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  • Author or Editor: Richard J. Henny x
  • Journal of the American Society for Horticultural Science x
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Dieffenbachia Schott is an important ornamental foliage plant genus. A total of 30 species has been recognized, but most cultivars come from or are related to a single species, D. maculata (Lodd.) G. Don. At least 11 of the cultivars are sports or somaclonal variants. As a result, the potential lack of genetic diversity in cultivated Dieffenbachia has become a concern. However, no research has been conducted to determine the genetic relatedness of the cultivars. This study analyzed the genetic similarity of 42 Dieffenbachia cultivars using amplified fragment length polymorphism (AFLP) markers. Six primer sets, selected from an initial screening of 48, generated a total of 453 scorable AFLP fragments of which 323 (71%) are polymorphic. All cultivars were clearly differentiated by their AFLP fingerprints. A dendrogram was constructed using the unweighted pair-group method of arithmetic averages, and principal coordinated analysis was carried out to show multiple dimensions of the distribution of the cultivars. The 42 cultivars were divided into three clusters; clusters I and II comprise 18 and 23 cultivars, respectively. Jaccard's similarity coefficients for cultivars in the clusters I and II varied from 0.44 to 0.95 and 0.41 to 0.87, respectively. These results indicate that broadening the genetic variability in the Dieffenbachia gene pool is needed, but the genetic similarity of many cultivars is not as close as previously thought. Additionally, Jaccard's similarity coefficients between most sports or somaclonal variants and their parents were 0.73 or lower, suggesting that accumulation of somatic mutations through tissue culture may play a role in the increased variation between some sports or variants and their parents.

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Philodendrons (Philodendron Schott) are among the most popular tropical ornamental foliage plants used for interior decoration. However, limited information is available on the genetic relationships among popular Philodendron species and cultivars. This study analyzed genetic similarity of 43 cultivars across 15 species using amplified fragment length polymorphism (AFLP) markers with near infrared fluorescence labeled primers. Forty-eight EcoR I + 2/Mse I + 3 primer set combinations were screened, from which six primer sets were selected and used in this investigation. Each selected primer set generated 96 to 130 scorable fragments. A total of 664 AFLP fragments were detected, of which 424 (64%) were polymorphic. All cultivars were clearly differentiated by their AFLP fingerprints, and the relationships were analyzed using the unweighted pair-group method of arithmetic average cluster analysis (UPGMA) and principal coordinated analysis (PCA). The 43 cultivars were divided into five clusters. Cluster I comprises eight cultivars with arborescent growth style. Cluster II has only one cultivar, `Goeldii'. There are 16 cultivars in cluster III, and most of them are self-heading interspecific hybrids originated from R.H. McColley's breeding program in Apopka, Fla. Cluster IV contains 13 cultivars that exhibit semi-vining growth style. Cluster V has five cultivars that are true vining in morphology, and they have lowest genetic similarity with philodendrons in other clusters. Cultivated philodendrons are generally genetically diverse except the self-heading hybrids in cluster III that were mainly developed using self-heading and semi-vining species as parents. Seven hybrid cultivars have Jaccard's similarity coefficients of 0.88 or higher, suggesting that future hybrid development needs to select parents with diverse genetic backgrounds.

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