A. Kanno, M. Hirai, T. Ochiai, H. Simon, G. Theissen
The perianths of Liliaceae plants have two outer whorls of almost identical petaloid organs, called tepals. To explain the morphology of Liliaceae flowers, van Tunen et al. (1993) proposed a modified ABC model, exemplified by tulip. According to this model, class B genes are expressed in whorl 1, as well as in whorls 2 and 3. Thus the organs of both whorls 1 and 2 express class A + B genes and hence get the same petaloid structure. Viridiflora is a well-known cultivar group of tulips, whose organs in whorls 1 and 2 are greenish (partially 'sepaloid') rather than fully petaloid, and whose stamens are slightly degenerated. This phenotype is explained under the modified ABC model by a loss of B-function. In this study, we isolated cDNAs of three putative class B genes - comprising DEF- and GLO-like genes - from the viridiflora tulip cultivar 'Spring Green'. The amino acid sequences derived from these sequences were similar to those from wild type tulip. Northern hybridization showed that the expression of TGDEFA and TGDEFB in viridiflora tulips was weaker than that in wild type plants, whereas the expression patterns of TGGLO from wild type and viridiflora tulips were almost identical. These results suggest that the reduction of the expression level of two DEF-like genes is involved in the development of the viridiflora phenotype.
Kanno, A., Hirai, M., Ochiai, T., Simon, H. and Theissen, G. (2007). REDUCED EXPRESSION OF DEFICIENS-LIKE GENES IN THE SEPALOID TEPALS OF VIRIDIFLORA TULIPS. Acta Hortic. 763, 43-48
DOI: 10.17660/ActaHortic.2007.763.5
Liliaceae, modified ABC model, DEF-like gene, gene expression

Acta Horticulturae