The FATTY ACID DESATURASE2 Family in Tomato Contributes to Primary Metabolism and Stress Responses1[OPEN]

• Published in: Plant physiology (Bethesda) Vol. 182; no. 2; pp. 1083 - 1099
• Main Authors: Lee, Min Woo, Padilla, Carmen S., Gupta, Chirag, Galla, Aravind, Pereira, Andy, Li, Jiamei, Goggin, Fiona L.
• Format: Journal Article
• Language: English
• Published: American Society of Plant Biologists 25-11-2019
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.19.00487

A gene family that is required for synthesis of polyunsaturated fatty acids also contributes to aphid resistance in tomato.
The conversion of oleic acid (C18:1) to linoleic acid (C18:2) in the endoplasmic reticulum is critical to the accumulation of polyunsaturated fatty acids in seeds and other tissues, and this reaction is catalyzed by a Δ12-desaturase, FATTY ACID DESATURASE2 (FAD2). Here, we report that the tomato (
Solanum lycopersicum
) genome harbors two genes,
SlFAD2-1
and
SlFAD2-2
, which encode proteins with in vitro Δ12-desaturase activity. In addition, tomato has seven divergent FAD2 members that lack Δ12-desaturase activity and differ from canonical FAD2 enzymes at multiple amino acid positions important to enzyme function. Whereas
SlFAD2-1
and
SlFAD2-2
are downregulated by biotic stress, the majority of divergent
FAD2
genes in tomato are upregulated by one or more stresses. In particular,
SlFAD2-7
is induced by the potato aphid (
Macrosiphum euphorbiae
) and has elevated constitutive expression levels in
suppressor of prosystemin-mediated responses2
(
spr2
), a tomato mutant with enhanced aphid resistance and altered fatty acid profiles. Virus-induced gene silencing of
SlFAD2-7
in
spr2
results in significant increases in aphid population growth, indicating that a divergent
FAD2
gene contributes to aphid resistance in this genotype. Thus, the
FAD2
gene family in tomato is important both to primary fatty acid metabolism and to responses to biotic stress.