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SUMMARY Bioengineering efforts to increase oil in non‐storage vegetative tissues, which constitute the majority of plant biomass, are promising sustainable sources of renewable fuels and feedstocks. While plants typically do not accumulate significant amounts of triacylglycerol (TAG) in vegetative tissues, we report here that the expression of a plastid‐localized phospholipase A1 protein, DEFECTIVE IN ANTHER DEHISCENCE1 (DAD1), led to a substantial increase in leaf TAG in Arabidopsis. Using an inducible system to control DAD1 expression circumvented growth penalties associated with overexpressing DAD1 and resulted in a rapid burst of TAG within several hours. The increase of TAG was accompanied by the formation of oil bodies in the leaves, petioles, and stems, but not in the roots. Lipid analysis indicated that the increase in TAG was negatively correlated with plastidial galactolipid concentration. The fatty acid (FA) composition of TAG predominantly consisted of 18:3. Expression of DAD1 in thefad3fad7fad8mutant, devoid of 18:3, resulted in comparable TAG accumulation with 18:2 as the major FA constituent, reflecting the flexiblein vivosubstrate use of DAD1. The transient expression of either Arabidopsis DAD1 orNicotiana benthamianaDAD1 (NbDAD1) inN. benthamianaleaves stimulated the accumulation of TAG. Similarly, transgenic soybeans expressing Arabidopsis DAD1 exhibited an accumulation of TAG in the leaves, showcasing the biotechnological potential of this technology. In summary, inducible expression of a plastidial lipase resulted in enhanced oil production in vegetative tissues, extending our understanding of lipid remodeling mediated by DAD1 and offering a valuable tool for metabolic engineering. 

Abstract The basal level of the plant defense hormone jasmonate (JA) in unstressed leaves is low, but wounding causes its near instantaneous increase. How JA biosynthesis is initiated is uncertain, but the lipolysis step that generates fatty acid precursors is generally considered to be the first step. Here, we used a series of physiological, pharmacological, genetic, and kinetic analyses of gene expression and hormone profiling to demonstrate that the early spiking of JA upon wounding does not depend on the expression of JA biosynthetic genes in Arabidopsis (Arabidopsis thaliana). Using a transgenic system, we showed how decoupling the responses to wounding and JA prevents the perpetual synthesis of JA in wounded leaves. We then used DEFECTIVE IN ANTHER DEHISCENCE1 (DAD1) as a model wound-responsive lipase to demonstrate that although its transient expression in leaves can elicit JA biosynthesis to a low level, an additional level of activation is triggered by wounding, which causes massive accumulation of JA. This wound-triggered boosting effect of DAD1-mediated JA synthesis can happen directly in damaged leaves or indirectly in undamaged remote leaves by the systemically transmitted wound signal. Finally, protein stability of DAD1 was influenced by wounding, α-linolenic acid, and mutation in its catalytic site. Together, the data support mechanisms that are independent of gene transcription and translation to initiate the rapid JA burst in wounded leaves and demonstrate how transient expression of the lipase can be used to reveal changes occurring at the level of activity and stability of the key lipolytic step.