Inheritance of flower color in Dendranthema grandiflora Tzvelev. (Chrysanthemum morifolium Ramat.) using cultivars and inbreds. I. Plastid pigmentation

Progeny from controlled crosses of 28 garden chrysanthemum (Dendranthema grandiflora Tzvelev.) inbreds in various combinations as males with 3 heterozygous cultivars and 10 inbreds as females were evaluated for plastid pigmentation in a series of field and glasshouse environments. Disomic inheritance of a dominant gene, which acts to inhibit pigmentation, best explained the data. However, 1 of 8 families involving a glasshouse cultivar with colorless plastids ('Puritan') as female and inbreds with yellow plastids as males deviated significantly from the expected 1:1 ratio. This family consistently exhibited an excess of plants with colorless plastids. Although parent clones and cloned progeny from inbred parents were scored the same in field and glasshouse environments, reevaluation in the field of all 8 'Puritan' families, first evaluated in a glasshouse environment, revealed phenotypic misclassification apparently due to environmental effects. An excess of plants with colorless plastids appeared in the glasshouse but evaluation of the same genotypes in the field resulted in an excess of plants having yellow plastids. Submerging ray florets in a hot-water bath revealed yellow plastids masked by vacuolar pigments, thus reducing chances of misclassification. The data suggest that evaluation of highly variable families in a single environment can lead to misclassification of plastid pigmentation. However, even with evaluation in 2 or more environments, certain families may exhibit an excess of plants with colorless plastids.