The whole-plant activation of defense responses to wounding and herbivory requires systemic signaling in which jasmonates （JAs） play a pivotal role. To examine the nature of the slower cell-nonautonomous as compared...The whole-plant activation of defense responses to wounding and herbivory requires systemic signaling in which jasmonates （JAs） play a pivotal role. To examine the nature of the slower cell-nonautonomous as compared to the rapid cell-autonomous signal in mediating systemic defenses in Nicotiana attenuata, reciprocal stem graftingexperiments were used with plants silenced for the JA biosynthetic gene ALLENE OXIDE CYCLASE （irAOC） or plants transformed to create JA sinks by ectopicalIy expressing Arabidopsis JA-O-methyltransferase （ovJMT）. JA-impaired irAOC plants were defective in the cell-nonautonomous signaling pathway but not in JA transport. Conversely, ovJMT plants abrogated the production of a graft-transmissible JA signal. Both genotypes displayed unaltered cell-autonomous signaling. Defense responses （17-hydroxygeranyllinalool diterpene glycosides, nicotine, and proteinase inhibitors） and metabolite profiles were differently induced in irAOC and ovJMT scions in response to graft-transmissible signals from elicited wild type stocks. The performance of Manduca sexta larvae on the scions of different graft combinations was consistent with the patterns of systemic defense metabolite elicitations. Taken together, we conclude that JA and possibly MeJA, but not JA-lle, either directly functions as a long-distance transmissible signal or indirectly interacts with long distance signal（s） to activate systemic defense responses.展开更多
基金the Max-Planck-Society,the Advanced Grant No 293926 of the European Research Council to ITBDFG-funded Collaborative Research Centre “Chemical Mediators in Complex Biosystems-Chem Bio Sys”(SFB 1127) for funding
文摘The whole-plant activation of defense responses to wounding and herbivory requires systemic signaling in which jasmonates （JAs） play a pivotal role. To examine the nature of the slower cell-nonautonomous as compared to the rapid cell-autonomous signal in mediating systemic defenses in Nicotiana attenuata, reciprocal stem graftingexperiments were used with plants silenced for the JA biosynthetic gene ALLENE OXIDE CYCLASE （irAOC） or plants transformed to create JA sinks by ectopicalIy expressing Arabidopsis JA-O-methyltransferase （ovJMT）. JA-impaired irAOC plants were defective in the cell-nonautonomous signaling pathway but not in JA transport. Conversely, ovJMT plants abrogated the production of a graft-transmissible JA signal. Both genotypes displayed unaltered cell-autonomous signaling. Defense responses （17-hydroxygeranyllinalool diterpene glycosides, nicotine, and proteinase inhibitors） and metabolite profiles were differently induced in irAOC and ovJMT scions in response to graft-transmissible signals from elicited wild type stocks. The performance of Manduca sexta larvae on the scions of different graft combinations was consistent with the patterns of systemic defense metabolite elicitations. Taken together, we conclude that JA and possibly MeJA, but not JA-lle, either directly functions as a long-distance transmissible signal or indirectly interacts with long distance signal（s） to activate systemic defense responses.
