Search Results
Abstract
Fourteen tetraploid seedling populations of blackberry (Rubus sp.), representing quadruplex, (TTTT), triplex (TTTt), duplex (TTtt), simplex (Tttt), and nulliplex (tttt) genotypes for the major gene conferring thorniness, were evaluated for segregation of cane thorn density and cotyledonary gland number. Comparisons of seedling distribution curves, means and variances of segregating and non-segregating populations did not show a gene dose effect on gland and thorn occurrence. Inheritance of cotyledonary glands and cane thorns in blackberry was qualitative with the density of glands and thorns apparently controlled by several modifying genes.
Abstract
Customer harvest (PYO) of research plots at University of Illinois and University of Arkansas research stations began in the late 1960s when it became difficult to harvest extensive research plots. Similar methods were developed independently for customer harvest at both locations. Initially we invited faculty, staff, their wives, and eventually other local people to pick strawberries, blackberries, and blueberries. We obtained yield records and the customers paid for the fruit. Data were collected to evaluate cultivars and advanced breeding selections of strawberries, blueberries, and blackberries.
Abstract
Time of flower bud initiation was determined for nine peach [Prunus persica (L.) Batsch.] cultivars, three in each of three chilling requirement groups (<500 hr, 500-750 hr, and 800-1050 hr below 7.2°C). Based on morphology of the apical dome, the first visible signs of flower bud initiation of all cultivars occurred between 15 July and 8 Aug. 1984, and between 1 and 20 July 1985. The earlier initiation period in 1985 may have been promoted by drought stress. Although significant differences occurred in time of flower bud initiation among chilling requirement groups in both years, they were not consistent from year to year, indicating that chilling requirement is not strongly associated with time of flower bud initiation. The rate of morphological development of flower primordia was not associated with earliness of flower bud initiation. ‘Diamante’, while early in flower bud initiation, showed a slow rate of subsequent flower development. No relationship was found between time of flower initiation and either time of bloom or time of fruit ripening of the cultivars.
Abstract
Chinese chestnut, Castanea mollissima Bl., is resistant to chestnut blight incited by Endothia parasitica Murr., a disease which eliminated almost all American chestnuts, C. dentata (Marsh) Borkh. Two or three nuts are usually present in each bur of Chinese chestnuts; the better ones are excellent in quality. Chinese chestnuts grow over a large part of the United States; however, they seem best adapted to the southeastern region.
Abstract
In the Cultivar and Germplasm Release article “‘Allgold’ and ‘Goldilocks’ Peaches” by J.N. Moore, Roy C. Rom, Stanley A. Brown, and William A. Sistrunk [HortScience 19(6):891–892, 1984], the captions of Figures 2 and 3 were reversed. The selection test numbers given in the text for these cultivars (‘Allgold’ = A-142; ‘Goldilocks’ = A-15) are correct.
Random amplified polymorphic DNA (RAPD) may have utility as genetic markers facilitating selection in ginseng crop improvement. This experiment determined chemical buffer and root tissue-type combinations that yield repeatable bands. The results allow further experiments using RAPD markers for estimating the genetic distance between ginseng landraces, selection for crop improvement, and extensive fingerprinting for use in determining the origin of tissue samples. This experiment determined mean band yields for all combinations of dry, fresh, and powdered root with cetyltrimethylammonium bromide, potassium/sodium ethyl xanthogenate, and urea buffers. The buffers were applied in replication to the tissue-types with other extraction protocol factors constant. Replications were amplified four times with four different primers using constant PCR and agarose gel electrophoretic protocols. Distinct bands were counted in each replication, and the summation of the replication repeats considered an observation. Least squares means for several response variables were analyzed. The most significant difference found was between buffers. The buffers ctab and urea were productive, and the pex was not. Significant difference was found when buffers were crossed with tissue. The applications of urea to fresh root, ctab to dry root, urea to dry root, and ctab to powdered root were productive. Based on these results we conclude 1) urea and ctab are productive when applied to all tissue-types, 2) dry root, which is easily collected and stored, yields sufficient DNA for analysis, and 3) powdered root, often the form of commercial products that might be tested for genetic origin, will yield sufficient DNA for analysis.
The visual appearance of mangos is a primary factor in determining consumer acceptance and sale, similar to other fruit and vegetable commodities. Even if the appeal of visual appearance is based on consumer perception rather than on established quality factors, breeders must usually select within the range of acceptance, at least in some countries. Mango selection using multiyear breeding programs is slowly replacing the former method by which most earlier cultivars were selected, namely from chance seedlings either from planned or unplanned crosses. The knowledge of heritability of traits as they are controlled by genetics and experimental design and the effects and interaction of these two sets of factors on achieved gain have become more critical. The use of portable colorimeters has been shown to give repeatable scores in a quantitative, three-dimensional space for fruits and vegetables. In this experiment, we calculated broad-sense heritability estimates for five color traits, three morphological fruit traits, and one disease resistance trait (anthracnose expressed on the fruit). Estimates were found to be relatively high, indicating good potential for improvement through breeding. For nearly all traits measured, variance within families was greater than that among families, illustrating the likely importance of heterozygosity, dominance, and epistasis in these crosses. The careful estimation of heritability and repeatability will help prioritize and increase the efficiency of trait improvement as breeding methods become more sophisticated and competition for funding increases.
Methods to increase transformation efficiency and yields of transgenic Anthurium andraeanum Linden ex. André hybrids were sought while effecting gene transfer for resistance to the two most important pests, bacterial blight (Xanthomonas axonopodis pv. dieffenbachiae) and nematodes (Radopholus similis and Meloidogyne javanica). Differentiated explant tissues, embryogenic calli, and comingled mixtures of the two were transformed with binary DNA plasmid constructs that contained a neomycin phosphotransferase II (nptII) selection gene with a nos promoter and terminator. Explants included ≈1-cm long laminae, petioles, internodes, nodes, and root sections from light- and dark-grown in vitro plants. Bacterial blight resistance genes were NPR1 from Arabidopsis, attacin from Hyalophora cecropia, and T4 lysozyme from the T4 bacteriophage. For nematode resistance, rice cystatin and cowpea trypsin inhibitor genes were used. Cocultivation with Agrobacterium tumefaciens strains EHA105, AGLØ, and LBA4404 ranged from 2 to 14 days. Over 700 independent, putatively transformed lines were selected with 5 and 20 mg·L−1 geneticin (G418) for cultivars Midori and Marian Seefurth, respectively. Putative transgenic lines were selected 1 to 11.5 months, but on average 5.2 to 8.4 months, after cocultivation depending on the tissue type transformed. Significantly more embryogenic calli (one line per 5 mg calli) produced transgenic lines than did explants (one line per 143 mg explants) (P < 0.004) from ≈30 mg of tissue. Calli grew selectively from all explant types, but the type of explant from which each selection was made was not recorded because root, internode, and petiole explants were difficult to discern by the time calli developed. Shoots formed 3 months after calli were transferred to light. Non-transgenic control and transgenic ‘Marian Seefurth’ formed flower buds in the greenhouse ≈28 months after cocultivation. The plants resembled commercially grown plants from a private nursery. No non-transformed escapes were detected among the selections screened for NPTII by enzyme-linked immunosorbent assay and polymerase chain reaction (PCR). The selections were positive for transgenes as assayed by PCR and Southern hybridizations. Southern blots showed single-copy insertions of the NPR1 regulatory gene. The ability to produce large quantities of independent transgenic lines from embryogenic calli in a relatively short time period should enable researchers to evaluate the effectiveness of any transgene by screening numerous anthurium lines for improved performance.