Leaf Blotching in Caladium (Araceae) Is Under Simple Genetic Control and Tightly Linked to Vein Color

Abstract

<jats:p>Cultivated caladiums (<jats:italic>Caladium</jats:italic> ×<jats:italic>hortulanum</jats:italic> Birdsey) are valued as important pot and landscape plants because of their bright, colorful leaves. Improving leaf characteristics or generating new combinations of these characteristics has been one of the most important breeding objectives in caladium. A major leaf characteristic in caladium is leaf blotching, the presence of numerous irregularly shaped color areas between major veins on leaf blades. This pattern of coloration in combination with bright colors has resulted in the popularity of a number of caladium cultivars. In this study, controlled crosses were made among three blotched and six nonblotched caladium cultivars. Their progeny were analyzed to understand the mode of inheritance of leaf blotching and its genetic relationship with the color of main leaf veins. Progeny of selfing nonblotched or crossing nonblotched cultivars were all nonblotched; selfing blotched cultivars (Carolyn Whorton, White Christmas, and Florida Blizzard) or crossing ‘Florida Blizzard’ and ‘Carolyn Whorton’ resulted in a 3:1 ratio (blotched:nonblotched); and progeny from crosses between blotched and nonblotched cultivars segregated in a 1:1 ratio (blotched:nonblotched). These results indicate that leaf blotching is controlled by a single nuclear locus with two alleles (<jats:italic>B</jats:italic> and <jats:italic>b</jats:italic>). χ<jats:sup>2</jats:sup> analysis of the joint segregation between leaf blotching and vein color (<jats:italic>V</jats:italic>) in five crosses showed that the blotching allele <jats:italic>B</jats:italic> is linked to the green vein allele <jats:italic>V</jats:italic><jats:sup>g</jats:sup>. ‘Carolyn Whorton’, ‘White Christmas’, and ‘Florida Blizzard’ are heterozygous for leaf blotching, and their genotype for leaf blotching and vein color (<jats:italic>V</jats:italic><jats:sup>r</jats:sup>, <jats:italic>V</jats:italic><jats:sup>w</jats:sup>, and <jats:italic>V</jats:italic><jats:sup>g</jats:sup> for red, white, and green veins, respectively) are <jats:italic>V</jats:italic><jats:sup>r</jats:sup><jats:italic>b</jats:italic>//<jats:italic>V</jats:italic><jats:sup>g</jats:sup><jats:italic>B</jats:italic>, <jats:italic>V</jats:italic><jats:sup>g</jats:sup><jats:italic>b</jats:italic>//<jats:italic>V</jats:italic><jats:sup>g</jats:sup><jats:italic>B</jats:italic>, and <jats:italic>V</jats:italic><jats:sup>w</jats:sup><jats:italic>b</jats:italic>//<jats:italic>V</jats:italic><jats:sup>g</jats:sup><jats:italic>B</jats:italic>, respectively. This information will be valuable for planning crosses and breeding populations to develop new blotched caladium cultivars. The information gained in this study may be helpful for understanding the inheritance of similar traits in other aroids.</jats:p>

Morphological, cytological and molecular marker analyses of ‘Tapestry’ caladium variants reveal diverse genetic changes and enable association of leaf coloration pattern loci with molecular markers

“…Previously, Harbaugh (2006, 2009) reported that leaf blotching in caladium is controlled by a single nuclear locus (B), with the leaf blotching allele (B) dominant over the non-blotching allele (b) and the leaf main vein color in caladium is controlled by another single nuclear locus (V), with the red allele (V r ) > white allele (V w ) > green allele (V g ). Deng and Harbaugh (2009) also demonstrated that the B and the V locus in caladium are closely linked. The genotype of 'Tapestry' at these two loci is BV g //bV r (Cao and Deng, unpublished), based on phenotyping a large number of progeny from the crosses between 'Tapestry' [blotched (Bb) and red-veined (V g V r )] and other cultivars or breeding lines [non-blotched (bb) and green-veined (V g V g )] and finding that the majority of progeny were blotched and greenveined or non-blotched and red-veined and that the allele B is in coupling phase with V g , and b is in coupling phase with V r .…”

‘Sea Foam Pink’ Caladium

“…'Sea Foam Pink' originated from a cross between 'Carolyn Whorton' and 'Miss Muffet' that was made in Bradenton, FL, in Summer 2005 to investigate the mode of inheritance for their leaf spots (in 'Miss Muffet') and blotches (in 'Carolyn Whorton') (Deng and Harbaugh, 2009;Deng et al, 2008a). Both 'Carolyn Whorton' and 'Miss Muffet' are nonpatented commercial cultivars.…”

“…In caladium, the yellow leaf background color is controlled by a single dominant allele (LEM) and is tightly linked (3 to 4 cM) to the nonspotting allele (s) (Cao et al, 2017). The yellow leaf background color allele is expected to be tightly linked to the nonblotching allele (b) (Deng and Harbaugh, 2009). These genetic linkages may have led to the scarcity of commercial cultivars with yellow leaf background color and leaf spots or blotches.…”

Inheritance of Rugose Leaf in Caladium and Genetic Relationships with Leaf Shape, Main Vein Color, and Leaf Spotting

“…Cultivated caladium is an ornamental aroid produced for container or hanging basket plants or grown in landscapes for their variably shaped, colorful foliage. The ornamental value of caladium plants, to a great extent, depends on their leaf characteristics (Deng and Harbaugh, 2009). Improving leaf characteristics or creating novel combinations has been a main objective in caladium breeding and new cultivar development (Wilfret, 1993).…”

“…The presence or absence of leaf spots is controlled by a single locus S, with the S allele for spotting and the s allele for nonspotting (Deng et al, 2008). Similarly, leaf blotching is determined by a single locus (B) with a dominant allele B for blotching and a recessive allele b for nonblotching (Deng and Harbaugh, 2009). The knowledge gained over the last 25 years on trait inheritance has been valuable for selecting breeding parents and parental combinations and planning breeding populations in caladium.…”