Induced plant defense responses against chewing insects. Ethylene signaling reduces resistance of Arabidopsis against Egyptian cotton worm but not diamondback moth.
The induction of plant defenses by insect feeding is regulated via multiple signaling cascades. One of them, ethylene signaling, increases susceptibility of Arabidopsis to the generalist herbivore Egyptian cotton worm (Spodoptera littoralis; Lepidoptera: Noctuidae). The hookless1 mutation, which affects a downstream component of ethylene signaling, conferred resistance to Egyptian cotton worm as compared with wild-type plants. Likewise, ein2, a mutant in a central component of the ethylene signaling pathway, caused enhanced resistance to Egyptian cotton worm that was similar in magnitude to hookless1. Moreover, pretreatment of plants with ethephon (2-chloroethanephosphonic acid), a chemical that releases ethylene, elevated plant susceptibility to Egyptian cotton worm. By contrast, these mutations in the ethylene-signaling pathway had no detectable effects on diamondback moth (Plutella xylostella) feeding. It is surprising that this is not due to nonactivation of defense signaling, because diamondback moth does induce genes that relate to wound-response pathways. Of these wound-related genes, jasmonic acid regulates a novel beta-glucosidase 1 (BGL1), whereas ethylene controls a putative calcium-binding elongation factor hand protein. These results suggest that a specialist insect herbivore triggers general wound-response pathways in Arabidopsis but, unlike a generalist herbivore, does not react to ethylene-mediated physiological changes.
Stotz
H U
HU
Department of Genetics and Evolution, Max-Planck-Institute of Chemical Ecology, Carl-Zeiss Promenade 10, 07745 Jena, Germany.
Pittendrigh
B R
BR
Kroymann
J
J
Weniger
K
K
Fritsche
J
J
Bauke
A
A
Mitchell-Olds
T
T
D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D003517:Cyclopentanes / Q000378:metabolism; D005030:Ethylenes / Q000096:biosynthesis / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D007915:Lepidoptera / Q000502:physiology*; D008969:Molecular Sequence Data; D009943:Organophosphorus Compounds / Q000378:metabolism / Q000494:pharmacology; D054883:Oxylipins; D010937:Plant Growth Regulators / Q000378:metabolism; D020156:Salicylic Acid / Q000378:metabolism; D020539:Sequence Analysis, Protein; D015398:Signal Transduction
D003517:Cyclopentanes; D005030:Ethylenes; D009943:Organophosphorus Compounds; D054883:Oxylipins; D010937:Plant Growth Regulators; C011006:jasmonic acid; C036216:ethylene; D020156:Salicylic Acid; C005073:ethephon