title: Narboh D, a respiratory burst oxidase homolog in Nicotiana attenuata, is required for late defense responses after herbivore attack.
abstract: The superoxide (O₂⁻)-generating NADPH oxidases are crucial for the defense of plants against attack from pathogens; however, it remains unknown whether they also mediate responses against chewing insect herbivores. The transcripts of the respiratory burst NADPH oxidase homolog Narboh D in Nicotiana attenuate are rapidly and transiently elicited by wounding, and are amplified when Manduca sexta oral secretions (OS) are added to the wounds. The fatty-acid-amino-acid-conjugates (FACs), demonstrably the major elicitors in M. sexta OS, are responsible for the increase in Narboh D transcripts. Silencing Narboh D significantly reduced reactive oxygen species (ROS) levels after OS elicitation, but neither OS-elicited jasmonic acid (JA) or JA-isoleucine (JA-Ile) bursts, pivotal hormones that regulates plant resistance to herbivores, nor early transcripts of herbivore defense-related genes (NaJAR4 and NaPAL1), were influenced. However, late OS-elicited increases in trypsin proteinase inhibitors (TPIs), as well as the transcript levels of defense genes such as polyphenol oxidase, TPI and Thionin were significantly reduced. In addition, Narboh D-silenced plants were more vulnerable to insect herbivores, especially the larvae of the generalist Spodoptera littoralis. We thus conclude that Narboh D-based defenses play an important role in late herbivore-elicited responses.
authors.affiliation: Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany, Chinese Academy of Science, Lanhei Road 132, China.
authors.forename: Jinsong
authors.initials: J
authors.lastname: Wu
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: Hendrik
authors.initials: H
authors.lastname: Wünsche
authors.forename: Ian T
authors.initials: IT
authors.lastname: Baldwin
mesh_terms: D000818:Animals; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D060434:Herbivory / Q000276:immunology*; D018402:Manduca / Q000502:physiology; D008954:Models, Biological; D019255:NADPH Oxidases / Q000737:chemistry* / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana / Q000201:enzymology* / Q000235:genetics / Q000276:immunology*
chemical_list: D010940:Plant Proteins; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D019255:NADPH Oxidases; C022709:superoxide-forming enzyme