Oryza minuta

Ninety-three accessions representing 21 species from the genus Oryza were examined for restriction fragment length polymorphism. The majority (78%) of the accessions, for which five individuals were tested, were found to be monomorphic. Most of the polymorphic accessions segregated for only one or two probes and appeared to be mixed pure lines. For most of the Oryza species tested, the majority of the genetic variation (83%) was found between accessions from different species with only 17% between accessions within species...

Enzyme electrophoresis was used to compare the isozyme phenotypes of Oryza sativa, IR31917 (AA genome), and two O. minuta accessions (Om 101089 and Om101141; BBCC genome) for ten enzyme systems. Between the two species, two systems were monomorphic (isocitrate dehydrogenase and alcohol dehydrogenase) and eight were polymorphic (shikimate dehydrogenase, phosphogluconate dehydrogenase, phosphoglucose isomerase, malate dehydrogenase, glutamate oxaloacetate transaminase, esterase, aminopeptidase, and endopeptidase)...

Crosses were made between four varieties ('Mahsuri', 'Setanjung", 'MR84" and 'MR103") of Oryza sativa L. (2n=24, AA) and one accession of O. minuta (2n= 8, BBCC). The seed set obtained ranged between 9.5% and 25.1% depending on the rice variety used. By rescuing 14-day-old embryos and culturing them on 25%-strength MS medium we obtained a total of 414 F1 hybrids. The F1s were vigorous, tillered profusely, were perennial and male-sterile. The hybrids were triploid (ABC) with 36 chromosomes and showed irregular meiosis...

The rice disease resistance (R) gene Xa3/Xa26 (having also been named Xa3 and Xa26) against Xanthomonas oryzae pv. oryzae (Xoo), which causes bacterial blight disease, belongs to a multiple gene family clustered in chromosome 11 and is from an AA genome rice cultivar (Oryza sativa L.). This family encodes leucine-rich repeat (LRR) receptor kinase-type proteins. Here, we show that the orthologs (alleles) of Xa3/Xa26, Xa3/Xa26-2, and Xa3/Xa26-3, from wild Oryza species O. officinalis (CC genome) and O. minuta (BBCC genome), respectively, were also R genes against Xoo...

Rice blast, caused by the fungal pathogen Magnaporthe oryzae, is a devastating disease of rice worldwide. Among the 85 mapped resistance (R) genes against blast, 13 have been cloned and characterized. However, how these genes originated and how they evolved in the Oryza genus remains unclear. We previously cloned the rice blast R-genes Pi2, Pi9, and Piz-t, and analyzed their genomic structure and evolution in cultivated rice. In this study, we determined the genomic sequences of the Pi2/9 locus in four wild Oryza species representing three genomes (AA, BB and CC)...

Screening of the expressed sequence tag library of the wild rice species Oryza minuta revealed an unknown gene that was rapidly and strongly induced in response to attack by a rice fungal pathogen (Magnaporthe oryzae) and an insect (Nilaparvata lugens) and by wounding, abscisic acid (ABA), and methyl jasmonate treatments. Its recombinant protein was identified as a bifunctional nuclease with both RNase and DNase activities in vitro. This gene was designated OmBBD (for O. minuta bifunctional nuclease in basal defense response)...

Oryza minuta, a tetraploid wild relative of cultivated rice, is an important source for the genetic improvement. Interspecific hybrids were obtained from the cross of O. sativa L. (IR24) and O. minuta (Acc. No. 101133) with 5.58% crossability, which ranged from 0.11% to 1.62% in the backcross generations. The chromosome numbers of the backcross progenies were 24 to 48. Seven yield-related traits of the parents, hybrid F(1), and backcross progenies were evaluated. Simple sequence repeat markers analysis showed that the polymorphism ratio of SSR bands between IR24 and Acc...

BACKGROUND: The role of gene duplication in the structural and functional evolution of genomes has been well documented. Analysis of complete rice (Oryza sativa) genome sequences suggested an ancient whole genome duplication, common to all the grasses, some 50-70 million years ago and a more conserved segmental duplication between the distal regions of the short arms of chromosomes 11 and 12, whose evolutionary history is controversial. RESULTS: We have carried out a comparative analysis of this duplication within the wild species of the genus Oryza, using a phylogenetic approach to specify its origin and evolutionary dynamics...

Brown planthopper (BPH) is one of the most destructive insect pests of rice. Wild species of rice are a valuable source of resistance genes for developing resistant cultivars. A molecular marker-based genetic analysis of BPH resistance was conducted using an F(2) population derived from a cross between an introgression line, 'IR71033-121-15', from Oryza minuta (Accession number 101141) and a susceptible Korean japonica variety, 'Junambyeo'. Resistance to BPH (biotype 1) was evaluated using 190 F(3) families...

Comparative genomics is a powerful tool to decipher gene and genome evolution. Placing multiple genome comparisons in a phylogenetic context improves the sensitivity of evolutionary inferences. In the genus Oryza, this comparative approach can be used to investigate gene function, genome evolution, domestication, polyploidy, and ecological adaptation. A large genomic region surrounding the MONOCULM1 (MOC1) locus was chosen for study in 14 Oryza species, including 10 diploids and 4 allotetraploids. Sequencing and annotation of 18 bacterial artificial chromosome clones for these species revealed highly conserved gene colinearity and structure in the MOC1 region...

Wild progenitor species provide potential gene sources for complex traits such as yield and multiple resistances to biotic and abiotic stresses, and thus are expected to contribute to sustainable food supplies. An introgression line 'IR71033-121-15' was derived from a wild species Oryza minuta (2n = 48, BBCC, Acc No. 101141) at IRRI. Introgression analysis using 530 SSR and STS markers revealed that at least 14 chromosomal segments distributed over 12 chromosomes had been introgressed from O. minuta. An F2:3 population from the cross between IR71033 and Junambyeo (a Korean japonica cultivar) consisting of 146 lines was used for quantitative trait loci (QTL) analysis of 16 agronomic traits...

The mitogen-activated protein kinase (MAPK) signaling cascade is critical for regulating plant defense systems against various kinds of pathogen and environmental stresses. One component of this cascade, the MAP kinase kinases (MAPKK), has not yet been shown to be induced in plants following biotic attacks, such as those by insects and fungi. We describe here a gene coding for a blast (Magnaporthe grisea)- and insect (Nilaparvata lugens)-responsive putative MAPK kinase, OmMKK1 (Oryza minuta MAPKK 1), which was identified in a library of O...

Simple sequence repeats (SSR) and their flanking regions in the mitochondrial and chloroplast genomes were sequenced in order to reveal DNA sequence variation. This information was used to gain new insights into phylogenetic relationships among species in the genus Oryza. Seven mitochondrial and five chloroplast SSR loci equal to or longer than ten mononucleotide repeats were chosen from known rice mitochondrial and chloroplast genome sequences. A total of 50 accessions of Oryza that represented six different diploid genomes and three different allopolyploid genomes of Oryza species were analyzed...

A subtracted library was constructed from planthopper-infested wild rice (Oryza minuta) by suppression subtractive hybridization in combination with mirror orientation selection. To screen the differentially expressed transcripts in the library, we applied a cDNA microarray containing 960 random clones in a reverse Northern blot analysis using cDNA probes prepared from the mRNAs of control and planthopper-infested samples. On the basis of the signal intensities and expression ratios obtained from experiments performed in triplicate, we selected 383 clones...

A subtracted library was constructed from wound-treated wild rice (Oryza minuta) by suppression subtractive hybridization (SSH) in combination with mirror orientation selection (MOS). To distinguish between differentially expressed transcripts and false positive clones, DNA chips containing 960 random clones were applied as a form of reverse Northern screening. Based on the signal intensities and expression ratios obtained from experiments performed in triplicate, 371 clones were selected. ESTs produced from the subtracted library showed 63...

Bacterial blight of rice, caused by Xanthomonas oryzae pv. oryzae ( Xoo) (Ishyama) Dye, is one of the serious diseases prevalent throughout Asia. In a previous study, a resistance ( R) locus was transferred from the tetraploid wild rice Oryza minuta to the cultivated rice species, Oryza sativa L. Here, we report the fine genetic mapping of the R locus, tentatively designated as Xa27(t). We performed disease evaluation with an Xa27(t) near-isogenic line, IRBB27, testing 35 Xoo strains collected from 11 countries...

The expressed sequence tags (ESTs) presented in this report are the first transcriptomes of wild rice. A cDNA library was constructed from 4-week-old leaf samples of greenhouse-grown Oryza minuta. The 5,211 cDNA clones of O. minuta represent 3,401 unique sequences, consisting of 2,787 singletons and 614 assembled sequences. Database comparisons of the cDNAs in GenBank's non-redundant databases using BLAST revealed that 4,957 of the 5,211 cDNAs (95.1%) showed a high degree of sequence homology to genes from other organisms...

The results presented here support the hypothesis that plants of the tribe Oryzeae respond enantioselectively and homogeneously to optically active 1-alpha-methylbenzyl-3-p-tolylurea (MBTU) in root growth inhibition, in contrast to Echinochloa species. The Oryzeae plants tested in this study belong to different genera (Oryza, Leersia, Chikusichloa and Zizania), to different species (O sativa, O glaberrima, O alta, O coarctata, O latifolia, O minuta, O rufipogon), to various ecospecies of Oryza (japonica, indica, japonica x indica, javanica) and to different levels of evolution [cultivated rice (O sativa and O glaberrima) and ancestral wild rice species]...

To identify fungal stress-related genes in wild rice, Oryza minuta, we constructed a subtracted library using suppression subtractive hybridization in combination with mirror orientation selection. DNA chips containing 960 randomly selected cDNA clones were applied by reverse Northern analysis to eliminate false positive clones from the library and to prescreen differentially expressed genes. In total, 377 cDNA clones were selected on the basis of their signal intensities and expression ratios. Sequence analyses of these 377 cDNA fragments revealed that 180 of them (47...

Several diazotrophic species of Azoarcus spp. occur as endophytes in the pioneer plant Kallar grass. The purpose of this study was to screen Asian wild rice and cultivated Oryza sativa varieties for natural association with these endophytes. Populations of culturable diazotrophs in surface-sterilized roots were characterized by 16S rDNA sequence analysis, and Azoarcus species were identified by genomic fingerprints. A. indigens and Azoarcus sp. group C were detected only rarely, whereas Azoarcus sp. group D occurred frequently in samples of flooded plants: in 75% of wild rice, 80% of land races of O...