title: Phytochrome B-mediated activation of lipoxygenase modulates an excess red light-induced defence response in Arabidopsis.
abstract: Lipoxygenase (LOX), a non-haem-iron-containing dioxygenase, is activated under various biotic or abiotic stresses to trigger a series resistance response, but the molecular mechanism of LOX activation remains unclear. This work investigated the activation of LOX during the plant defence response induced by excess red light (RL). In conditions of RL-induced defence, Arabidopsis LOX activity and transcription levels of LOX2, LOX3, and LOX4 were both upregulated. Under RL, phytochrome B promoted the degradation of phytochrome-interacting factor 3 (PIF3), a factor that inhibited the expression levels of LOXs, and thus the transcription levels of LOX2, LOX3, and LOX4 were increased. Upon pathogen infection, the activity of mitogen-activated protein kinase 3 (MPK3) and MPK6 was increased in plants pre-treated with RL. Moreover, experiments with the inhibitor PD98059 and mutants mpk3 and mpk6-2 demonstrated that MPK3 and MPK6 were both responsible for LOX activation. Further results showed that, in response to RL, an increase in cytoplasmic calcium concentration and upregulation of calmodulin 3 (CaM3) transcript level occurred upstream of MPK3 and MPK6 activation. Collectively, these results suggested that activation of LOX both at the transcript level and in terms of activity modulates the defence response induced by RL, providing a new insight into the mechanistic study of LOX during plant defences.
authors.affiliation: MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, PR China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, PR China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhou
authors.affiliation: MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, PR China xingda@scnu.edu.cn.
authors.forename: Da
authors.initials: D
authors.lastname: Xing
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000276:immunology / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002147:Calmodulin / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D008027:Light; D008084:Lipoxygenase / Q000235:genetics / Q000378:metabolism; D058945:Lipoxygenases / Q000235:genetics* / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D051939:Phytochrome B / Q000378:metabolism*; D016133:Polymerase Chain Reaction
chemical_list: D029681:Arabidopsis Proteins; D002147:Calmodulin; D051939:Phytochrome B; D058945:Lipoxygenases; C095864:lipoxygenase 3; D008084:Lipoxygenase; D020928:Mitogen-Activated Protein Kinases
keywords: Arabidopsis; MAPK; defence response; excess red light; lipoxygenase; phytochrome B.