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- Author or Editor: Michael Marcotrigiano x
- HortScience x
Abstract
Some authorities place the genus Paulownia in the family Bignoniaceae, while others place it in the Scrophulariaceae, a closely related family (4). Paulownia tomentosa Steud., the empress or princess tree, originates in China. According to Hu (2), there appears to be no published record of an accurate introduction date into the United States, although it probably was introduced shortly after 1844. The species received an award of merit from the Royal Horticultural Society of London in 1934 (1). Because of its tolerance of poor soils and its rapid growth rate, it has become popular for strip mine reclamation (10). In addition, the wood of Paulownia is considered valuable, especially in Japan (9).
A teaching exercise that rapidly and inexpensively demonstrates the effects of leaf reduction on the rooting of stem cuttings is described. Coleus stem cuttings with whole leaves, half leaves, or no leaves are placed in sand on either misted or nonmisted greenhouse benches. Rooting response is recorded by ranking root systems by comparison to a diagram. A demonstration is also described that uses leafless cuttings cultured in vitro on solidified media containing a carbohydrate and/or auxin source. This demonstration gives students information that will help them speculate on the physiological reasons for the poor rooting response of leafless herbaceous cuttings.
Lycopersicon peruvianum is a wild species of tomato that exhibits gametophytic self-incompatibility (S), wherein the SI response is controlled by the genotype of the pollen. Cultivated tomato (L. esculentum) is a self-compatible species. Assisted by phenotypic markers, periclinal graft chimeras between these two species have been obtained. Fruit set analysis following breeding demonstrated that the available five chimeras (PPE, PEE, PEP, EPP, and EEP) are able to accept pollen from L. peruvianum, suggesting that there is a failure of the SI response. SI response is known to be dependent on S-locus associated proteins. These proteins are present in the style, which is mainly derived from the L1 and L2 layers of meristem. RNA analysis of the style tissue using a cloned S-locus cDNA as a probe showed that, except for EEP, all chimeras expressed the S-allele. This was also confirmed by SDS-PAGE analysis of stylar proteins that were present in variable amounts depending on the periclinal combination. Thus, the breakdown of SI is not associated with the lack of expression of the S-locus. Further work is being conducted to understand the nature of this breakdown.
In an effort to accelerate breeding programs and to study somaclonal variation, a micropropagation system was devised for cranberries (Vaccinium macrocarpon). Using a factorial design, explants taken from greenhouse grown plants were placed on Anderson's medium containing different concentrations of 2ip' GA3, and IBA, with 4 cultivars tested over 3 subcultures. In other experiments, explant source, macro and micro salt formulations, and rooting treatments, were studied. Optimal multiplication and shoot quality occurred when single node explants taken from greenhouse grown plants were placed on Anderson's media containing 150 uM 2iP, 1.0 uM IBA and no GA3. Histological examinations indicate that initial response is axillary bud proliferation but upon subculture adventitious shoot formation may be possible. Proliferated shoots could be rooted ex vitro in plug trays under plastic tents and without hormone treatments. Optimal rooting occurred under high light conditions in a 1:1 (v:v) peat:sand mix. Plants were easily transplanted into the field in spring and will be evaluated by comparison to conventionally propagated material.