Use of Monolploid Solanum phureja in Cell and Tissue Culture Techniques for Potato Improvement

Monoploid genotypes (2n = x = 12), derived by anther culture of a diplandrous genotype of Solanum phureja, a South-American diploid potato species, were examined for their utility in germplasm development. Nine monoploid genotypes and the diploid anther-donor plant were grown in photoperiod chambers at The Southeastern Plant Environment Laboratories (SEPEL) at North Carolina State University to examine the effect of photoperiod on tuber yield and to determine the variability for critical photoperiod for tuberization. Significant differences were found among the monoploid genotypes for total tuber weight and tuber number. Longer photoperiod treatments both decreased and delayed tuberization. Axillary tuber formation from single-node cuttings was used to estimate the onset of tuber induction and demonstrated variability among monoploid genotypes for critical photoperiod for tuberization. Leaf-disc culture of 24 monoploid genotypes yielded calli which regenerated plants from three genotypes. SDS-polyacrylamide gel electrophoresis of leaf extracts demonstrated variability among diploid and tetraploid calliclones of one monoploid genotype for total protein banding pattern. Absence of stainable pollen and lack of seed set after crosses to diploid species and tetraploid cultivars illustrated infertility among doubled (2n = 2x = 24) and twice doubled (2n = 4x = 48) monoploid-derived lines. Flow-cytometric analysis of pollen obtained from the diploid anther-donor genotype grown under three photoperiods at SEPEL yielded two populations of pollen based on propidium iodide staining of DNA. These populations corresponded to pollen separation based on size parameters alone, introducing the potential for flow sorting of pollen to increase seed set in 4x-2x crosses to tetraploid cultivars. Protoplast isolation from in vitro material and extraction of leaf nuclei both in vitro and in vivo were performed on the anther-donor plant, one of its antherderived monoploids, and a diploid and tetraploid plant derived from callus culture of the monoploid genotype. Flow-cytometric analysis of propidium-iodide stained cells and nuclei showed a greater ploidy stability for plant material grown in vitro and a limit to endopolyploidization imposed by initial ploidy level. Flow-cytometric analysis of .protoplast-derived nuclei from nine monoploid genotypes derived from anther culture of a single diploid genotype exhibited significant differences for 4C DNA content, but not for 1 C DNA content, indicating that ploidy stability, rather than monoploid status per se, is influenced by genotype

Influence of Hormonal Chemicals and Genotypes on Fruit Growth of Lycopersicon esculentum

The effects of hormonal chemicals and different genotypes on fruit growth of greenhouse-grown tomatoes ( Lycopersicon esculentum Mill.) were examined. Continuous root application of lOnM N6 -benzylaminopurine in Hoagland\u27s nutrient solution to tomato seedlings of \u27Fireball\u27 and \u27Red Cherry\u27 significantly delayed anthesis of \u27Fireball\u27, but not \u27Red Cherry\u27. Ovary diameter at anthesis, final fruit diameter, and fruit weight of both cultivars were unaffected. Irrespective of treatments, a significant positive correlation was obtained between ovary diameter at anthesis and final fruit diameter. A single foliar application of 0.25mM or 0.37mM 6-naphthoxyaceticacid (betaNOA) at the appearance of the first inflorescence of \u27Fireball\u27 significantly increased ovary diameter at anthesis, but had no effect on final fruit diameter. Flowers on the second inflorescence of tomato plants treated with 0.37mM betaNOA had smaller ovary sizes at anthesis than those of untreated plants. Application of 0.125mM betaNOA, and luM, lO~M, and lOOuM gibberellin A3 had no significant effect on ovary diameter at anthesis or final fruit diameter. A significant positive correlation was also shown between ovary diameter at anthesis and final fruit diameter of betaNOA treated plants. Among the twelve genotypes tested, significant correlations between ovary diameter at anthesis and final fruit diameter were found for \u27Fireball\u27 1 \u27Michigan/Ohio Hybrid\u27 1 and \u27New Yorker\u27. The remaining genotypes showed no significant correlations between ovary diameter at anthesis and final fruit diameter. The average ovary diameter at anthesis (of all the genotypes) was significantly correlated with final fruit diameter, fruit weight, and locule number