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  • Author or Editor: Kenneth C. Sink x
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Lutein and zeaxanthin are becoming established as carotenoids beneficial for protection against common age-associated eye diseases. Thus, 15 potato (Solanum tuberosum subsp. tuberosum L.) breeding lines, cultivars Atlantic, Spunta, and Yukon Gold; and orange flesh OR-4 were surveyed for carotenoid profiles. Seven carotenoids, including violaxanthin, neoaxanthin, antheraxanthin, lutein, zeaxanthin, β-cryptoaxanthin, and β-carotene, were identified in the 19 genotypes. Violaxanthin and lutein were the prominent carotenoids detected in all genotypes studied. Neoaxanthin and antheraxanthin were found in 26% and 63% of the genotypes, respectively. β-Cryptoaxanthin, zeaxanthin, and β-carotene were found in only 5%, 10%, and 16% of the genotypes, respectively. Lutein varied from 19.8 to 119.0 μg·100 g-1 fresh weight across the 15 white- or yellow-flesh breeding lines. In contrast, zeaxanthin was detected at a low level in only one breeding line and at high level in OR-4. The three cultivars had profiles typical of yellow-flesh potatoes `Spunta' and `Yukon Gold'; while `Atlantic' had a typical white-flesh profile and a trace of zeaxanthin. The carotenoid baseline data established in this study provide information for activities to enhance potato for lutein and zeaxanthin.

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RAPD (Random Amplified Polymorphic DNA) is being utilized to construct a molecular genetic linkage map. The mapping population used is comprised of 65 individuals. Of the 240 decamer primers (Operon) tested to date, 50 polymorphic bands have been resolved. The 50 markers are divided into two groups according to the genotypes of the two parents. The first group is where the female parent is heterozygous and male parent is homozygous and it has 17 markers, while the second group, in which male parent is heterozygous and female parent is homozygous, has 33 markers. Analysis of the two groups by MAPMAKER indicated that two linkage groups are formed in the first group, and five linkage groups are formed in the second group. Sex type is controlled by the M locus. Genetic experiments have demonstrated that females are homogametic (mm) while male plants are heterogametic (Mm) for the sex locus. Two bulks of genomic DNA created by using 10 male and 10 female individuals in the population were screened to identify RAPD markers associated with the sex locus. RAPD marker OCP15-984 is closely linked with the M locus (7.6 cM).

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Abstract

The shoot apical meristem of the seedling and mature vegetative petunia exhibit no morphological differences in relation to double versus single floral genotypes. The vegetative meristem possesses a biseriate tunica and a radially patterned corpus.

The flower of the petunia develops directly from the apical meristem. The succession of flowers is accomplished by the lateral development of another meristem from the flank of the central meristem.

All floral appendages in the single flowered genotype dd are initiated acropetally. The petal and stamen primordia arise from a circular initial centripetal and adjacent to the sepal primordia. The floral initiation of the double flowering genotype D– differs from the single with an intense and random initiation of additional primordia over the surface of the receptacle. Differentiation of these primordia into petals or stamens appears to be determined by their position on the receptacle. The proliferation of petals and anthers caused by D results in a restriction of carpel and placental development, and hence, a malformed, nonfunctional pistil is usually produced. With the presence of the D allele, double flowers are always produced but the degree of doubleness appears to be a factor of gene dosage.

Open Access

Embryogenic callus from four asparagus genotypes (JG8, MD10, MD22, and 86SOM1) was initiated from micropropagated spears placed on semisolid LS medium containing 5 μM 2,4-D or 50 μM NAA, concomitantly. After three subcultures such cells were used to initiate suspensions in liquid medium of the same composition. The eight sets of suspensions were used as sources of protoplasts at two months of age and again at five months. Protoplasts were immobilized at 105/ml density in MS medium with 0.6% agarose and overlaid with liquid KM medium containing the auxin of the corresponding donor suspension or no hormones. Plating efficiencies were recorded at 14 days and ranged from 0% to 40% depending on the genotype, suspension medium, and inclusion or exclusion of hormones in the protoplast plating medium. All four genotypes were capable of forming somatic embryos directly from protoplasts; however, conversion was greatest from MD10 and MD22 derived cultures and occurred as rapidly as six weeks after initial protoplast culture.

Free access

Abstract

Aphrodite types of Rieger begonias are routinely propagated by terminal stem cuttings and the Schwabenland types by leaf-petiole cuttings (J. C. Mikkelsen, personal communication). The shoots and roots that arise at the base of the petiole of a leaf-petiole cutting of the Schwabenland types are of adventitious origin.

Open Access

Abstract

The pansy, Viola tricolor Hortensis, L. is a popular bedding plant, however, the problem of low seed set has hindered genetic studies, plant breeding efforts, and the production of Fl hybrids. Twenty-nine commercial inbred pansy lines were investigated cytologically to establish a possible relationship between chromosome number and pollen fertility. The somatic chromosome number of all lines studied was found to be 2n=48 and pollen fertility was above 90 percent. Preliminary hybridization investigations suggest the problem may be an incompatibility system.

Open Access

Abstract

Differences in bract abscission were found among several cultivars of poinsettia either intact or debladed in response to exogenously applied growth regulators. Indoleacetic acid (IAA) delayed the abscission of debladed petioles relative to its concentration, time, and point of application. Gibberellic acid or abscisic acid alone had no effect but interacted with IAA. Ethylene had no influence on abscission. No treatment accelerated the abscission rate of debladed petioles. There was no consistent modification of the relative differences among cultivars.

Open Access

Abstract

A study was made of the changes with aging in the level of endogenous auxin and the activity of IAA-oxidase in the bracts of two poinsettia cultivars. The auxin level decreased with time in both cultivars but faster in the poor keeper. The activity of the IAA-oxidase system and the level of hydrogen peroxide increased with aging. The auxin level could be related to the activity of IAA-oxidase, which in turn could be related to the appearance of new forms of peroxidase. A hypothesis is developed to explain differences in keeping quality among poinsettia cultivars based on changes in the level of endogenous auxin.

Open Access

Abstract

Leaf sections of a Petunia paradii x P. inflata somatic hybrid treated with griseofulvin (7-chloro-2’,4,6-trimethoxy-6’-methyl-spiro(benzofuran-2(3H), 1’-2 cyclohexene)-3, 4’dione) have been regenerated into whole plants. Of the regenerates, 5% expressed various degrees of leaf and flower abnormalities. About 80% of these abnormal types had chromosome numbers reduced from the pentaploid control level. It appears that the griseofulvin-induced chromosome instability may activate a type of position effect-variegation which causes both leaf and flower variegation.

Open Access

Abstract

“Asparagus decline” decreases production and kills Asparagus officinalis L. The principal pathogens involved in the decline are considered to be Fusarium oxysporum f. sp. asparagi Cohen and Heald (FOA) and F. moniliforme (Sheld.) emend. Synder and Hans. (FM). Three- to four-month-old plants of A. officinalis and three other asparagus species were inoculated in the greenhouse and evaluated for resistance to these Fusarium spp. Of the 90 A. officinalis accessions evaluated, two all-male cultivars, Lucullus 234 and 328, received the lowest disease ratings to FOA and FM. Asparagus densiflorus ‘Sprengeri’ and ‘Myersii’ received the lowest disease ratings of the other asparagus species tested. Of the total 95 germplasm entries evaluated, 39% were more resistant than the susceptible control ‘UC 157’, 44% were rated similiar in susceptibility, and 17% were more susceptible. Accessions responded similiarly to both Fusarium spp.

Open Access