Increasing omega-3 desaturase expression in tomato results in altered aroma profile and enhanced resistance to cold stress.
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 omega-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.
Domínguez
Teresa
T
Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049 Madrid, Spain.
Hernández
M Luisa
ML
Pennycooke
Joyce C
JC
Jiménez
Pedro
P
Martínez-Rivas
José Manuel
JM
Sanz
Carlos
C
Stockinger
Eric J
EJ
Sánchez-Serrano
José J
JJ
Sanmartín
Maite
M
D029688:Brassica napus / Q000201:enzymology; D002736:Chloroplasts / Q000201:enzymology; D003080:Cold Temperature; D004721:Endoplasmic Reticulum / Q000201:enzymology; D044943:Fatty Acid Desaturases / Q000235:genetics / Q000378:metabolism*; D006591:Hexobarbital / Q000378:metabolism*; D019787:Linoleic Acid / Q000378:metabolism; D018551:Solanum lycopersicum / Q000201:enzymology* / Q000235:genetics; D009812:Odorants; D054883:Oxylipins / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D011198:Solanum tuberosum / Q000201:enzymology; D014170:Transformation, Genetic; D017962:alpha-Linolenic Acid / Q000378:metabolism
D054883:Oxylipins; D010940:Plant Proteins; D018749:RNA, Plant; D017962:alpha-Linolenic Acid; D019787:Linoleic Acid; D006591:Hexobarbital; D044943:Fatty Acid Desaturases; C078565:omega-3 fatty acid desaturase
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