Single Dominant Allele Research Articles

The inheritance of drug resistance and compatibility type in Phytophthora drechsleri

SummaryMethods have been developed for the selection of mutants resistant to p-fluorophenylalanine, chloramphenicol and actidione. Resistance to p-fluorophenylalanine and to chloramphenicol was inherited as if determined in each case by a single dominant allele present in diploid somatic nuclei. Inheritance of mating type was anomalous in crosses involving drug-resistant mutants. Presumptive mating-type heterokaryons were generated in a few per cent of sexual progeny from a wild-type cross.

Inheritance of Resistance to Downy Mildew (Bremia Lactucae Reg.) in Lettuce1

Abstract The inheritance of resistance to California race(s) of downy mildew in lettuce was studied in cvs. Bourguignonne, Meikoningin, Proeftuin’s Blackpool, Red Salad Bowl, Salad Trim, Ventura, and PI 164937. Resistance in cvs. Bourguignonne, Red Salad Bowl, and Salad Trim is conferred by a single dominant allele. This is the same allele found in resistant cvs. Calicel, Calmar, E-4, Imperial 410, Valrio, Valtemp, and Valverde, and is derived from resistant PI 91532. Resistance in ‘Meikoningin’ is controlled by a single dominant allele different from the one derived from PI 91532. Allelism tests indicate that the 2 alleles are independently inherited. ‘Proeftuin’s Blackpool’ and ‘Ventura’ each have 2 dominant alleles for resistance that are different from the single dominant allele derived from PI 91532. Allelism tests of ‘Proeftuin’s Blackpool’ and ‘Ventura’ indicate resistance is conferred by the same 2 dominant alleles. The 2 alleles in cvs. Proeftuin’s Blackpool or Ventura and the single allele derived from PI 91532 are independently inherited. Resistance in PI 164937 is conferred by 2 dominant alleles, one of which is the same as the single dominant allele derived from PI 91532.

Inheritance and Linkage of Turnip Mosaic Virus and Downy Mildew (Bremia lactucae) Reaction in Lactuca serriola1

Abstract Data for resistance in Lactuca serriola L. to turnip mosaic virus (TuMV) and downy mildew were obtained from 5 F2 progenies of crosses between TuMV-susceptible, mildew-resistant, and TuMV-resistant, mildew-susceptible parents. The F1 progeny were TuMV and mildew-resistant. Of 1,103 F2 plants assayed 823 were TuMV-resistant and 280 TuMV-susceptible. A total of 834 mildew-resistant plants were observed, and 269 mildew-susceptible. Resistance to TuMV and mildew are each controlled by a single dominant allele, designated Tu and Dm, respectively. The TuMV gene, Tu tu, is linked with the mildew gene, Dm dm. In the repulsion phase, the crossover value was 12.0% ± 2.9. F2 progenies of crosses between TuMV-susceptible, mildew-resistant L. serriola and TuMV-susceptible, mildew-resistant L. sativa cv. ‘Calmar’ or ‘Imperial 410’, and crosses among cv. ‘Calmar’, ‘Imperial 410’, and ‘E-4’, indicated they possessed the same dominant allele for mildew-resistance, and the same recessive allele for TuMV-susceptibility.

INHERITANCE OF RESISTANCE TO INFLUENZA VIRUS IN MICE.

SummaryF1, F2, first, second, and third backcross generation mice resulting from crosses of A2G with A, and F1 F2 and first backcross generation mice resulting from crosses of A2G with C3H were challenged with neurotropic influenza A virus, strain NWS. The results were compatible with the hypothesis that a single dominant autosomal allele was responsible for resistance to the virus. The symbol Mx (myxovirus-resistant) is tentatively proposed for the allele involved.

Studies on the sex expression of flowers in Cucumis Melo L. (I)

Experiments have been continued to investigate the sex expression in Cucumis Melo L. In the present paper, the structure of flower and the inheritance of andromonoeciousness versus monoeciousness are described, and the result of comparison as regards function of pollen from either hermaphroditic or staminate flower is presented. The andromonoe-cious plant used in the experiment was commercial variety Earl's Favourite which represents C. Melo L, var. reticulatus, and for the monoecious plant No. 111 and No. 981, collected in Afghanistan and Pakistan by the Japanese expedition in 1955 were used, of which No. 111 is believed to belong to the snake melon, C. Melo L. var. fLexuosus (Fig. 1). The results obtained are summarized as followes. 1. The hermaphroditic flower on andromoneci-ous plant bore the pistil and the stamens filled with pollen, while the pistillate flower on monoe-cious plant bore the pistil and the rudimentary stamens (Fig. 3, 4). 2. Though there was a fare occurrence of the andromonoecious plant bearing pistillate flower and of the monoecious plant bearing hermaphroditic flower, it was confirmed that the monoeciousness differed from the andromonoeciousness in a single dominant allele (Table 1. 2). 3. Pollen grains of the hermaphroditic flower as well as those of the staminate flower within the same vine germinated on the artificial media (1 agar, 5% sucrose and pH 6. 5) in different degree. The difference of germination percentage of the pollen of hermaphroditic and staminate flower was significant at 5 per cent level, i.e. 75.8 per cent and 66. 2 per cent respectively after one hour of culture. No significant difference was shown in the elongation of pollen tubes, and moreover, the rate of normal pollen was as high as 95 per cent or more in either hermaphroditic or staminate flower (Table 3). 4. Either through the intra self pollination or through the neighbour pollination with pollen of staminate flower within the same vine, the yield and the market value of the mature fruit from hermaphroditic flower were the same. Comparing the character of hermaphroditic flower with those of staminate flower, no significant difference was found with regards the function of pollen, i.e. the rate of fruit setting, the number of germinable seed, and the weight of fruit or seed. From the results, it is suggested that the intra self pollination on hermaphroditic flower facilitates practical procedure of pollination, with an advantage of securing the strict inbred seed.