Flagellin from an incompatible strain of Acidovorax avenae mediates H2O2 generation accompanying hypersensitive cell death and expression of PAL, Cht-1, and PBZ1, but not of Lox in rice.
Acidovorax avenae causes a brown stripe disease in monocot plants. We recently reported that a rice-incompatible strain of A. avenae caused hypersensitive cell death in rice and that the flagellin of the incompatible strain was involved in this response. The incompatible strain induced the rapid generation of H2O2 accompanying hypersensitive cell death and the expression of defense genes such as PAL, Cht-1, PBZ1, and LOX, whereas the compatible strain did not. The purified incompatible flagellin also induced the expression of PAL, Cht-1, and PBZ1, but LOX expression was not induced by the incompatible flagellin. PAL and LOX enzymatic activities were increased by inoculation with the incompatible strain, whereas only PAL activity was increased by the incompatible flagellin. Interestingly, the flagellin-deficient incompatible strain lost the ability to generate H2O2 and induce hypersensitive cell death, but PAL, Cht-1, and PBZ1 expression still were induced by inoculation with the deficient strain, suggesting that induction of these genes is regulated not only by flagellin but also by some other signal. Thus, the incompatible flagellin of A. avenae is a specific elicitor in rice, but it is not the only factor capable of inducing the rice defense system.
Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5, Takayama Ikoma, Nara 630-0101, Japan.
Noriko
N
Tanaka
Fang-Sik
FS
Che
Naohide
N
Watanabe
Satsuki
S
Fujiwara
Seiji
S
Takayama
Akira
A
Isogai
D017209:Apoptosis / Q000235:genetics*; D002478:Cells, Cultured; D002688:Chitinases / Q000235:genetics / Q000378:metabolism; D005408:Flagellin / Q000302:isolation & purification / Q000378:metabolism*; D005656:Fungal Proteins; D018506:Gene Expression Regulation, Plant; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007113:Immunity, Innate / Q000235:genetics; D008084:Lipoxygenase / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D010650:Phenylalanine Ammonia-Lyase / Q000235:genetics / Q000378:metabolism; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D010940:Plant Proteins / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D011549:Pseudomonas / Q000254:growth & development* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013844:Thiazoles / Q000494:pharmacology
D005656:Fungal Proteins; C099062:PBZ1 protein, Oryza sativa; D010940:Plant Proteins; D012333:RNA, Messenger; D013844:Thiazoles; C053376:pathogenesis-related proteins, plant; D005408:Flagellin; C099063:oryzemate; D006861:Hydrogen Peroxide; D008084:Lipoxygenase; D002688:Chitinases; C101191:Cht1 protein, Candida albicans; D010650:Phenylalanine Ammonia-Lyase