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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 115 (1996), S. 0 
    ISSN: 1439-0523
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Low-temperature-sensitive sterility has become one of the major obstacles in indica–japonica hybrid rice breeding. The objectives of this paper were to evaluate the extent of the fertility reduction and to determine the genetic basis of low-temperature-sensitive sterility. Seventeen varieties were crossed in various ways to produce 21 F1s including 16 indica-japonica hybrids. Fertility of the F1s and their parents was examined under both high and low temperature conditions. Considerable reduction in spikelet fertility was observed under low-temperature conditions in the majority of the indica–japonica hybrids having at least one wide compatibility parent. However, the extent of fertility reduction varied greatly, depending on the parental genotypes. Data from five pairs of reciprocal crosses indicated that the cytoplasm had no effect on fertility reduction. The more-or-less bimodal distribution of the fertility segregation of one BC1F1 and two F2: populations under low-temperature conditions suggested that the low-temperature-sensitive sterility was controlled by only one or a few genes. It was also shown that the low-temperature-sensitivity is not related to wide compatibility. We conclude that it is possible to develop indica-japonica hybrids with wide compatibility and also insensitivity to the low-temperature conditions.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1572-9028
    Schlagwort(e): CO hydrogenation ; EXAFS characterization ; FTIR characterization ; Ru, RuCo and Co carbonyl clusters in NaY and NaX zeolites
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Some Ru and Co carbonyl clusters in zeolite pores such as Ru3(CO)12/NaY, [HRu6(CO)18]−/NaY, [Ru6(CO)18]2−/NaX, Co4(CO)12/NaY and Co6(CO)16/NaY were prepared by the ship-in-bottle technique, and characterized by FTIR and EXAFS. The RuCo bimetallic carbonyl cluster was prepared by reductive carbonylation of the oxidized RuCo/NaY, which provides the proposed assignment to [HRUCo3(CO)12]/NaY. The tailored Ru, RuCo and Co catalysts were prepared by H2 reduction from the precursors, e.g. Ru, RuCo bimetallic and Co carbonyl clusters impregnated on SiO2 and entrapped in NaY and NaX zeolites. The RuCo bimetallic carbonyl cluster-derived catalysts showed substantially higher activities and selectivities for oxygenates such as C1–C5 alcohols in CO hydrogenation (CO/H2 = 0.33-1.0, 5 bar, 519–543 K). By contrast, hydrocarbons such as methane were preferentially obtained on the catalysts prepared from Ru6, Ru3 and Co4 carbonyl clusters and provided lower CO conversion and poor selectivities for oxygenates. The RuCo bimetals are proposed to be associated with the selective formation of higher alcohols in CO hydrogenation.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1432-2242
    Schlagwort(e): Key words Oryza sativa ; Hybrid sterility ; Ste loci ; Molecular markers ; Hybrid rice breeding
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  Low-temperature-sensitive sterility (LTSS) has become one of the major obstacles in indica-japonica hybrid rice breeding. In this study, we determined, using RFLP markers, the genetic basis of LTSS in two populations derived from crosses between indica and japonica parents, the BC1F1 of 3037/02428//3037 and the F2 of 3037/02428. The fertility segregation in the two populations under low-temperature conditions was used as a measurement of the temperature sensitivity of the various genotypes in the populations. A RFLP survey of bulked extremes from the BC1F1 population identified three genomic regions, two on chromosome 1 and one on chromosome 12, that were likely to contain genes for LTSS (or Ste loci). One-way ANOVA and QTL analysis using a total of 19 markers from these three genomic regions resolved three Ste loci in the BC1F1 population and two Ste loci in the F2 population. On the basis of chromosomal location these loci were distinct from those governing wide-compatibility identified in previous studies. Two- and three-way ANOVA showed that these loci acted essentially independent of each other in conditioning LTSS. The main mode of gene action was an interaction between the indica and the japonica alleles within each locus. For each respective locus this resulted in a drastic fertility reduction in the heterozygote state relative to the homozygote state. The results have significant implications in indica-japonica hybrid rice breeding programs.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1432-2242
    Schlagwort(e): Key words Oryza sativa L ; Indica and japonica ; Hybrid sterility ; Mapping ; Rice breeding
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  The discovery of wide-compatibility varieties (WCVs) that are able to produce normal fertility hybrids when crossed both to indica and japonica rice has enabled the fertility barrier between indica and japonica subspecies to be broken and provided the possibility of developing inter-subspecific hybrids in rice breeding programs. However, a considerable variation in the fertility level of hybrids from the same WCV crossed to different varieties has often been observed. One hypothesis for this variable fertility is that additional genes are involved in hybrid fertility besides the wide-compatibility gene (WCG). To assess such a possibility, we performed a genome-wide analysis by assaying a large population from a three-way cross ‘02428’/‘Nanjing 11’//‘Balilla’ using a total of 171 RFLP probes detecting 191 polymorphic loci distributed throughout the entire rice linkage map. Our analysis recovered 3 loci conferring significant effects on hybrid fertility. The major locus on chromosome 6 coincided in chromosomal location with the previously identified S 5 locus, and the 2 minor loci that mapped to chromosomes 2 and 12, respectively, were apparently distinct from all previously reported hybrid sterility genes. Interaction between the indica and japonica alleles at each of the loci caused a reduction in hybrid fertility. The joint effect of the 2 minor loci could lead to partial sterility even in the presence of the WCG. The location of the S 5 locus on the molecular marker linkage map was determined to be approximately 1.0 cM from the RFLP locus R2349. This tight linkage will be useful for marker-aided transfer of the WCG in hybrid rice breeding and for map-based cloning.
    Materialart: Digitale Medien
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