Genetic modification of alternative respiration has differential effects on antimycin A-induced versus salicylic acid-induced resistance to Tobacco mosaic virus.
Salicylic acid (SA), a natural defensive signal chemical, and antimycin A, a cytochrome pathway inhibitor, induce resistance to Tobacco mosaic virus (TMV). Pharmacological evidence suggested signaling during resistance induction by both chemicals involved alternative oxidase (AOX), sole component of the alternative respiratory pathway (AP). Roles of the AP include regulation of intramitochondrial reactive oxygen species and maintenance of metabolic homeostasis. Transgenic tobacco (Nicotiana tabacum) with modified AP capacities (2- to 3-fold increased or decreased) showed no alteration in phenotype with respect to basal susceptibility to TMV or the ability to display SA-induced resistance to systemic viral disease. However, in directly inoculated tissue, antimycin A-induced TMV resistance was inhibited in plants with increased AP capacities, whereas SA and antimycin A-induced resistance was transiently enhanced in plant lines with decreased AP capacities. We conclude that SA-induced TMV resistance results from activation of multiple mechanisms, a subset of which are inducible by antimycin A and influenced by AOX. Other antiviral factors, potentially including the SA-inducible RNA-dependent RNA polymerase, are regulated by AOX-independent mechanisms.
Gilliland
Androulla
A
Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom.
Singh
Davinder P
DP
Hayward
Jennifer M
JM
Moore
Catherine A
CA
Murphy
Alex M
AM
York
Caroline J
CJ
Slator
Jo
J
Carr
John P
JP
D000968:Antimycin A / Q000494:pharmacology*; D019069:Cell Respiration / Q000187:drug effects / Q000235:genetics; D024101:Mitochondrial Proteins; D010088:Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics / Q000821:virology*; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins; D030821:Plants, Genetically Modified; D020156:Salicylic Acid / Q000494:pharmacology*; D014026:Nicotiana / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism / Q000821:virology*; D014027:Tobacco Mosaic Virus / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D000099188:Alternative Oxidase
D000968:Antimycin A; D024101:Mitochondrial Proteins; D010088:Oxidoreductases; D010940:Plant Proteins; D020156:Salicylic Acid; D000099188:Alternative Oxidase