HORTSCIENCE 44(1):40–43. 2009. (Deng and Harbaugh, 2006; Wilfret, 1986). The presence of leaf spots is controlled by a single locus with two alleles that are inherited Leaf Blotching in Caladium (Araceae) independently from leaf shape but closely linked with the color of the main vein (Deng Is Under Simple Genetic Control and et al., 2008). Another major foliar trait in caladium is Tightly Linked to Vein Color leaf blotching, the occurrence of numerous irregularly shaped color areas between major Zhanao Deng1 and Brent K. Harbaugh veins on leaf blades. Leaf blotches may University of Florida, IFAS, Environmental Horticulture Department, appear singly or coalesce to large areas of Gulf Coast Research and Education Center, 14625 County Road 672, coloration, up to several inches on mature leaves. This pattern of coloration in combi- Wimauma, FL 33598 nation with bright colors has resulted in Additional index words. Caladium ·hortulanum, leaf characteristics, inheritance, breeding, attractive, highly valued and desired cala- ornamental aroids dium cultivars, including Carolyn Whorton and White Christmas. With large pink or Abstract. Cultivated caladiums (Caladium ·hortulanum Birdsey) are valued as important white blotches, ‘Carolyn Whorton’ and pot and landscape plants because of their bright, colorful leaves. Improving leaf ‘White Christmas’ have been the most pop- characteristics or generating new combinations of these characteristics has been one of ular fancy-leaved pink or white cultivars the most important breeding objectives in caladium. A major leaf characteristic in (Bell et al., 1998; Deng et al., 2005). Interest caladium is leaf blotching, the presence of numerous irregularly shaped color areas in incorporating this coloration pattern into between major veins on leaf blades. This pattern of coloration in combination with bright new cultivars has been strong, but informa- colors has resulted in the popularity of a number of caladium cultivars. In this study, tion on the inheritance of this trait has been controlled crosses were made among three blotched and six nonblotched caladium lacking. cultivars. Their progeny were analyzed to understand the mode of inheritance of leaf Leaf blotches as well as color bands or blotching and its genetic relationship with the color of main leaf veins. Progeny of selfing stripes are common in several aroids and nonblotched or crossing nonblotched cultivars were all nonblotched; selfing blotched have resulted in diverse and intriguing foliar cultivars (Carolyn Whorton, White Christmas, and Florida Blizzard) or crossing coloration patterns in these plants (Henny, ‘Florida Blizzard’ and ‘Carolyn Whorton’ resulted in a 3:1 ratio (blotched:non- 1988). These coloration patterns have been a blotched); and progeny from crosses between blotched and nonblotched cultivars major contributing component to the orna- segregated in a 1:1 ratio (blotched:nonblotched). These results indicate that leaf mental and/or economic value of a number of blotching is controlled by a single nuclear locus with two alleles (B and b). x2 analysis important ornamental aroids (Henny and of the joint segregation between leaf blotching and vein color (V) in five crosses showed Chen, 2003). For example, the occurrence that the blotching allele B is linked to the green vein allele Vg. ‘Carolyn Whorton’, ‘White of white bands, silvery light gray or gray– Christmas’, and ‘Florida Blizzard’ are heterozygous for leaf blotching, and their green blotches, and silvery stripes in various genotype for leaf blotching and vein color (Vr, Vw, and Vg for red, white, and green portions of leaves has resulted in a number of veins, respectively) are Vrb//VgB, Vgb//VgB, and Vwb//VgB, respectively. This information distinct coloration or variegation patterns in will be valuable for planning crosses and breeding populations to develop new blotched several aglaonema species (Aglaonema caladium cultivars. The information gained in this study may be helpful for understanding Schott) (Henny, 1986). Dieffenbachia (Dief- the inheritance of similar traits in other aroids. fenbachia Schott) cultivars often have leaf areas in different shades of green, yellow, cream, and white or combinations of these Cultivated caladiums (Caladium ·hortu- chromosomes (in Darlington and Wylie, colors. Controlled crosses and segregation lanum Birdsey) are members of the aroid 1955) and are propagated asexually through analysis in aglaonema and dieffenbachia family and have been important pot and tuber division in the trade. Central Florida have shown that the inheritance of some of landscape plants (Evans et al., 1992). They growers produce greater than 95% of the these patterns is controlled by nuclear loci are known for their bright and colorful leaves, tubers used in the world for pot plant forcing with multiple alleles (Henny, 1982, 1983, adaptation to tropical and subtropical envi- and landscape planting (Bell et al., 1998; 1986). ronmental conditions, and low landscape Deng et al., 2005). The objectives of this study were to maintenance requirements. Caladiums are be- The ornamental value of caladiums used understand the mode of inheritance of leaf lieved to have resulted from intra- or inter- as pot or landscape plants is determined blotching in caladium, to determine the ge- specific hybridization among several species primarily by leaf characteristics. Improving netic relationship between leaf blotching that originated from the New World’s tropi- leaf characteristics or generating new combi- and vein color, another important foliar trait cal regions, including C. bicolor (Aiton) nations of them has been one of the most for caladium, and to infer the genotype Vent., C. marmoratum Mathieu, C. pictura- important objectives in caladium breeding of important caladium cultivars for leaf tum C. Koch, and C. schomburgkii Schott and cultivar development (Wilfret, 1993). To blotching. (Birdsey, 1951; Hayward, 1950; Wilfret, increase breeding efficiency, efforts have 1993). They are diploids with 2n =2x =30 been made in recent years to gain a better Materials and Methods understanding of the inheritance of foliar traits. These efforts have resulted in a number Plant material. Three blotched (‘Carolyn of findings. For example, it has been found Whorton’, ‘White Christmas’, and ‘Florida Received for publication 30 Sept. 2008. Accepted that the three main leaf shapes in caladium Blizzard’) and six nonblotched (‘Candidum’, for publication 4 Nov. 2008. (fancy or heart-shaped, strap or linear- ‘Fannie Munson’, ‘Frieda Hemple’, ‘Ginger- This research was supported by the Florida Agri- shaped, and lance, an intermediate between land’, ‘Miss Muffet’, and ‘Rosebud’) com- cultural Experiment Station and a grant from fancy and strap) are controlled by a single mercial cultivars were used as parents in 20 USDA/CSREES/TSTAR program. We thank Richard O. Kelly, Joyce Jones, Nancy locus with two codominant alleles (F and f) crosses. ‘Carolyn Whorton’ and ‘White West, and Gail Bowman for their excellent technical (Wilfret, 1986). The three main vein colors Christmas’ have pink and white blotches, support. (red, white, and green) are determined by a respectively. ‘Florida Blizzard’ is a progeny 1To whom reprint requests should be addressed; single locus with three alleles (Vr, Vw, and Vg) of a cross between ‘Aaron’ (nonblotched) and e-mail zdeng@ufl.edu. that are independent from the leaf shape locus ‘White Christmas’ (Harbaugh et al., 2002) 40 HORTSCIENCE VOL. 44(1) FEBRUARY 2009 and has inherited the blotching trait from fumigated with methyl bromide and chloro- ‘White Christmas’. ‘Candidum’, ‘Fannie picrin, covered with white-on-black plastic Munson’, ‘Frieda Hemple’, ‘Gingerland’, mulch, and irrigated with the seepage irriga- ‘Miss Muffet’, and ‘Rosebud’ are all non- tion system (Geraldson et al., 1965). Plants blotched, but their leaves are in different were spaced 25.4 cm apart and grown on the colors (white with green veins, pink, red, beds for three seasons until July 2007. In each white with red spots, lemon green with bur- growing season, 15 g of Osmocote controlled- gundy spots, and pink, respectively). All of release fertilizer (18N–2.6P–10K, 8- to 9- these cultivars have been asexually propa- month; Scotts Co.) was applied to each plant. gated for many years (except ‘Florida Bliz- Progeny of four crosses (or four popula- zard’). Most of them are among the 10 most tions) were also propagated asexually through popular commercial cultivars (Bell et al., tuber division and planted in four replicates 1998; Deng et al., 2005) and have been used in randomized complete blocks to assess frequently as breeding parents for cultivar potential variation in leaf characteristics after development. Their phenotype and inferred asexual propagation. Tuber pieces were planted genotype for leaf blotching and vein color are in new fumigated, mulched ground beds shown in Table 1. between 3 May and 13 June 2007. These Flower induction, pollination, and progeny plants were irrigated and fertilized through a growing. Large, dry tubers (6.4 cm or greater drip system. in diameter) were treated with a GA3 solution Data-taking and analysis. Progeny was (ProGibb T&O; Valent BioSciences, Liberty- scored for leaf blotching (blotched or non- ville, IL; 600 mgÁL–1) overnight at ambient blotched) and main vein color (red, white, or temperature to induce flowers (Harbaugh and green) in June to Nov. 2006 and again in June Wilfret, 1979). Treated tubers were planted in 2007. Each time, multiple fully expanded, plastic