Nicotiana attenuata a-DIOXYGENASE1 through its production of 2-hydroxylinolenic acid is required for intact plant defense expression against attack from Manduca sexta larvae

作者：Gaquerel Emmanuel; Steppuhn Anke; Baldwin Ian T^*

来源：New Phytologist, 2012, 196(2): 574-585.

DOI：10.1111/j.1469-8137.2012.04286.x

• alpha-dioxygenase
• herbivory
• jasmonic acid
• oxylipin
• tobacco

Nicotiana attenuata a-DIOXYGENASE1 (a-DOX1) is an oxylipin-forming gene elicited during herbivory by fatty acid amino acid conjugates (FACs) contained in oral secretions of Manduca sexta. To understand the roles of Naa-DOX1 and its major product, 2-hydroxylinolenic acid (2-hydroxylinolenic acid), in N.similar to attenuata%26apos;s anti-herbivore defenses, we used a transgenic line specifically silenced in Naa-DOX1 expression (ir-a-dox1) and monitored 2-HOT production in M.similar to sexta-damaged tissues and its role in influencing the production of direct defense compounds and resistance to this insect. Attack by M.similar to sexta larvae amplified 2-HOT formation at the feeding sites; a reaction probably facilitated by Naa-DOX1%26apos;s high pH optimum which allows 2-HOT formation to occur in the more alkaline conditions at the feeding sites or potentially in the insect mouth parts after the leaf tissue is ingested. Manduca sexta larvae performed better on ir-a-dox1 plants than on wild-type (WT) plants as a result of attenuated herbivory-specific JA and 2-HOT bursts as well as JA-inducible well-established defenses (nicotine, caffeoylputrescine and trypsin proteinase inhibitors). Repeated applications of 2-HOT to wounds before insect feeding partly amplified JA-controlled defenses and restored the resistance of ir-a-dox1 plants. We conclude that 2-HOT, produced by attack-activated a-DOX1 activity, participates in defense activation during insect feeding.

• 出版日期2012-10