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Zhanao Deng, Fahrettin Goktepe, and Brent K. Harbaugh

The ornamental value of caladium (Caladium ×hortulanum Birdsey) depends to a large extent on its foliar characteristics. Efficient genetic improvement of caladium foliar characteristics requires a good understanding of the inheritance of these traits, including leaf shape, color, and spots. This study was conducted to determine the inheritance of leaf spots in caladium and to understand their relationships with leaf shape and main vein color. Eighteen controlled crosses were made among eight commercial cultivars expressing red or no leaf spots, and progeny of these crosses were observed for segregation of leaf spots as well as leaf shape and vein color. A single locus with two alleles is shown to be responsible for the presence or absence of leaf spots in caladium, with the presence allele (S) dominant over the absence allele (s). The major spotted commercial cultivar Gingerland is heterozygous for this trait. Leaf spots are inherited independently from leaf shape, but they are closely linked with the color of the main leaf veins. The recombination frequencies between the leaf spot locus and the main vein color locus ranged from 0.0% to 8.9% with the crosses or the parental cultivars used, with an average of 4.4%. Leaf spots and vein colors represent the first linkage group of ornamental traits in caladium and possibly in other ornamental aroids. The knowledge gained in this study will be valuable when it comes to determine what crosses to make for development of new cultivars. It may be also useful to those interested in determining the inheritance of similar traits in other ornamental plants, including other ornamental aroids such as dieffenbachia (Dieffenbachia Schott).

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Zhanao Deng, Brent K. Harbaugh, and Natalia A. Peres

Caladiums (Caladium ×hortulanum Birdsey, Araceae Juss.) are ornamental aroids grown for their bright, colorful leaves. Their short forcing period, shade tolerance, and low maintenance requirements in the landscape make caladiums popular among pot-plant producers, homeowners, and landscapers (Evans et al., 1992; Harbaugh and Tjia, 1985). The majority of caladiums commercially produced in the world belong to the fancy leaf type, and the most popular color has been white (white center with green veins or white center with white veins). In surveys of Florida caladium growers, who supply more than 95% of the caladium tubers

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Zhanao Deng, Brent K. Harbaugh, and Natalia A. Peres

Caladiums (Caladium ×hortulanum Birdsey, Araceae Juss.) are ornamental aroids valued for their bright colorful leaves. They are commonly used as container and landscape plants. Pink cultivars have been very popular and the most popular pink cultivars have been Carolyn Whorton, Fannie Munson, and White Queen (Bell et al., 1998; Deng et al., 2008). They ranked No.1, No.3, and No. 4 in acreage (or popularity) according to a 2003 survey of the caladium cultivars commercially grown in Florida, where more than 95% of the caladium tubers used in the world are produced (Bell et

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Zhanao Deng, Brent K. Harbaugh, and Natalia A. Peres

Caladiums (Caladium ×hortulanum Birdsey, Araceae Juss.) are commonly grown in pots, hanging baskets, and other container types, or planted in the landscape as accent and border plants (Evans et al., 1992). They are valued for a wide array of leaf colors, coloration patterns, and shapes. The majority of commercially available caladium plants are forced from tubers. Florida growers supply the great majority of the caladium tubers used in the United States and in the world. Frequent introduction of new cultivars is important to both the Florida tuber-producing industry and landscape and greenhouse/nursery industries. New

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Zhanao Deng, Brent K. Harbaugh, and Natalia A. Peres

Caladiums [Caladium ×hortulanum Birdsey, Araceae Juss.] are ornamental aroids widely used as pot and landscape plants for their colorful foliage and ease in growing (Evans et al., 1992; Harbaugh and Tjia, 1985). Tens of millions of caladium tubers are used annually by the worldwide ornamental industries with 70% to 80% forced in containers and 20% to 30% directly planted in the landscape. More than 95% of the tubers used worldwide are produced in central Florida.

Based on leaf shape (fancy or heart-shaped and lance) and predominant leaf color (white, red, pink, and

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Zhanao Deng, Brent K. Harbaugh, and Natalia A. Peres

Caladiums (Caladium ×hortulanum Birdsey, Araceae Juss.) are valued for their colorful and variably shaped leaves (Harbaugh and Tjia, 1985; Wilfret, 1993). Commercial caladium cultivars generally are grouped into the fancy- or lance-leaved type (Wilfret, 1986). Fancy-leaved caladiums produce large round-ovate to triangular leaves with three main veins, two large basal lobes partially to fully joined, and a petiole attached to the back of the leaf blade. Lance-leaved caladiums produce leaves that are sagittate to cordate-lanceolate and have basal lobes obvious to barely obvious and petioles attached to the base of

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Richard O. Kelly, Zhanao Deng, and Brent K. Harbaugh

Central Florida has a climate similar to many locations in the southeastern United States and parts of Asia, Europe, and Australia. Thus, Florida is an important testing ground for new bedding plant cultivars not only in the United States, but around the world. The authors evaluated 125 petunia (Petunia ×hybrida) cultivars in replicated class tests at Bradenton, Fla. (lat. 27º4′N, long. 82º5′W) in 2000–04 and at Balm, Fla. (lat. 27º8′N, long. 82º2′W) in 2005–06. In this report they establish petunia classes and cultivar standards for each class, and provide objective plant measurements of vegetative and floral characteristics, and subjective performance ratings. Petunia cultivars were grouped into 73 classes based on the distinguishing characteristics for petunia, which are plant type and height, and flower type, color, and color pattern. Comparisons were made within each class to determine performance and to select a cultivar as the standard for the class—a plant with the highest overall performance rating that can represent the class in future trials against new cultivars. During the initial trials, larger numbers of cultivars were evaluated and eliminated from future comparisons when each class standard was selected. Many flower colors and color combinations, as well as plant types and other distinctive characteristics have been developed for bedding plants. By creating class standards for each distinctive characteristic, better choices over a wider range of classes are available to growers and landscapers in this climate. Cultivars with an outstanding overall performance rating (combined foliage, flower, arthropod feeding symptom, and disease symptom ratings ≥5.5 points on a 1 to 7-point scale) for class standard selections were (floribunda, single mix class) ‘Madness Waterfall Mix’ and [single purple (dark), red-violet class] ‘Madness Magenta’; [grandiflora, single blue (dark) class] ‘Eagle Blue’, (single orange shades/tints class) ‘Ultra Salmon’, and [single purple (dark), red-violet class] ‘Storm Violet’; and [spreading, normal, orange (dark) shades/tints class] ‘Ramblin’ Salmon Capri’, [orange (light) shades/tints class] ‘Ramblin’ Peach Glo’, [pink (dark) class] ‘Wave Pink’, [purple (dark), blue-violet class] ‘Avalanche Lavender’, [purple (light) blue-violet class] ‘Ramblin’ Lavender’, (red class) ‘Avalanche Red Improved’, (rose class) ‘Avalanche Rose Improved’, (white class) ‘Plush White’, and [spreading, tall; blue (dark) class] ‘Wave Blue’. These cultivars would likely perform well in the southern United States or areas of the world with similar heat and cold hardiness zones.

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Zhanao Deng, Fahrettin Goktepe, Brent K. Harbaugh, and Jinguo Hu

Caladium (Caladium ×hortulanum Birdsey) is an important aroid widely used in the ornamental plant industry. Concerns have been raised about possible loss of genetic diversity due to a drastic decline in the number of cultivars in the last century. This study assessed genetic diversity and relationships among caladium cultivars and species accessions. Forty-five major cultivars and 14 species accessions were analyzed based on 297 DNA fragments produced by the target-region amplification polymorphism marker system. A low level of diversity (44.4% polymorphism) was exhibited in cultivars, while a high level of diversity (96.8% polymorphism) was present among seven accessions of Caladium bicolor (Aiton) Vent., Caladium marmoratum Mathieu, Caladium picturatum C. Koch, and Caladium schomburgkii Schott. A small percentage (7.6%) of DNA fragments was present in cultivars but absent in the seven species accessions, while a high percentage (32.2%) of DNA fragments was present in the seven species accessions but absent in cultivars. Cultivars shared a higher level of similarity at the molecular level with an average Jaccard coefficient at 0.802, formed a large group in cluster analysis, and concentrated in the scatter plot from a principal-coordinate analysis. Two accessions of C. bicolor and C. schomburgkii were very similar to cultivars with Jaccard similarity coefficients from 0.531 to 0.771, while the rest of the species accessions had small similarity coefficients with cultivars (0.060 to 0.386). Caladium steudnirifolium Engler and Caladium lindenii (André) Madison were very dissimilar to C. bicolor, C. marmoratum, C. picturatum, and C. schomburgkii, with Jaccard similarity coefficients from 0.149 to 0.237 (C. steudnirifolium) and from 0.060 to 0.118 (C. lindenii). There is a limited amount of molecular diversity in caladium cultivars, but the great repertoire of unique genes in species accessions could be used to enhance the diversity in future cultivars and reduce potential genetic vulnerability.

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Richard O. Kelly, Zhanao Deng, and Brent K. Harbaugh

Florida is one of the top wholesale producers of bedding plants, and in 2003 was ranked fourth in the United States in annual bedding plant production and fifth in potted pansy (Viola ×wittrockiana) and viola (V. cornuta) production. Evaluation of viola cultivars is vital for continued growth of the industry. We evaluated 66 viola cultivars in replicated class tests at the University of Florida's Gulf Coast Research and Education Center at Bradenton from 2000-04 and determined the best-of-class for use in future trials to compare against new entries in the same class. In this report, we provide objective plant measurements of vegetative and floral characteristics as well as subjective performance ratings. Viola cultivars were grouped into classes based on growth habit (standard vs. creeping), flower color, and flower color pattern, and the best cultivar in each class was determined. Cultivars with an outstanding overall performance rating (combined foliage, flower, arthropod feeding symptom, and disease symptom ratings ≥5.5 out of a 7 high scale) for best-of-class selections were: (standard black class) `Sorbet Black Delight'; (standard cream class) `Velour Cream Splash'; (standard mix class) `Babyface Mixture'; (standard orange with purple, red-violet cap class) `Penny Orange Jump-Up'; [standard purple (dark), blue-violet with dark eye and light cap class] `Angel Violet Blotch'; (standard white class) `Penny White'; [standard white face with purple (dark), red-violet cap class] `Skippy White With Violet Wing'; (standard yellow class) `Jewel Lemon Yellow'; (standard yellow with blotch class) `Babyface Yellow'; [standard yellow/white face with purple (dark), blue-violet cap class] `Penny Classic Jump-Up'. Solitary cultivar entries (without comparison) with outstanding performance were: `Angel Frosted Yellow Blotch', `Angel Violet Duet', `Babyface White', `Eryln Purple Yellow', `Four Seasons Yellow With Pink Wing', `Gem Antique Apricot', `Gem Antique Pink', `Gem Antique Lavender', `Hobbit Bilbo Baggins', `Jewel Deep Blue', `Penny Azure Twilight', `Penny Beaconsfield', `Penny Cream', `Penny Orange', `Penny Orchid Frost', `Penny Purple', `Penny Yellow Jump-Up', `Princess Lavender and Yellow', `Princess Purple and Gold', `Rebel Yellow', `Sorbet Coconut Swirl', `Sorbet Icy Blue', `Sorbet Lemon Swirl', `Sparkler Purple Orange Face', and `Sparkler Purple Wing'. These cultivars would likely perform well in the southern U.S. or areas of the world with similar heat and cold hardiness zones.

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Weining Wang, Yanhong He, Zhe Cao, and Zhanao Deng

Garden impatiens (Impatiens walleriana), a very important floricultural crop in the United States, has been devastated by impatiens downy mildew (IDM) in recent years. This study was conducted to determine if induced tetraploidy could improve impatiens resistance to downy mildew. Tetraploids were induced by colchicine and confirmed by chromosome counting. Compared with diploids, induced tetraploids showed significant morphological changes, including larger and thicker leaves with larger and fewer stomata; thicker and fewer stems; larger and fewer flowers; and larger pollen grains with higher stainability. In detached leaf and in vivo inoculation assays, tetraploids exhibited improved downy mildew resistance, with lower disease severity, disease incidences, and sporangia densities. Plasmopara obducens, the causal agent of IDM, underwent a similar development process in the leaf tissue of diploids and tetraploids. These results suggest that induced tetraploidy can result in significant changes in impatiens leaf and plant morphology and can increase impatiens resistance to downy mildew to a certain extent.