germination, biomass production and biochemical parameters including total protein content, proline accumulation, starch content, polyphenols levels, and reducing and non-reducing sugars. Contrasting behavior was evidenced in both the cultivars in terms of germination rate and biomass production at seedling and early vegetative growth level. Salt stress-induced proline accumulation was observed in both the cultivars, however, with much higher extent of proline accumulation in Ambemohar than Indrayani. A salinity stress of 200 mM NaCl resulted into 305% higher proline content than the control plants of Ambemohar against 222% higher proline in Indrayani at the same stress level. Similarly protein content was also higher in Ambemohar than Indrayani at the highest stress level used in this study. Contrasting results were seen in terms of starch content amongst both the cultivars, where continuous decrease with increasing salt stress was observed in Indrayani, on the other hand, an increase in starch content was evident in Ambemohar under the influence of NaCl-induced salt stress. These finding clearly indicates the comparably higher salt tolerant nature of Ambemohar than Indrayani which might be attributed to higher proline, protein and starch content than Indrayani cultivar under salt stress.
Agrobotanical Characteristics of Some West African Indigenous Species of the a Genome Complex of the Genus Oryza Linn  [PDF]
Francisca Aladejana,Julius Olaoye Faluyi
International Journal of Botany , 2007,
Abstract: This study collected and characterized accessions of three indigenous and one cultivated species of the A genome complex of the genus Oryza Linn. with the objective of identifying the valuable botanical and agro-botanical characters in them. The germplasm collection confirmed that the four species of the A-genome complex: Oryza barthii A. Chev., Oryza glaberrima Steud, O. longistaminata A. Chev. and Roehr and O. sativa Linn. are abundant in the savanna agroecology of Nigeria. The restricted occurrence of O. glaberrima suggests that it has attained the status of a lost crop. The species studied have been delineated on the basis of morphometric parameters involving awns, grain length and shape, panicle branching, rhizomatous habit, ligule shape and form, presence or absence of secondary branches and perennial or annual habit. The results have been able to identify botanical attributes for species differentiation and useful agronomic attributes in the wild rice species as genetic resources both for the improvement of O. sativa and possibly some of the wild species per se. These attributes include: insensitivity to photoperiod, long grains, awnlessness, dense panicle, high yield parameters, high food value and tillering habit. Findings also revealed considerable variability in the gene pool of the species studied for the improvement of the rice crop.
Origin of Oryza sativa in China Inferred by Nucleotide Polymorphisms of Organelle DNA  [PDF]
Xin Wei, Rongsheng Wang, Lirong Cao, Nannan Yuan, Juan Huang, Weihua Qiao, Wanxia Zhang, Hanlai Zeng, Qingwen Yang
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0049546
Abstract: China is rich of germplasm resources of common wild rice (Oryza rufipogon Griff.) and Asian cultivated rice (O. sativa L.) which consists of two subspecies, indica and japonica. Previous studies have shown that China is one of the domestication centers of O. sativa. However, the geographic origin and the domestication times of O. sativa in China are still under debate. To settle these disputes, six chloroplast loci and four mitochondrial loci were selected to examine the relationships between 50 accessions of Asian cultivated rice and 119 accessions of common wild rice from China based on DNA sequence analysis in the present study. The results indicated that Southern China is the genetic diversity center of O. rufipogon and it might be the primary domestication region of O. sativa. Molecular dating suggested that the two subspecies had diverged 0.1 million years ago, much earlier than the beginning of rice domestication. Genetic differentiations and phylogeography analyses indicated that indica was domesticated from tropical O. rufipogon while japonica was domesticated from O. rufipogon which located in higher latitude. These results provided molecular evidences for the hypotheses of (i) Southern China is the origin center of O. sativa in China and (ii) the two subspecies of O. sativa were domesticated multiple times.
Genetic structure and diversity of Oryza sativa L. in Guizhou, China
DongLing Zhang,HongLiang Zhang,XingHua Wei,YongWen Qi,MeiXing Wang,JunLi Sun,Li Ding,ShengXiang Tang,Zong’En Qiu,YongSheng Cao,XiangKun Wang,ZiChao Li
Chinese Science Bulletin , 2007, DOI: 10.1007/s11434-007-0063-x
Abstract: Preserving many kinds of rice resources and rich variations, Guizhou Province is one of the districts with the highest genetic diversity of cultivated rice (Oryza sativa L.) in China. In the current research, genetic diversity and structure of 537 accessions of cultivated rice from Guizhou were studied using 36 microsatellite markers and 39 phenotypic characters. The results showed that the model-based genetic structure was the same as genetic-distance-based one using SSRs but somewhat different from the documented classification (mainly based on phenotype) of two subspecies. The accessions being classified into indica by phenotype but japonica by genetic structure were much more than that being classified into japonica by phenotype but indica by genetic structure. Like Ding Ying’s taxonomic system of cultivated rice, the subspecific differentiation was the most distinct differentiation within cultivated rice. But the differentiation within indica or japonica population was different: japonica presented clearer differentiation between soil-watery ecotypes than indica, and indica presented clearer differentiation between seasonal ecotypes than japonica. Cultivated rices in Guizhou revealed high genetic diversity at both DNA and phenotypic levels. Possessing the highest genetic diversity and all the necessary conditions as a center of genetic diversity, region Southwestern of Guizhou was suggested as the center of genetic diversity of O. sativa L. from Guizhou.
Genetic diversity of rice cultivars (Oryza sativa L.) in China and the temporal trends in recent fifty years
Genetic diversity of rice cultivars (Oryza sativa L.) in China and the temporal trends in recent fifty years

QI Yongwen,ZHANG Dongling,ZHANG Hongliang,WANG Meixing,SUN Junli,WEI Xinghua,QIU Zongen,TANG Shengxiang,CAO Yongsheng,WANG Xiangkun,LI Zichao,
QI
,Yonawen,ZHANG,Dongling,ZHANG,Hongliang,WANG,Meixing,SUN,Junli,WEI,Xinghua,QIU,Zongen,TANG,Shengxiang,CAO,Yongsheng,WANG,Xiangkun,LI,Zichao

科学通报(英文版) , 2006,
Abstract: To understand geographical distribution of the genetic diversity of rice cultivars {Oryza sativa L.) and its trends in recent fifty years in China, 453 ' accessions were analyzed by 36 microsatellites loci and 42 phenotypic traits. Results revealed that the genetic diversity by SSRs is highly consistent with that by phenotypic traits and the genetic diversity of indica cultivars was higher than that of japonica cultivars; the genetic diversity of cultivars declined from 1950s to 1980s and then increased greatly; among the six rice ecological zones (REZs), genetic diversity of REZTl was the highest and those of REZV and REZVT were the lowest at both DNA and phenotypic level. Jiangsu and Jiangxi provinces in the middle and lower reaches of Yangtze River and Sichuan province in southwest of China were the areas with the highest genetic diversity. Breeders in REZV which is an important japonica rice area but with very low genetic diversity should explore more gene resources to widen the genetic backgrounds of cultivars.
Expression of RNA polymerase IV and V in Oryza sativa
Moo,Leydi de Rocio Canche; González,Angela Kú; Rodríguez-Zapata,Luis Carlos; Suarez,Victor; Casta?o,Enrique;
Electronic Journal of Biotechnology , 2012,
Abstract: rna polymerase iv and v are principal players in the rddm pathway, where their current study has shown interaction of several factors that control dna silencing of intergenic regions and sirna production. dna silencing is an important process during cell differentiation, nuclear structure and viral control. however, rna pol iv and v are yet to be study in model monocot systems like oryza sativa that can provide further information on genetic silence mechanism in plats. we show the expression pattern of these polymerases in tissues extracts of oryza sativa. detectable amounts of these polymerases are found in specific adult plant tissues and particularly expressed during somatic embryogenesis but not during early stages of normal embryo development. the use of synthetic auxin leads to an induction of both rna pol iv and v in scutellum tissue where nuclear localization may be required for genome reorganization and gene silencing.
Assessment of genomic relationship between Oryza sativa and Oryza australinesis
FM Abbasi, H Ahmad, F Perveen, M Inamullah, M Sajid, DS Brar
African Journal of Biotechnology , 2010,
Abstract: The genomic relationship between Oryza sativa (2n = 24 AA) and Oryza australinesis (2n = 24 EE) has not been established. Genomic relationship between these two species was assessed by using three strategies: genomic in situ hybridization (GISH), meiotic chromosome pairing, pollen and spikelet sterility. The hybrid was produced between these two species at the International Rice Research Institute using embryo rescue technique. The chromosome pairing was examined in pollen mother cells of O. australinesis, O. sativa and the hybrid between O. sativa and O. australinesis. The hybrid was highly sterile with pollen stain ability being 0.05%. Both parents showed regular meiosis with normal chromosome pairing. The F1 hybrid exhibited limited chromosome pairing. On an average, 0 - 4 bivalents and 16 - 24 univalents were recorded at metaphase-1. The most frequent configuration was two bivalent and twenty univalent. The chromosomes of O. australiensis appeared larger and darkly stained. For genomic in situ hybridization, genomic DNA from O. australiensis was used as probe for the mitotic and meiotic chromosomes of the hybrid between O. sativa and O. australiensis. GISH revealed unequivocal discrimination of O. australiensis chromosomes that appeared yellow due to hybridization signal from O. sativa chromosomes that fluoresced red due to counterstaining with propidium iodide (PI). No cross hybridization was examined between the labeled genomic DNA of O. australiensis and the chromosomes of O. sativa. The paired chromosomes were discriminated as autosyndetic and allosyndetic pairing. Meiotic and mitotic chromosomes of the O. australiensis and O. sativa, in the hybrid were discriminated by GISH for the first time. Results showed that both genomes were highly divergent.
An Assessment of Wx Microsatellite Allele, Alkali Degradation and Differentiation of Chloroplast DNA in Traditional Black Rice (Oryza sativa L.) From Thailand and Lao PDR
Preecha Prathepha
Pakistan Journal of Biological Sciences , 2007,
Abstract: Thailand and Lao PDR are the country’s rich rice diversity. To contribute a significant knowledge for development new rice varieties, a collection of 142 black rice (Oryza sativa) accessions were determined for variation of physico-chemical properties, Wx microsatellite allele, Wx allele and chloroplast DNA type. The results showed that amylose content of black rice accessions were ranged from 1.9 to 6.8%. All of the alkali disintegration types (high, intermediate and low) was observed in these rice with average of 1.75 on the 1-3 digestibility scale. The unique Wx microsatellite allele (CT)17 was found in these samples and all black rice strains carried Wxb allele. In addition, all black rice accessions were found the duplication of the 23 bp sequence motif in the exon 2 of the wx gene. This evidence is a common phenomenon in glutinous rice. Based on two growing condition for black rice, rainfed lowland and rainfed upland, chloroplast DNA type was distinct from each other. All rice strains from rainfed lowland was deletion plastotype, but all other rainfed upland strains were non-deletion types.
Use of multivariate analysis in mineral accumulation of rocket (Eruca sativa) accessions  [PDF]
Bozokalfa Kadri M.,E?iyok Dursun,Ya?mur Bülent
Genetika , 2011, DOI: 10.2298/gensr1103437b
Abstract: The leafy vegetables contain high amount of mineral elements and health promoting compound. To solve nutritional problems in diet and reduced malnutrition among human population selection of specific cultivar among species would be help increasing elemental delivery in the human diet. While rocket plant observes several nutritional compounds no significant efforts have been made for genetic diversity for mineral composition of rocket plant accessions using multivariate analyses technique. The objective of this work was to evaluate variability for mineral accumulation of rocket accessions revealed by multivariate analysis to use further breeding program for achieve improving cultivar in targeting high nutrient concentration. A total twelve mineral element and twenty-three E. sativa accessions were investigated and considerable variation were observed in the most of concentration the principal component analysis explained that 77.67% of total variation accounted for four PC axis. Rocket accessions were classifies into three groups and present outcomes of experiments revealed that the first three principal components were highly valid to classify the examined accessions and separating mineral accumulations. Significant differences exhibited in mineral concentration among examined rocket accessions and the result could allow selecting those genotypes with higher elements.
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