Enzymes of jasmonate biosynthesis occur in tomato [Lycopersicon esculentum] sieve elements

• Published in: Plant and cell physiology 2003-06, Vol.44 (6), p.643-648
• Main Authors: Hause, B. (Institute for Plant Biochemistry, Halle (Germany)), Hause, G, Kutter, C, Miersch, O, Wasternack, C
• Format: Article
• Language: English
• Subjects: 12-oxo-phytodienoic acid; 13-HPOT; 13-hydroperoxy-octadecatrienoic acid; 13-lipoxygenase; 13-LOX; allene oxide cyclase; allene oxide synthase; AOC; AOS; BIOSYNTHESIS; companion cells; Cyclopentanes - metabolism; ENZYMES; Fatty Acids, Unsaturated - biosynthesis; flowers; Flowers - enzymology; Flowers - ultrastructure; Gene Expression Regulation, Enzymologic - genetics; Gene Expression Regulation, Plant - genetics; histology; Immunohistochemistry; Intramolecular Oxidoreductases - genetics; Intramolecular Oxidoreductases - metabolism; JA methyl ester; JAME; JASMONATES; jasmonic acid; Keywords: Enzymes in JA biosynthesis — Immunocytochemistry — Sieve elements — Tomato; lipoxygenase; Lipoxygenase - metabolism; LYCOPERSICON ESCULENTUM; Lycopersicon esculentum - enzymology; Lycopersicon esculentum - ultrastructure; messenger RNA; Microscopy, Electron; OPDA; oxidoreductases; Oxylipins; PHLOEM; plant anatomy; plant proteins; Plant Stems - enzymology; Plant Stems - ultrastructure; Plastids - enzymology; Plastids - ultrastructure; protein synthesis; RNA, Messenger - metabolism; sieve elements; Signal Transduction - physiology; Solanum lycopersicum var. lycopersicum; tomatoes; transgenic plants; vegetable crops; Wound Healing - physiology; α-LeA; α-linolenic acid
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/pcp/pcg072

The allene oxide cyclase (AOC) is a plastid-located enzyme in the hiosynthesis of the signaling compound jasmonic acid (JA). In tomato, AOC occurs specifically in ovules and vascular bundles [Hause et al. (2000) Plant J. 24; 113]. Immunocytological analysis of longitudinal sections of petioles and flower stalks revealed the occurrence of AOC in companion cells (CC) and sieve elements (SE). Electron microscopic analysis led to the conclusion that the AOC-containing structures of SE are plastids. AOC was not detected in SE of 35S::AOCantisense plants. The enzymes preceding AOC in JA biosynthesis, the allene oxide synthase (AOS) and the lipoxygenase, were also detected in SE. In situ hybridization showed that the SE are free of AOC-mRNA suggesting AOC protein traffic from CC to SE via plasmodesmata. A control by in situ hybridization of AOS mRNA coding for a protein with a size above the exclusion limit of plasmodesmata indicated mRNA in CC and SE. The data suggest that SE carry the capacity to form 12-oxo-phytodienoic acid, the unique precursor of JA. Together with preferential generation of JA in vascular bundles [Stenzel et al. (2003) Plant J. 33: 577], the data support a role of JA in systemic wound signaling.