Zucchini yellow mosaic virus (ZYMV), a potyvirus, can cause major losses in cucurbit crops. With the goal of genetically engineering resistance to this disease we have engineered the ZYMV coat protein gene into a plant expression vector. The complete coat protein coding sequence, or the conserved core portion of the capsid gene, was attached to the 5' untranslated region of tobacco etch virus (TEV) in the pTL37 vector (Carrington et al., 1987, Nucl. Acid Res. 15:10066) The capsid constructs were successfully expressed by in vitro transcription and translation systems as verified by SDS-PAGE and ZYMV coat protein antibody. The constructs were then subcloned using polymerase chain reaction and attached to the CaMV 35 S transcriptional promoter on the CIBA-GEIGY pCIB710 plasmid. The constructs containing the CaMV 35S promoter, the 5' untranslated leader of TEV, and ZYMV coat protein sequences were then put between the Agrobacterium tumefaciens left and right borders in the pCIB10 vector and transferred to A. tumefaciens strain LBA4404 by triparental mating. These vectors are now being used to transform muskmelon and cucumber; resultant transgenic plants will be tested for ZYMV coat protein expression.
Three classes of crosses using four genotypes of V. riparia (wild Riverbank grape) as maternal parents were evaluated for evidence of reproductive expression of genetic incongruity. The classes were: I V. riparia x V. vinifera cultivars (European domesticated grape); II V. riparia x French Hybrids (complex interspecific hybrids); III V. riparia x V. riparia. Percent fruit set and seeds per berry were recorded for two years. If incongruity is a factor in interspecific grape crosses, then the values for these traits would be expected to be lower in classes I and II than in class III. Analysis of variance indicated significant differences for some half-sib families. Fruit and seed set were lower in classes I and II than in class III, suggesting that incongruity is operative in wide grape crosses. In the process of creating French hybrids, genomes of several species came together over generations of hybridization. In concert with selection for fertility, repeated interspecific genomic exposure would be expected to have ameliorated the effects of initial incongruity between American species and V. vinifera, increasing their value as genetic bridges in breeding programs.
Abstract
A system was developed to transform walnut cultivars using the natural gene transfer system of Agrobacterium tumefaciens. We report the infection of English walnut (Juglans regia L.), northern California black walnut (Juglans hindsii), and their F1 hybrid ‘Paradox’ with A. tumefaciens carrying various recombinant derivatives of the tumor-inducing (Ti) plasmids, pTiA6 and pTiB6S3. The three walnut species, each represented by a single micropropagated clone, were found to be equally susceptible to Agrobacterium-induced tumor formation in vitro. Stable lines were established from tumors induced on each clone, and, unlike normal stem callus, these tumor cells grew rapidly in culture media without exogenous plant hormones. High-voltage paper electrophoretic analysis revealed the presence of opines in the walnut tumor tissue. The presence of a foreign gene was demonstrated by expression of a chimeric bacterial gene that encodes resistance to the antibiotic kanamycin, and also by the presence of foreign DNA sequences in genomic DNA isolated from tumors.
Abstract
The presence of sporulating lesions on seedlings inoculated with the apple scab fungus in the greenhouse was the best criterion for discarding susceptible individuals, and provided a means of selecting other factors for resistance in addition to the Vf gene.
Short photoperiods (8 hr) and low light intensities (1000 ft-c) significantly reduced the percentage of resistant seedlings. This emphasized the importance of growing the seedlings under uniform conditions.
Progenies from crosses of resistant by susceptible parents (Vfvf × vfvf) were grown under various controlled regimes of light, temperature, and humidity. Inoculation with the scab fungus resulted in significantly different percentages of resistant seedlings, indicating genetic differences in resistance between these progenies. When inoculation results of progenies of susceptible varieties were summarized, the percentages of resistant seedlings varied with the observed susceptibilities of the parents. These genetic differences should be taken into consideration in a breeding program.
, this transcription factor complex regulates the expression of multiple target genes that determine epidermal cell specialization in plants ( Ramsay and Glover, 2005 ). The role of the MYC, MYB, WD40 complex in determining genetic epistasis and the
. Understanding the molecular basis for urushiol biosynthesis and urushiol chemical ecology will require a variety of molecular genetic methods, all of which require the introduction and expression of recombinant DNA in poison ivy plant cells and tissues. The
anthocyanin-related Myb gene expression between P. schilleriana (solid purple) and P. amabilis (albescent phenotype) are between genetically different species. Neither an albescent P. schilleriana nor a solid purple P. amabilis exist. Even though
regulatory mechanism. These results suggest that while the M locus may encode the F3′H gene, another gene or genes (unaccounted for by the genetic model) may encode a transcription factor(s) that regulates the expression of F3′H . These transcription
, green foliage) and 06C59 (anthocyanin pigmented: purple flowers, black fruit, black leaves). To determine the genetic basis for tissue-specific pigmentation, we evaluated the expression of anthocyanin biosynthetic ( Chs , Dfr , and Ans ) and
less is known about the genetic mechanisms that regulate flowering in SD plants, such as soybean ( Glycine max ), rice ( Oryza sativa) , and maize ( Zea mays ), among others; however, some progress has been made in such species through genetic analyses