Increasing ω-3 Desaturase Expression in Tomato Results in Altered Aroma Profile and Enhanced Resistance to Cold Stress

• Published in: Plant physiology (Bethesda) 2010-06, Vol.153 (2), p.655-665
• Main Authors: Domínguez, Teresa, Hernández, M. Luisa, Pennycooke, Joyce C, Jiménez, Pedro, Martínez-Rivas, José Manuel, Sanz, Carlos, Stockinger, Eric J, Sánchez-Serrano, José J, Sanmartín, Maite
• Format: Article
• Language: English
• Subjects: Acclimatization; Aldehydes; alpha-Linolenic Acid - metabolism; BIOCHEMICAL PROCESSES AND MACROMOLECULAR STRUCTURES; Biological and medical sciences; Brassica napus - enzymology; Chloroplasts - enzymology; Cold Temperature; Cooling; Endoplasmic Reticulum - enzymology; Enzymes; Fatty Acid Desaturases - genetics; Fatty Acid Desaturases - metabolism; Fatty acids; Fundamental and applied biological sciences. Psychology; Hexobarbital - metabolism; Leaves; Linoleic Acid - metabolism; Lipids; Low temperature; Lycopersicon esculentum - enzymology; Lycopersicon esculentum - genetics; Odorants; Oxylipins - metabolism; Plant physiology and development; Plant Proteins - genetics; Plant Proteins - metabolism; Plants; Plants, Genetically Modified - enzymology; Plants, Genetically Modified - genetics; RNA, Plant - genetics; Solanum tuberosum - enzymology; Transformation, Genetic; Transgenic plants
• ISSN: 0032-0889; 1532-2548; 1532-2548
• DOI: 10.1104/pp.110.154815

One of the drawbacks in improving the aroma properties of tomato (Solanum lycopersicum) fruit is the complexity of this organoleptic trait, with a great variety of volatiles contributing to determine specific quality features. It is well established that the oxylipins hexanal and (Z)-hex-3-enal, synthesized through the lipoxygenase pathway, are among the most important aroma compounds and impart in a correct proportion some of the unique fresh notes in tomato. Here, we confirm that all enzymes responsible for the synthesis of these C6 compounds are present and active in tomato fruit. Moreover, due to the low odor threshold of (Z)-hex-3-enal, small changes in the concentration of this compound could modify the properties of the tomato fruit aroma. To address this possibility, we have overexpressed the ω-3 fatty acid desaturases FAD3 and FAD7 that catalyze the conversion of linoleic acid (18:2) to linolenic acid (18:3), the precursor of hexenals and its derived alcohols. Transgenic OE-FAD tomato plants exhibit altered fatty acid composition, with an increase in the 18:3/18:2 ratio in leaves and fruits. These changes provoke a clear variation in the C6 content that results in a significant alteration of the (Z)-hex-3-enal/hexanal ratio that is particularly important in ripe OE-FAD3FAD7 fruits. In addition to this effect on tomato volatile profile, OE-FAD tomato plants are more tolerant to chilling. However, the different behaviors of OE-FAD plants underscore the existence of separate fatty acid fluxes to ensure plant survival under adverse conditions.