Silencing Nicotiana attenuata LHY and ZTL alters circadian rhythms in flowers

• Published in: The New phytologist Vol. 209; no. 3; pp. 1058 - 1066
• Main Authors: Yon, Felipe, Joo, Youngsung, Cortés Llorca, Lucas, Rothe, Eva, Baldwin, Ian T, Kim, Sang‐Gyu
• Format: Journal Article
• Language: English
• Published: England Academic Press 01.02.2016; New Phytologist Trust; Wiley Subscription Services, Inc
• Subjects: acetone; Arabidopsis thaliana; circadian clock; circadian rhythm; Circadian Rhythm - genetics; emissions; floral rhythms; flowers; Flowers - genetics; Flowers - physiology; Gene Expression Regulation, Plant; Gene Silencing; genes; genetically modified organisms; hypocotyls; NaLHY; NaZTL; Nicotiana - genetics; Nicotiana - physiology; Nicotiana attenuata; Odorants; odors; pedicel; Plant Proteins - genetics; Plant Proteins - metabolism; pollinators; RNA, Messenger - genetics; RNA, Messenger - metabolism; Seedlings - metabolism; tobacco; Volatilization; wild flowers; Nicotiana attenuata; floral rhythms; NaLHY; circadian clock; NaZTL
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/nph.13681

The rhythmic opening/closing and volatile emissions of flowers are known to attract pollinators at specific times. That these rhythms are maintained under constant light or dark conditions suggests a circadian clock involvement. Although a forward and reverse genetic approach has led to the identification of core circadian clock components in Arabidopsis thaliana, the involvement of these clock components in floral rhythms has remained untested, probably because of the weak diurnal rhythms in A. thaliana flowers. Here, we addressed the role of these core clock components in the flowers of the wild tobacco Nicotiana attenuata, whose flowers open at night, emit benzyl acetone (BA) scents and move vertically through a 140° arc. We first measured N. attenuata floral rhythms under constant light conditions. The results suggest that the circadian clock controls flower opening, BA emission and pedicel movement, but not flower closing. We generated transgenic N. attenuata lines silenced in the homologous genes of Arabidopsis LATE ELONGATED HYPOCOTYL (LHY) and ZEITLUPE (ZTL), which are known to be core clock components. Silencing NaLHY and NaZTL strongly altered floral rhythms in different ways, indicating that conserved clock components in N. attenuata coordinate these floral rhythms.