Inheritance of a twisted pod characteristic, in which bean pods develop with a twist that sometimes exceeds 360°, was studied in crosses between round-podded green bean cultivars. In crosses between `Oregon 91G' (normal) or `Oregon 54' (normal) and OSU 5256-1 (twisted), the F1 was normal. Segregation in F2 populations, tested over a 4-year period and including 4,995 plants, clearly fit a 3 normal: 1 twisted ratio. All plants of backcrosses of the F, to the normal parent were normal and backcrosses of the F1 to the twisted parent segregated 1 normal: 1 twisted. The ratios observed indicated that twisted pods are conditioned by a single recessive gene for which the symbol tw is proposed.
In crosses between stringless and stringy podded pea cultivars, all plants of the F1 and backcross to the stringy parent had stringy pods. F2 ratios varied widely among crosses, and populations always had more stringy plants than expected, based on a single locus. The ratio of nonsegregating (stringy): segregating F3 families derived from stringy F2 plants fit a single-gene hypothesis in half of the crosses. Backcrosses of F1 to the stringless parent fit the expected 1:1 ratio when the pollen parent was stringless, but the reciprocal backcrosses showed a deficiency of stringless plants, suggesting that poor competitive ability of pollen bearing the stringless factor was the reason for deficiencies of stringless plants. It is concluded that stringlessness is controlled by a single recessive gene for which the designation sin-2 is proposed. A reduction in pod size, plant height, and number of wrinkled seed segregates was associated with stringlessness.
Immature white seedcoat (IW), consisting of reduced green color in immature seedcoats and early development of white color in white seeded cultivars of Phaseolus vulgaris, is described. IW was found in 9 of 66 commercial cultivars. It occurs irrespective of mature seedcoat colors, pod pigmentation, or wax vs. green pod color. Genetic analyses of progenies from 6 crosses indicated IW is conditioned by a single recessive gene which is not linked with the P locus for mature seedcoat color or with Y for green vs. wax pod. The gene designation iw is proposed for immature white seedcoat.
‘Gallatin 50’, a bush cultivar not of ‘Blue Lake’ background, and ‘Oregon 1604’, a bush cultivar of ‘Blue Lake’ type, were crossed with distortion susceptible lines of ‘Blue Lake’ type. Environment affected distortion expression; the best expression was obtained in the greenhouse while expression was much reduced in the field. Ratios obtained suggested distortion is primarily controlled by a single dominant gene, designated Ld. ‘Oregon 1604’ carries the recessive allele for normal. ‘Gallatin 50’ carries a major dominant gene, designated Ds, that supresses the expression of the dominant gene Ld for leaf distortion tendency. Results also suggested that modifying factors are involved and are responsible for levels of susceptibility among parents and progenies. Additional crosses between susceptible lines showing severe to mild distortion indicated that these lines carried the same major genes for distortion, but differed in modifying factors.
The inheritance of a tendency to set parthenocarpic fruit in tomato (Lycopersicon esculentum Mill.) line Oregon T5-4 (T5) was studied in the field in crosses with 3 normal, seeded cultivars. F1, F2, and backcross data indicated that the parthenocarpic tendency in T5 is recessive. F2 data fit a 9 seeded : 7 seedless ratio, indicating that normal seediness requires 2 complimentary dominant genes. Parthenocarpic plants were earlier than seeded plants. Early ripening in T5 crosses resulted in most instances from a reduced period of time from first flower to first ripe fruit, and not from early flowering. The F2 from a cross of T5 with ‘Severianin’, an unrelated parthenocarpic cultivar, approached a theoretical 27 seeded : 37 seedless for 3 complimentary gene pairs and demonstrated that parthenocarpic tendency is determined by different factors in these 2 parents.
Broccoli cultivars differed greatly in their tendency for premature heading and total loss from this factor and from culls. Per cent premature heads was increased by the use of large transplant sizes in the 9 cultivars studied; total loss was generally, but less, affected in the same way. Significant interactions were found between varieties and plant size in both premature heading and total loss. Transplanting date affected premature heading and total loss in one of the 2 years it was considered. Nitrogen levels, included in one experiment, did not cause significant effects.
Pea cultivars may be severely or mildly affected (susceptible), or completely symptomless (resistant) when infected with an Oregon isolate of PSV. Infected plants of susceptible and resistant cultivars contained substantial virus concentrations which were not consistently related to symptom severity. The severity of symptoms in inoculated plants and the numbers of plants showing symptoms differed in various tests, apparently in response to changes in environment and the virulence of the virus. When apparent maximum symptom expression occurred, it was shown that the highest degree of resistance was due to a single recessive gene. Deviations from the expected ratio of 3 susceptible: 1 resistant (symptomless) were always the result of excess symptomless plants, probably because of combinations of effects of the environment, modifying genes from one or both parents, and in the later phases of the study, a reduced virus virulence. Observations and limited tests suggested that symptom development was promoted by conditions which were unfavorable for optimum plant growth.
Commercial pea (Pisum sativum L.) cultivars, plant introduction (PI) lines, and Oregon State Univ. (OSU) breeding lines were tested for resistance to pathotype P2 (lentil strain) and pathotype P1 (type strain) of pea seedborne mosaic virus (PSbMV) and to bean yellow mosaic virus (BYMV) to assess the relative proportion of resistant and susceptible pea genotypes. Of the 161 commercial cultivars tested, 117 (73%) were resistant and 44 were susceptible to PSbMV-P2. Of these PSbMV-P2-resistant cultivars, 115 were tested for resistance to BYMV and all were resistant. Of the 44 PSbMV-P2-susceptible cultivars, 43 were tested for BYMV susceptibility and all were infected except two, `Quincy' and `Avon', both of which were susceptible to a BYMV isolate in another laboratory. Of 138 commercial cultivars inoculated with PSbMV-P1, all were susceptible. All PI lines and OSU breeding lines that were resistant to PSbMV-P1 were resistant also to PSbMV-P2. The high percentage of commercial cultivars resistant to PSbMV-P2 was probably attributable to the close linkage of genes sbm-2 and mo and the widespread use by breeders of BYMV-resistant `Perfection' and `Dark Skin Perfection' in developing new pea cultivars. Segregation ratios in progenies of three separate crosses between PSbMV-P2-resistant and PSbMV-P2-susceptible cultivars closely fit the expected 3 susceptible: 1 resistant ratio expected for resistance conferred by a single recessive gene.
The inheritance of resistance in beans (Phaseolus vulgaris L.) to typical bean yellow mosaic virus (BYMV) was compared to the severe strain (BYMV-S). When F3 families of BYMV resistant ‘Great Northern UI 31’ (GN31) × susceptible ‘Dwarf Horticultural’ were tested for resistance to each virus strain, occurrence of homozygous resistant families was conditioned by 3 recessive genes for BYMV and 2 recessive genes for BYMV-S. Of the 132 families tested, 122 were susceptible to both BYMV and BYMV-S, 6 were resistant to BYMV-S and susceptible to BYMV, 4 were susceptible to BYMV-S and resistant to BYMV, and none were resistant to both. This ratio closely fits a theoretical 945:63:15:1, indicating that resistance to BYMV and to BYMV-S are inheritied independently. When GN31 was crossed with breeding line Sl-5, also resistant to both virus strains, F3 progenies included families susceptible to one or both virus strains, possibly through the complimentary interaction of modifiers. Chi square tests indicated independent inheritance of resistances to BYMV and BYMV-S in GN31 × S1-5 progenies.
Inheritance of the volatile flavor component l-octen-3-ol in ‘OSU 58-110’ × ‘Bush Romano FM-14’ was determined, using gas-liquid chromatographic technique with gas-entrainment on-column trapping. The low concentration of l-octen-3-ol characteristic of ‘58-110’ was dominant in the F1, F2 and backcrosses. The range of concentration in each parent and the F1 was about 80 ppb. The concentration in the F1 was nearly identical to that of the low parent. F2 and backcross data were continuous over a wider range of concentration than the parents or F1. A definite bimodal distribution was not apparent.