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  • Genetic analysis  (2)
  • Restriction fragment length polymorphism (RFLP)  (2)
  • 1
    ISSN: 1432-2242
    Keywords: Key words Common wild rice ; Cultivated rice ; Evolution ; Genetic analysis ; Molecular marker
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Domesticated rice differs from the wild progenitor in large arrays of morphological and physiological traits. The present study was conducted to identify the genetic factors controlling the differences between cultivated rice and its wild progenitor, with the intention to assess the genetic basis of the changes associated with the processes of rice domestication. A total of 19 traits, including seven qualitative and 12 quantitative traits, that are related to domestication were scored in an F2 population from a cross between a variety of the Asian cultivated rice (Oryza sativa) and an accession of the common wild rice (O. rufipogon). Loci controlling the inheritance of these traits were determined by making use of a molecular linkage map consisting of 348 molecular-marker loci (313 RFLPs, 12 SSRs and 23 AFLPs) based on this F2 population. All seven qualitative traits were each controlled by a single Mendelian locus. Analysis of the 12 quantitative traits resolved a total of 44 putative QTLs with an average of 3.7 QTLs per trait. The amount of variation explained by individual QTLs ranged from a low of 6.9% to a high of 59.8%, and many of the QTLs accounted for more than 20% of the variation. Thus, genes of both major and minor effect were involved in the differences between wild and cultivated rice. The results also showed that most of the genetic factors (qualitative or QTLs) controlling the domestication-related traits were concentrated in a few chromosomal blocks. Such a clustered distribution of the genes may provide explanations for the genetic basis of the “domestication syndrome” observed in evolutionary studies and also for the “linkage drag” that occurs in many breeding programs. The information on the genetic basis of some desirable traits possessed by the wild parent may also be useful for facilitating the utilization of these traits in rice-breeding programs.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 88 (1994), S. 733-740 
    ISSN: 1432-2242
    Keywords: Restriction fragment length polymorphism (RFLP) ; Hordeum vulgare ; Quantitative resistance ; Erysiphe graminis f. sp.hordei ; Diallel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Powdery mildew, caused byEryisphe graminis f. sp.hordei, is one of the most important diseases of barley (Hordeum vulgare). A number of loci conditioning resistance to this disease have been reported previously. The objective of this study was to use molecular markers to identify chromosomal regions containing genes for powdery mildew resistance and to estimate the resistance effect of each locus. A set of 28 F1 hybrids and eight parental lines from a barley diallel study was inoculated with each of five isolates ofE. graminis. The parents were surveyed for restriction fragment length polymorphisms (RFLPs) at 84 marker loci that cover about 1100 cM of the barley genome. The RFLP genotypes of the F1s were deduced from those of the parents. A total of 27 loci, distributed on six of the seven barley chromosomes, detected significant resistance effects to at least one of the five isolates. Almost all the chromosomal regions previously reported to carry genes for powdery mildew resistance were detected, plus the possible existence of 1 additional locus on chromosome 7. The analysis indicated that additive genetic effects are the most important component in conditioning powdery mildew resistance. However, there is also a considerable amount of dominance effects at most loci, and even overdominance is likely to be present at a number of loci. These results suggest that quantitative differences are likely to exist among alleles even at loci which are considered to carry major genes for resistance, and minor effects may be prevalent in cultivars that are not known to carry major genes for resistance.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 95 (1997), S. 112-118 
    ISSN: 1432-2242
    Keywords: Key words Diallel cross ; Hybrid rice ; Oryza sativa ; Restriction fragment length polymorphism (RFLP) ; Simple sequence repeat (SSR)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The partial sterility of hybrids between the indica and japonica rice subspecies of Asian cultivated rice is a serious constraint for utilizing inter-subspecific heterosis in hybrid rice breeding. In this study, we have investigated the relationship between molecular-marker polymorphism and indica-japonica hybrid fertility using a diallel set involving 20 rice accessions including 9 indica and 11 japonica varieties. Spikelet fertility of the resulting 190 F1s and their parents was examined in a replicated field trial. Intra-subspecific hybrids showed much higher spikelet fertility than inter-subspecific hybrids except in crosses involving wide-compatibility varieties. The parents were surveyed for DNA polymorphism using 96 RFLP and ten SSR markers, which revealed extensive genetic differentiation between indica and japonica varieties. A large number of markers detected highly significant effects on hybrid fertility. The chromosomal locations for many of the positive markers coincided well with previously identified loci for hybrid sterility. The correlation between hybrid fertility and parental distance was low in both intra- and inter-subspecific crosses. The results suggest that the genetic basis of indica-japonica hybrid sterility is complex. It is the qualitative, rather than the quantitative, difference between the parents that determines the fertility of hybrids.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 97 (1998), S. 407-412 
    ISSN: 1432-2242
    Keywords: Key words Oryza sativa L. ; Indica-japonica cross ; Hybrid sterility ; Molecular marker ; Genetic analysis ; Epistasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Wide-compatibility varieties (WCVs) are a special class of rice germplasm that is able to produce fertile hybrids when crossed to both indica and japonica rice varieties. WCVs may differ greatly in their spectrum and level of compatibility. The objective of this study was to determine the genetic basis of wide-compatibility conferred by ‘Dular’, a landrace variety from India that has demonstrated a high level of wide-compatibility in previous studies with a broad range of indica and japonica varieties. A three-way cross (‘Balilla/Dular//Nanjing 11’) was made and the resulting F1 population evaluated in the field for spikelet fertility. A total of 235 plants from this population was assayed individually for restriction fragment length polymorphisms (RFLPs) at 159 marker loci covering the entire rice genome at regular intervals. Quantitative trait locus (QTL) analysis identified 5 loci, located on chromosomes 1, 3, 5, 6 and 8, as having significant effects on hybrid fertility, which jointly explained 55.5% of the fertility variation in this population. The QTL on chromosome 5 ( f5) showed the largest effect on hybrid fertility, followed by those on chromosomes 6 ( f6), 3 ( f3) and 1 ( f1), with the one on chromosome 8 ( f8) having the smallest effect. Genotypes each composed of an allele from ‘Dular’ and an allele from ‘Nanjing 11’ at four ( f3, f5, f6 and f8) of the five QTLs contributed to the increase of fertility in the population. In contrast, the genotype composed of alleles from ‘Balilla’ and ‘Nanjing 11’ at the fifth locus ( f1) was in the direction of increasing fertility. Analysis of variance using marker genotypes at the five QTLs as the groups detected two interactions involving four of the five loci, a 2-locus interaction between f5 and f8 and a 3-locus interaction among f3, f5 and f6. The level of hybrid fertility is the result of complex interactions among these loci. The implication of the present findings in the utilization of the wide-compatibility of ‘Dular’ in rice breeding programs is also discussed.
    Type of Medium: Electronic Resource
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