Conical petal epidermal cells, regulated by the MYB transcription factor MIXTA, have an ancient origin within the angiosperms. (21st May 2022)

• Record Type: Journal Article
• Authors: Reed, Alison; Rudall, Paula J; Brockington, Samuel F; Glover, Beverley J
• Editors: Bartlett, Madelaine
• Is Part Of: Journal of experimental botany. Volume 73:Number 16(2022)
• Page Start: 5490
• Page End: 5502
• Publication Date: 2022-05-21
• Subjects: ANA grade -- Cabomba caroliniana -- conical cell -- MIXTA -- Nymphaeales -- papillae -- petal -- tepal; Botany -- Periodicals; Botany, Experimental -- Periodicals; Plant physiology -- Periodicals; 580
• DOI: 10.1093/jxb/erac223
• Languages: English
• ISSNs: 0022-0957

Abstract

Abstract : Some of the earliest diverging flowers have pollinator-attracting conical cells, indicating that the genetic pathway controlling their development is also ancient. Abstract: Conical epidermal cells occur on the tepals (perianth organs, typically petals and/or sepals) of the majority of animal-pollinated angiosperms, where they play both visual and tactile roles in pollinator attraction, providing grip to foraging insects, and enhancing colour, temperature, and hydrophobicity. To explore the evolutionary history of conical epidermal cells in angiosperms, we surveyed the tepal epidermis in representative species of the ANA-grade families, the early-diverging successive sister lineages to all other extant angiosperms, and analysed the function of a candidate regulator of cell outgrowth from Cabomba caroliniana (Nymphaeales). We identified conical cells in at least two genera from different families ( Austrobaileya and Cabomba ). A single SBG9 MYB gene was isolated from C. caroliniana and found to induce strong differentiation of cellular outgrowth, including conical cells, when ectopically expressed in Nicotiana tabacum. Ontogenetic analysis and quantitative reverse transcription–PCR established that CcSBG9A1 is spatially and temporally expressed in a profile which correlates with a role in conical cell development. We conclude that conical or subconical cells on perianth organs are ancient within the angiosperms and most probably develop using a common genetic programme initiated by a SBG9 MYB transcription factor.