Ranamalie Amarasinghe1, Jacqueline Poldy1, Yuki Matsuba1, Russell A Barrow1, Jan M Hemmi1, Eran Pichersky1, Rod Peakall2. 1. Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia, Research School of Chemistry, The Australian National University, Canberra, ACT 0200, Australia, Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA and School of Animal Biology & Oceans Institute, University of Western Australia, Perth, WA 6009, Australia. 2. Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia, Research School of Chemistry, The Australian National University, Canberra, ACT 0200, Australia, Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA and School of Animal Biology & Oceans Institute, University of Western Australia, Perth, WA 6009, Australia rod.peakall@anu.edu.au.
Abstract
BACKGROUND AND AIMS: Australian sexually deceptive Chiloglottis orchids attract their specific male wasp pollinators by means of 2,5-dialkylcyclohexane-1,3-diones or 'chiloglottones', representing a newly discovered class of volatiles with unique structures. This study investigated the hypothesis that UV-B light at low intensities is directly required for chiloglottone biosynthesis in Chiloglottis trapeziformis. METHODS: Chiloglottone production occurs only in specific tissue (the callus) of the labellum. Cut buds and flowers, and whole plants with buds and flowers, sourced from the field, were kept in a growth chamber and interactions between growth stage of the flowers and duration and intensity of UV-B exposure on chiloglottone production were studied. The effects of the protein synthesis inhibitor cycloheximide were also examined. KEY RESULTS: Chiloglottone was not present in buds, but was detected in buds that were manually opened and then exposed to sunlight, or artificial UV-B light for ≥5 min. Spectrophotometry revealed that the sepals and petals blocked UV-B light from reaching the labellum inside the bud. Rates of chiloglottone production increased with developmental stage, increasing exposure time and increasing UV-B irradiance intensity. Cycloheximide did not inhibit the initial production of chiloglottone within 5 min of UV-B exposure. However, inhibition of chiloglottone production by cycloheximide occurred over 2 h of UV-B exposure, indicating a requirement for de novo protein synthesis to sustain chiloglottone production under UV-B. CONCLUSIONS: The sepals and petals of Chiloglottis orchids strongly block UV-B wavelengths of light, preventing chiloglottone production inside the bud. While initiation of chiloglottone biosynthesis requires only UV-B light, sustained chiloglottone biosynthesis requires both UV-B and de novo protein biosynthesis. The internal amounts of chiloglottone in a flower reflect the interplay between developmental stage, duration and intensity of UV-B exposure, de novo protein synthesis, and feedback loops linked to the starting amount of chiloglottone. It is concluded that UV-B light contributes directly to chiloglottone biosynthesis. These findings suggest an entirely new and unexpected biochemical reaction that might also occur in taxa other than these orchids.
BACKGROUND AND AIMS: Australian sexually deceptive Chiloglottis orchids attract their specific male wasp pollinators by means of 2,5-dialkylcyclohexane-1,3-diones or 'chiloglottones', representing a newly discovered class of volatiles with unique structures. This study investigated the hypothesis that UV-B light at low intensities is directly required for chiloglottone biosynthesis in Chiloglottis trapeziformis. METHODS:Chiloglottone production occurs only in specific tissue (the callus) of the labellum. Cut buds and flowers, and whole plants with buds and flowers, sourced from the field, were kept in a growth chamber and interactions between growth stage of the flowers and duration and intensity of UV-B exposure on chiloglottone production were studied. The effects of the protein synthesis inhibitor cycloheximide were also examined. KEY RESULTS:Chiloglottone was not present in buds, but was detected in buds that were manually opened and then exposed to sunlight, or artificial UV-B light for ≥5 min. Spectrophotometry revealed that the sepals and petals blocked UV-B light from reaching the labellum inside the bud. Rates of chiloglottone production increased with developmental stage, increasing exposure time and increasing UV-B irradiance intensity. Cycloheximide did not inhibit the initial production of chiloglottone within 5 min of UV-B exposure. However, inhibition of chiloglottone production by cycloheximide occurred over 2 h of UV-B exposure, indicating a requirement for de novo protein synthesis to sustain chiloglottone production under UV-B. CONCLUSIONS: The sepals and petals of Chiloglottis orchids strongly block UV-B wavelengths of light, preventing chiloglottone production inside the bud. While initiation of chiloglottone biosynthesis requires only UV-B light, sustained chiloglottone biosynthesis requires both UV-B and de novo protein biosynthesis. The internal amounts of chiloglottone in a flower reflect the interplay between developmental stage, duration and intensity of UV-B exposure, de novo protein synthesis, and feedback loops linked to the starting amount of chiloglottone. It is concluded that UV-B light contributes directly to chiloglottone biosynthesis. These findings suggest an entirely new and unexpected biochemical reaction that might also occur in taxa other than these orchids.
Authors: Rod Peakall; Daniel Ebert; Jacqueline Poldy; Russell A Barrow; Wittko Francke; Colin C Bower; Florian P Schiestl Journal: New Phytol Date: 2010-06-07 Impact factor: 10.151
Authors: Grégory Guirimand; Andrew John Simkin; Nicolas Papon; Sébastien Besseau; Vincent Burlat; Benoit St-Pierre; Nathalie Giglioli-Guivarc'h; Marc Clastre; Vincent Courdavault Journal: J Plant Physiol Date: 2012-03-27 Impact factor: 3.549
Authors: Björn Bohman; Lynne Jeffares; Gavin Flematti; Ryan D Phillips; Kingsley W Dixon; Rod Peakall; Russell A Barrow Journal: Org Lett Date: 2012-05-03 Impact factor: 6.005
Authors: Ryan D Phillips; Daniela Scaccabarozzi; Bryony A Retter; Christine Hayes; Graham R Brown; Kingsley W Dixon; Rod Peakall Journal: Ann Bot Date: 2013-12-22 Impact factor: 4.357
Authors: Hoo Sun Chung; Abraham J K Koo; Xiaoli Gao; Sastry Jayanty; Bryan Thines; A Daniel Jones; Gregg A Howe Journal: Plant Physiol Date: 2008-01-25 Impact factor: 8.340
Authors: Björn Bohman; Ryan D Phillips; Myles H M Menz; Ben W Berntsson; Gavin R Flematti; Russell A Barrow; Kingsley W Dixon; Rod Peakall Journal: New Phytol Date: 2014-04-03 Impact factor: 10.151
Authors: Lucas Vanhaelewyn; András Viczián; Els Prinsen; Péter Bernula; Alejandro Miguel Serrano; Maria Veronica Arana; Carlos L Ballaré; Ferenc Nagy; Dominique Van Der Straeten; Filip Vandenbussche Journal: Plant Cell Date: 2019-07-09 Impact factor: 11.277
Authors: Darren C J Wong; Ranamalie Amarasinghe; Claudia Rodriguez-Delgado; Rodney Eyles; Eran Pichersky; Rod Peakall Journal: Front Plant Sci Date: 2017-07-19 Impact factor: 5.753