Several procedures were tested in development of a gene transfer protocol for anthurium. Etiolated internode segments of anthurium cultivars `Rudolph' and `UH1060' were co-cultured with Agrobacterium tumefaciens LBA4404 carrying the chimeric genes neo, for antibiotic resistance, and att encoding antibacterial attacin. Assays of genomic DNA and RNA from kanamycin-resistant `Rudolph' and DNA from `UH1060' plantlets, recovered as soon as 1 year after culture on selection media, indicated the presence of introduced genes, including neo and att, and transcription of att. Western analysis confirmed the expression of attacin protein in calli induced from laminae of regenerated kanamycinresistant `Rudolph' plantlets. Use of tobacco nurse cells during co-cultivation of internodes with Agrobacterium did not increase recovery of shoots under the regeneration conditions used. Improvements in culture and antibiotic selection conditions during plant development are suggested.
Fure-Chyi Chen and Adelheid R. Kuehnle
Adelheid R. Kuehnle, Fure-Chyi Chen and Nellie Sugi
Bacterial diseases continue to plague ornamental crops, Genetic resistance offers one way to manage disease; combined with use of indexed propagules and sanitation, it can be a powerful control. Classical breeding offers some genetic solutions. Introgression, by genetic engineering, of antibacterial genes derived from the Cecropiamoth is a second breeding approach which appears promising in other horticultural crops. A case study for control of Xanthomonas, species of which severely limit geranium, anthurium, and other ornamental production, is given for anthurium. Transgenic anthurium plants expressing or containing antibacterial genes coding for the antibacterial peptides Attacin, P13 and T4 lysozymes, and the modified cecropins Shiva and SB37 were produced and challenged with bacteria. Juvenile and adult plants showed various degrees of tolerance to bacterial blight. The implications of this approach to bacterial disease control in various ornamental cropping systems will be discussed.
Pablo Bolaños-Villegas, Shih-Wen Chin and Fure-Chyi Chen
The development of new cultivars in Doritaenopsis Guillaum. & Lami orchids is often hindered by factors such as low seed count in hybrids. Cytological study may offer the ability to develop new hybrids by revealing cultivars with good chromosome pairing and high pollen viability, which are somewhat difficult to obtain under current breeding programs. Cross pollination, pollen viability, and chromosomal behavior during meiosis were analyzed to reveal the relation between seed fertility and capsule set in Doritaenopsis hybrids. The number of mature capsules harvested and their relative seed content were used as indices of crossing availability. The results of meiosis were evaluated according to pollen viability detected by fluorescein diacetate and quantification of sporad types by acid fuchsin staining. Chromosome number and pairing at meiosis were observed in root tips or in samples of pollen mother cells. A positive relation was found among high seed set, high frequency of viable tetrads, high degree of chromosome pairing, and low frequency of chromosomal aberrations such as inversions and translocations. On the basis of these factors, three types of hybrids could be distinguished. In type one hybrids, chromosomes paired as bivalents, pollen mother cells divided into tetrads, and capsule setting occurred after pollination of pollen acceptors. In type two hybrids, chromosomes remained mainly as univalents that developed into micromeiocytes, pollen mother cell division was disrupted, and seed recovery was low after pollination. Type three hybrids showed chromosomes paired mostly as multivalents, chromosome bridges, pollen mother cell division with massive failure, and little fertility. In Doritaenopsis orchids, high pollen viability and high fertility depends on a high frequency of normal tetrads, and low seed set in cross-pollination is predicted with micronuclei in the end products of meiosis. The occurrence of chromosomal aberrations may suggest a process of genome differentiation that could compromise breeding efforts if not taken into consideration.
Ariningsun P. Cinantya, Fure-Chyi Chen and Yao-Chien Alex Chang
The popularity of the nobile-type dendrobium (Dendrobium nobile hybrids) has been increasing globally. More information regarding the effects of long-distance shipping, from producing countries to destination market countries, on the post-shipping plant performance is needed. In this study, two nobile-type dendrobium cultivars were subjected to simulated dark shipping (SDS) at various temperatures and durations. Changes in net CO2 uptake rate (Pn), chlorophyll fluorescence, and leaf relative water content after plants had been treated with SDS were investigated. Furthermore, shipped plants were vernalized to investigate the effect of dark shipping on the subsequent flowering quality. Dark shipping for 7 days at 15 °C did not affect the post-shipping photosynthetic performance of D. Lan Tarn Beauty. Increasing the shipping duration from 7 to 21 days increased the time required for Pn recovery from 1 to 12 days. Dendrobium Lan Tarn Beauty recovered its Pn within 4 days when shipped for 21 days at 10 °C, and this was prolonged to 11 days when the plants were shipped at 20 °C. Changes in Fv/Fm indicated that there was no marked damage to either cultivars, and the leaf relative water content was little affected by SDS. Dendrobium Lan Tarn Beauty and D. Lucky Girl shipped at 10 °C flowered 5 and 8 days earlier, respectively, compared with unshipped plants. Regardless of the shipping conditions, shipped D. Lucky Girl had a lower flower diameter and higher total flower count than unshipped plants. No differences were found in the number of nodes with flowers or the total flower count between shipped and unshipped D. Lan Tarn Beauty. Our study suggested that dark shipping for up to 21 days is possible for nobile-type dendrobiums. We recommend shipping temperatures of 10 to 15 °C to reduce the detrimental effects caused by long-term dark shipping.
Adelheid R. Kuehnle, Fure-Chyi Chen and Nellie Sugii
Fure-Chyi Chen, Wan-Ling Wu, Chun-Hua Pan, Irwin Yau-Yuan Chu and Yau-Wen Yang
Molecular markers by random amplified polymorphic DNAs were used to evaluate the genetic variation among different Oncidium accessions. It is possible to distinguish different registered Oncidium hybrids, including Gower Ramsey, Sweet Sugar, and Taka using nine random primers. Furthermore, variation was also detected within different cultivars derived from same hybrids. For example, several cultivars of Gower Ramsey could be distinguished based on molecular markers. Based on dendrogram, the investigated cultivars were clustered into several groups. Onc. Gower Ramsey and its selected cultivars were in one group. Onc. Sweet Sugar, Onc. Taka and Onc. Sharry Baby `Sweet Fragrance' were clustered in separate groups.