A 13-lipoxygenase, TomloxC, is essential for synthesis of C5 flavour volatiles in tomato.
C5 volatile compounds, derived from fatty acids, are among the most important contributors to consumer liking of fresh tomatoes. Despite their important roles in flavour, the genes responsible for C5 volatile synthesis have yet to be identified. This work shows that their synthesis is catalysed in part by a 13-lipoxygenase (LOX), TomloxC, the same enzyme responsible for synthesis of C6 volatiles. C5 synthesis is independent of hydroperoxide lyase (HPL); moreover, HPL knockdown significantly increased C5 volatile synthesis. This LOX-dependent, HPL-independent pathway functions in both fruits and leaves. Synthesis of C5 volatiles increases in leaves following mechanical wounding but does not increase in response to infection with Xanthomonas campestris pv. vesicatoria. Large reductions in C5 and C6 volatiles in antisense TomloxC knockdown plants were observed but those reductions did not alter the development of disease symptoms, indicating that these volatiles do not have an important defensive function against this bacterial pathogen.
Horticultural Sciences, University of Florida, PO Box 110690, Gainesville, FL 32611-0690, USA.
Jiyuan
J
Shen
Denise
D
Tieman
Jeffrey B
JB
Jones
Mark G
MG
Taylor
Eric
E
Schmelz
Alisa
A
Huffaker
Dawn
D
Bies
Kunsong
K
Chen
Harry J
HJ
Klee
D053898:Biosynthetic Pathways; D003517:Cyclopentanes / Q000378:metabolism; D015536:Down-Regulation / Q000235:genetics; D005638:Fruit / Q000201:enzymology / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D019787:Linoleic Acid / Q000378:metabolism; D008084:Lipoxygenase / Q000235:genetics / Q000378:metabolism*; D018551:Solanum lycopersicum / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology; D054883:Oxylipins / Q000378:metabolism; D010935:Plant Diseases / Q000382:microbiology; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D013649:Taste; D055549:Volatile Organic Compounds / Q000378:metabolism*; D014974:Xanthomonas / Q000502:physiology; D017962:alpha-Linolenic Acid / Q000737:chemistry / Q000378:metabolism
D003517:Cyclopentanes; D054883:Oxylipins; D010940:Plant Proteins; D055549:Volatile Organic Compounds; D017962:alpha-Linolenic Acid; C011006:jasmonic acid; D019787:Linoleic Acid; C117433:13-lipoxygenase; D008084:Lipoxygenase
13-lipoxygenase; C5 volatiles; Xanthomonas campestris pv. vesicatoria.; hydroperoxide lyase; jasmonic acid; tomato; wounding