Circadian regulation of the PhCCD1 carotenoid cleavage dioxygenase controls emission of beta-ionone, a fragrance volatile of petunia flowers

• Published in: Plant physiology (Bethesda) Vol. 136; no. 3; pp. 3504 - 3514
• Main Authors: Simkin, A.J, Underwood, B.A, Auldridge, M, Loucas, H.M, Shibuya, K, Schmelz, E, Clark, D.G, Klee, H.J
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Biologists 01.11.2004; American Society of Plant Physiologists
• Subjects: Agronomy. Soil science and plant productions; Amino Acid Sequence; amino acid sequences; beta-ionone; Biochemical Processes and Macromolecular Structures; Biological and medical sciences; carotenoid cleavage dioxygenase; Carotenoids; Cell physiology; Circadian Rhythm; Complementary DNA; Corolla; Dioxygenases - chemistry; Dioxygenases - genetics; Dioxygenases - metabolism; Economic plant physiology; enzyme activity; Enzymes; Escherichia coli - genetics; Escherichia coli - metabolism; Flowering, floral biology, reproduction patterns; Flowers; Flowers - metabolism; Fundamental and applied biological sciences. Psychology; gas emissions; Gene expression regulation; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant - physiology; gene overexpression; Growth and development; Leaves; Light; Lycopersicon esculentum; messenger RNA; Molecular and cellular biology; Molecular Sequence Data; Norisoprenoids - biosynthesis; nucleotide sequences; Organisms, Genetically Modified; oxygenases; Petunia; Petunia - metabolism; Petunia hybrida; Plant biochemistry; Plant Leaves - metabolism; plant proteins; Plants; RNA; Sequence Alignment; Sequence Homology, Amino Acid; Signal transduction; tissue distribution; volatile organic compounds; Volatile compound; Flower; Petunia hybrida; Transcription; Plant leaf; Circadian rhythm; Gene; Dicotyledones; Angiospermae; Lycopersicon esculentum; Spermatophyta; Transgenic plant; Solanaceae; Aroma; Carotenoid
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.104.049718

Carotenoids are thought to be the precursors of terpenoid volatile compounds that contribute to flavor and aroma. One such volatile, beta-ionone, is important to fragrance in many flowers, including petunia (Petunia hybrida). However, little is known about the factors regulating its synthesis in vivo. The petunia genome contains a gene encoding a 9,10(9',10') carotenoid cleavage dioxygenase, PhCCD1. The PhCCD1 is 94% identical to LeCCD1A, an enzyme responsible for formation of beta-ionone in tomato (Lycopersicon esculentum; Simkin AJ, Schwartz SH, Auldridge M, Taylor MG, Klee HJ [2004] Plant J [in press]). Reduction of PhCCD1 transcript levels in transgenic plants led to a 58% to 76% decrease in beta-ionone synthesis in the corollas of selected petunia lines, indicating a significant role for this enzyme in volatile synthesis. Quantitative reverse transcription-PCR analysis revealed that PhCCD1 is highly expressed in corollas and leaves, where it constitutes approximately 0.04% and 0.02% of total RNA, respectively. PhCCD1 is light-inducible and exhibits a circadian rhythm in both leaves and flowers. beta-Ionone emission by flowers occurred principally during daylight hours, paralleling PhCCD1 expression in corollas. The results indicate that PhCCD1 activity and beta-ionone emission are likely regulated at the level of transcript.