Flower-specificKNOXphenotype in the orchidDactylorhiza fuchsii

• Published in: Journal of experimental botany Vol. 63; no. 13; pp. 4811 - 4819
• Main Authors: Box, Mathew S., Dodsworth, Steven, Rudall, Paula J., Bateman, Richard M., Glover, Beverley J.
• Format: Journal Article
• Language: English
• Published: OXFORD UNIVERSITY PRESS 01.01.2012
• Subjects: Carpels; Corolla; Developmental biology; Flowers; Genes; Homeobox genes; Ovaries; Phenotypes; Plants; RESEARCH PAPER; Reverse transcriptase polymerase chain reaction
• ISSN: 0022-0957; 1460-2431

TheKNOTTED1-like homeobox (KNOX) genes are best known for maintaining a pluripotent stem-cell population in the shoot apical meristem that underlies indeterminate vegetative growth, allowing plants to adapt their development to suit the prevailing environmental conditions. More recently, the function of theKNOXgene family has been expanded to include additional roles in lateral organ development such as complex leaf morphogenesis, which has come to dominate theKNOXliterature. Despite several reports implicatingKNOXgenes in the development of carpels and floral elaborations such as petal spurs, few authors have investigated the role ofKNOXgenes in flower development. Evidence is presented here of a flower-specificKNOXfunction in the development of the elaborate flowers of the orchidDactylorhiza fuchsii, which have a three-lobed labellum petal with a prominent spur. Using degenerate PCR, four Class IKNOXgenes (DfKN1–4) have been isolated, one from each of the four major Class I KNOX subclades and by reverse transcription PCR (RT-PCR), it is demonstrated thatDfKNOXtranscripts are detectable in developing floral organs such as the spur-bearing labellum and inferior ovary. Although constitutive expression of theDfKN2transcript in tobacco produces a wide range of floral abnormalities, including serrated petal margins, extra petal tissue, and fused organs, none of the vegetative phenotypes typical of constitutiveKNOXexpression were produced. These data are highly suggestive of a role forKNOXexpression in floral development that may be especially important in taxa with elaborate flowers.