Expression of α-DIOXYGENASE 1 in Tomato and Arabidopsis Contributes to Plant Defenses Against Aphids

Abstract

Plant α-dioxygenases (α-DOX) are fatty acid-hydroperoxidases that contribute to the synthesis of oxylipins, a diverse group of compounds primarily generated through oxidation of linoleic (LA) and linolenic acid (LNA). Oxylipins are implicated in plant signaling against biotic and abiotic stresses. We report here that the potato aphid (Macrosiphum euphorbiae) induces Slα-DOX1 but not Slα-DOX2 expression in tomato (Solanum lycopersicum). Slα-DOX1 upregulation by aphids does not require either jasmonic acid (JA) or salicylic acid (SA) accumulation, since tomato mutants deficient in JA (spr2, acx1) or SA accumulation (NahG) still show Slα-DOX1 induction. Virus-induced gene silencing of Slα-DOX1 enhanced aphid population growth in wild-type (WT) plants, revealing that Slα-DOX1 contributes to basal resistance to aphids. Moreover, an even higher percent increase in aphid numbers occurred when Slα-DOX1 was silenced in spr2, a mutant line characterized by elevated LA levels, decreased LNA, and enhanced aphid resistance as compared with WT. These results suggest that aphid reproduction is influenced by oxylipins synthesized from LA by Slα-DOX1. In agreement with our experiments in tomato, two independent α-dox1 T-DNA insertion mutant lines in Arabidopsis thaliana also showed increased susceptibility to the green peach aphid (Myzus persicae), indicating that the role α-DOX is conserved in other plant-aphid interactions.

Arabidopsis thaliana—Myzus persicae interaction: shaping the understanding of plant defense against phloem-feeding aphids

“…Oxidation of fatty acids by α-DOXs yields 2(R)-hydroperoxides, which can be further processed into other products. In Arabidopsis, expression of the α- DOX1 gene was up-regulated in response to GPA infestation (Avila et al, 2013). Similarly, in tomato expression of the Sl α- DOX1 gene was up-regulated in response to potato aphid infestation (Avila et al, 2013).…”

“…In Arabidopsis, expression of the α- DOX1 gene was up-regulated in response to GPA infestation (Avila et al, 2013). Similarly, in tomato expression of the Sl α- DOX1 gene was up-regulated in response to potato aphid infestation (Avila et al, 2013). In both, Arabidopsis and tomato, knock-down of α-DOX1 function resulted in increased susceptibility to aphids.…”

Leaf oil bodies are subcellular factories producing antifungal oxylipins

“…Silencing of a-dioxygenase in N. attenuata produces plants that are smaller than wild type [25], whereas no phenotype was observed for a-dox1 a-dox2 double mutants of A. thaliana [39]. A. thaliana plants lacking a-DOX1 enhances susceptibility to green peach aphid (Myzus persicae) [40]. These results suggest that a-dioxygenase and 2-HOT have functional diversity among different plant species.…”

Membrane Dynamics and Multiple Functions of Oil Bodies in Seeds and Leaves

“…Arabidopsis T-DNA insertion mutants of a-DOX1 are susceptible to green peach aphid (Myzus persicae; Avila et al, 2013). In pepper (Capsicum annuum), virus-induced gene silencing of a-dioxygenase expression confers susceptibility to the bacterial pathogen Xanthomonas axonopodis and suppression of the hypersensitive response (Hong et al, 2017).…”