13-Lipoxygenases(LOXs)initiate the synthesis of jasmonic acid(JA),the best-understood oxylipin hormone in herbivory defense.However,the roles of 9-LOX-derived oxylipins in insect resistance remain unclear.Here,we repo...13-Lipoxygenases(LOXs)initiate the synthesis of jasmonic acid(JA),the best-understood oxylipin hormone in herbivory defense.However,the roles of 9-LOX-derived oxylipins in insect resistance remain unclear.Here,we report a novel anti-herbivory mechanism mediated by a tonoplast-localized 9-LOX,ZmLOX5,and its linolenic acid-derived product,9-hydroxy-10-oxo-12(Z),15(Z)-octadecadienoic acid(9,10-KODA).Transposon-insertional disruption of ZmLOX5 resulted in the loss of resistance to insect herbivory.lox5 knockout mutants displayed greatly reduced wound-induced accumulation of multiple oxylipins and defense metabolites,including benzoxazinoids,abscisic acid(ABA),and JA-isoleucine(JA-Ile).However,exogenous JA-Ile failed to rescue insect defense in lox5 mutants,while applications of 1 mM 9,10-KODA or the JA precursor,12-oxo-phytodienoic acid(12-OPDA),restored wild-type resistance levels.Metabolite profiling revealed that exogenous 9,10-KODA primed the plants for increased production of ABA and 12-OPDA,but not JA-Ile.While none of the 9-oxylipins were able to rescue JA-Ile induction,the lox5 mutant accumulated lower wound-induced levels of Ca^(2+),suggesting this as a potential explanation for lower wound-induced JA.Seedlings pretreated with 9,10-KODA exhibited rapid or more robust woundinduced defense gene expression.In addition,an artificial diet supplemented with 9,10-KODA arrested fall armyworm larvae growth.Finally,analysis of single and double lox5 and lox10 mutants showed that ZmLOX5 also contributed to insect defense by modulating ZmLOX10-mediated green leaf volatile signaling.Collectively,our study uncovered a previously unknown anti-herbivore defense and hormonelike signaling activity for a major 9-oxylipin α-ketol.展开更多
Calcium signaling plays a fundamental role in plant immune responses. Various calcium sensors have been characterized to relay and/or decode pathogen-induced calcium signals. Autoimmune mutants are useful resources fo...Calcium signaling plays a fundamental role in plant immune responses. Various calcium sensors have been characterized to relay and/or decode pathogen-induced calcium signals. Autoimmune mutants are useful resources for the dissection of plant immune systems, which have allowed researchers to access in-depth mechanisms of defense signaling. Recent discoveries in this rapidly evolved field have revealed new elements that could help understand the signaling mechanisms mediated by the nucleotide-binding oligomerization domain-like receptors （NLRs）. Here, we briefly overview calcium signaling mutants that exhibit autoimmune phenotypes and focus on discussing AtSR1/CAMTA3-regulated immune signaling, especially how this calcium sensor acts as a guardee monitored by NLR proteins.展开更多
基金supported by United States Department of Agriculture(USDA)-National Institute of Food and Agriculture(NIFA)2017-67013-26524 and 2021-67013-33568 grants awarded to M.V.K.
文摘13-Lipoxygenases(LOXs)initiate the synthesis of jasmonic acid(JA),the best-understood oxylipin hormone in herbivory defense.However,the roles of 9-LOX-derived oxylipins in insect resistance remain unclear.Here,we report a novel anti-herbivory mechanism mediated by a tonoplast-localized 9-LOX,ZmLOX5,and its linolenic acid-derived product,9-hydroxy-10-oxo-12(Z),15(Z)-octadecadienoic acid(9,10-KODA).Transposon-insertional disruption of ZmLOX5 resulted in the loss of resistance to insect herbivory.lox5 knockout mutants displayed greatly reduced wound-induced accumulation of multiple oxylipins and defense metabolites,including benzoxazinoids,abscisic acid(ABA),and JA-isoleucine(JA-Ile).However,exogenous JA-Ile failed to rescue insect defense in lox5 mutants,while applications of 1 mM 9,10-KODA or the JA precursor,12-oxo-phytodienoic acid(12-OPDA),restored wild-type resistance levels.Metabolite profiling revealed that exogenous 9,10-KODA primed the plants for increased production of ABA and 12-OPDA,but not JA-Ile.While none of the 9-oxylipins were able to rescue JA-Ile induction,the lox5 mutant accumulated lower wound-induced levels of Ca^(2+),suggesting this as a potential explanation for lower wound-induced JA.Seedlings pretreated with 9,10-KODA exhibited rapid or more robust woundinduced defense gene expression.In addition,an artificial diet supplemented with 9,10-KODA arrested fall armyworm larvae growth.Finally,analysis of single and double lox5 and lox10 mutants showed that ZmLOX5 also contributed to insect defense by modulating ZmLOX10-mediated green leaf volatile signaling.Collectively,our study uncovered a previously unknown anti-herbivore defense and hormonelike signaling activity for a major 9-oxylipin α-ketol.
基金This research was supported by the US National Science Foundation （ grants 1021344 and 1557813）, the National Natural Science Foundation of China （ grant U1130304）, and USDA NIFA （WNP00321 and WNP00833）.
文摘Calcium signaling plays a fundamental role in plant immune responses. Various calcium sensors have been characterized to relay and/or decode pathogen-induced calcium signals. Autoimmune mutants are useful resources for the dissection of plant immune systems, which have allowed researchers to access in-depth mechanisms of defense signaling. Recent discoveries in this rapidly evolved field have revealed new elements that could help understand the signaling mechanisms mediated by the nucleotide-binding oligomerization domain-like receptors （NLRs）. Here, we briefly overview calcium signaling mutants that exhibit autoimmune phenotypes and focus on discussing AtSR1/CAMTA3-regulated immune signaling, especially how this calcium sensor acts as a guardee monitored by NLR proteins.
