A Recessive Mutation in Rice Conferring Non-Race-Specific Resistance to Bacterial Blight and Blast

To understand the basis of broad-spectrum disease resistance in rice, we isolated a gamma-ray-induced IR64 mutant G978 that showed enhanced resistance to blast and bacterial blight. The resistance is quantitative and non-race specific against the bacterial and fungal pathogens. The mutation is inherited as a single recessive gene, designated as Bsdr1 and causes shorter stature relative to the wild type; however, it does not show lesion mimics phenotype under the conditions tested. The mutation was mapped as a quantitative trait locus to a 3.8-Mb region on chromosome 12. By comparing the gene expression profiles of the mutant and wild type, we identified a candidate gene encoding a U-box domain-containing protein. The disrupted gene showed a loss of expression in the mutant and co-segregated with mutant phenotype. The mutant provides a useful tool for investigating the important genes responsible for non-race specific resistance to two distinct diseases.     

Identification of quantitative trait loci for downy mildew resistance in cucumber (Cucumis sativus L.)

Downy mildew, caused by Pseudoperonospora cubensis (Berk. & Curt.) Rostov, is one of the most economically important foliar diseases in cucumber (Cucumis sativus L.). Cucumber line CS-PMR1, derived from self-pollination of USDA Plant Introduction 197088, has a high level of resistance to downy mildew and is considered to be promising breeding material. In this study, we performed quantitative trait locus (QTL) analysis for downy mildew resistance using 111 recombinant inbred lines (RILs) derived from a cross between CS-PMR1 and the old Japanese cultivar Santou, which exhibits moderate resistance. The resistance of the RILs and their parents was evaluated by diverse methods using different plant organs (cotyledons, true leaves), stages (seedlings and adult plants), and evaluation criteria (lesion expansion and extent of sporulation). The high resistance of CS-PMR1 was associated with many QTLs with relatively small effects, whereas the moderate resistance of Santou was associated with one major QTL and possibly two others with relatively small effects. In all assays, the major QTL at which the Santou allele was associated with increased resistance had the largest effect. This QTL allele from Santou and several of the most effective QTL alleles identified in CS-PMR1 should be highest priority for selection to efficiently breed new cultivars that carry adequate levels of downy mildew resistance.     

Identification of avirulence genes in the rice blast fungus corresponding to three resistance genes in Japanese differentials

The pathogenicity of progeny from crosses among three Chinese isolates of Magnaporthe grisea collected from rice was tested on three Japanese differentials (Ishikarishiroke, Aichiasahi, K 59) having the blast resistance genes Pii, Pia, and Pit, respectively. Monogenic control was demonstrated for avirulence to the differentials. To identify resistance genes corresponding to the avirulence genes, the resistance and susceptibility in F₃ lines of the cultivars in response to the parents of the crosses were analyzed genetically. The three avirulence genes identified, designated Avr-Pii, Avr-Pia, and Avr-Pit, appear to correspond to resistance genes Pii, Pia, and Pit, respectively. The monogenic control of avirulence in the fungus and monogenic dominant resistance in rice cultivars supports a gene-for-gene relation in the Pii-, Pia-, or Pit-dependent resistance to the rice blast fungus in rice cultivars.     

Allelic loss analysis of lymphomas induced in Fas-heterozygous deficient mice

Mutations of Fas (CD95/Apo-1) gene have been reported in various malignancies and therefore the Fas gene has been considered to be a tumor suppressor gene. To examine an involvement of Fas gene as a tumor suppressor gene in radiation lymphomagenesis, we examined the loss of heterozygosity (LOH) in lymphomas from (MSM/Ms x MRL-MpJ/Fas (lpr)) F(1) and (BALB/cHeA x MRL-MpJ/Fas (lpr)) F(1) hybrid mice. Lymphoma development by X-irradiation was efficiently observed in both F(1) hybrids. Frequent LOH was found on chromosomes 12 and 4 in the tumors from both F(1) mice, but no allelic loss on chromosome 19 containing Fas locus was found, and no wild-type allele of the Fas gene was lost in 51 lymphomas. Therefore, the putative tumor-suppressor gene regions responsible for lymphomagenesis might not considerably differ due to the Fas gene status.     

Numerical Simulation of the Springtime Trans-Boundary Air Pollution in East Asia

Water, Air, &; Soil Pollution - During the spring, the high concentrations of ozone (O3) and aerosols are frequently observed aloft in Japan. Such episodes supposedly are caused by the...     

Atmospheric Deposition of Acidifying Components to a Japanese Cedar Forest

One-year field measurements were conducted in a Japanese cedar (Cryptomeria japonica) forest, located in Gunma Prefecture, Japan. On the basis of the meteorological and atmospheric concentration data, the dry deposition of SO₂, HNO₃, NO₂ and HCl was estimated using the inferential method. The annual dry deposition of H⁺ was estimated at 721 eq ha^?1yr^?1, which was 40% larger than the measured annual wet deposition of H⁺ (514 eq ha^?1yr^?1). Therefore, dry deposition is an important pathway for the atmospheric input of H⁺ to the forest in the study site. The contribution of each gas to the dry deposition of H⁺ was as follows: SO₂, 25%; HNO₃, 32%; NO₂, 10%; and HCl, 33%. The extremely high contribution of HCl appeared to be caused by the high emission intensity of HCl due to waste incineration in the site region. The differences between estimated deposition and throughfall and stemflow measurements indicated that about 80% of the total deposition of H⁺ was taken up by the canopy.     

Detection of SNPs in fish DNA: application of the fluorogenic ribonuclease protection (FRIP) assay for the authentication of food contents

The fluorogenic ribonuclease protection (FRIP) assay was used to detect single nucleotide polymorphisms (SNPs) in commercially produced fish products. By using fluorescence resonance energy transfer (FRET) between fluorophore and quencher labeled probes, the species-specific cleavage of sample RNA was detected by measuring the fluorescence intensity during the FRIP assay. We were able to discriminate raw and thermally processed eel and tuna species using the FRIP-based SNP detection method. Furthermore, the intensity of fluorescence was correlated with the mutant/wild-type ratio. These results suggest that the FRIP assay is a useful method for the in situ confirmation of labels of fishery foods during food production.