Fumonisin B1-induced cell death in arabidopsis protoplasts requires jasmonate-, ethylene-, and salicylate-dependent signaling pathways.
We have established an Arabidopsis protoplast model system to study plant cell death signaling. The fungal toxin fumonisin B1 (FB1) induces apoptosis-like programmed cell death (PCD) in wild-type protoplasts. FB1, however, only marginally affects the viability of protoplasts isolated from transgenic NahG plants, in which salicylic acid (SA) is metabolically degraded; from pad4-1 mutant plants, in which an SA amplification mechanism is thought to be impaired; or from jar1-1 or etr1-1 mutant plants, which are insensitive to jasmonate (JA) or ethylene (ET), respectively. FB1 susceptibility of wild-type protoplasts decreases in the dark, as does the cellular content of phenylalanine ammonia-lyase, a light-inducible enzyme involved in SA biosynthesis. Interestingly, however, FB1-induced PCD does not require the SA signal transmitter NPR1, given that npr1-1 protoplasts display wild-type FB1 susceptibility. Arabidopsis cpr1-1, cpr6-1, and acd2-2 protoplasts, in which the SA signaling pathway is constitutively activated, exhibit increased susceptibility to FB1. The cpr6-1 and acd2-2 mutants also constitutively express the JA and ET signaling pathways, but only the acd2-2 protoplasts undergo PCD in the absence of FB1. These results demonstrate that FB1 killing of Arabidopsis is light dependent and requires SA-, JA-, and ET-mediated signaling pathways as well as one or more unidentified factors activated by FB1 and the acd2-2 mutation.
Asai
T
T
Department of Genetics, Harvard Medical School, and Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
Stone
J M
JM
Heard
J E
JE
Kovtun
Y
Y
Yorgey
P
P
Sheen
J
J
Ausubel
F M
FM
D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D002264:Carboxylic Acids / Q000494:pharmacology*; D016923:Cell Death / Q000187:drug effects; D003517:Cyclopentanes / Q000494:pharmacology; D005030:Ethylenes / Q000494:pharmacology; D037341:Fumonisins; D054883:Oxylipins; D010937:Plant Growth Regulators / Q000494:pharmacology*; D011523:Protoplasts / Q000166:cytology / Q000187:drug effects*; D012459:Salicylates / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*
D002264:Carboxylic Acids; D003517:Cyclopentanes; D005030:Ethylenes; D037341:Fumonisins; D054883:Oxylipins; D010937:Plant Growth Regulators; D012459:Salicylates; C056933:fumonisin B1; C011006:jasmonic acid; C036216:ethylene