title: Strboh A homologue of NADPH oxidase regulates wound-induced oxidative burst and facilitates wound-healing in potato tubers.
abstract: During 30-months of storage at 4 degrees C, potato (Solanum tuberosum L.) tubers progressively lose the ability to produce superoxide in response to wounding, resist microbial infection, and develop a suberized wound periderm. Using differentially aged tubers, we demonstrate that Strboh A is responsible for the wound-induced oxidative burst in potato and aging attenuates its expression. In vivo superoxide production and NADPH oxidase (NOX) activity from 1-month-old tubers increased to a maximum 18-24 h after wounding and then decreased to barely detectable levels by 72 h. Wounding also induced a 68% increase in microsomal protein within 18 h. These wound-induced responses were lost over a 25- to 30-month storage period. Superoxide production and NOX activity were inhibited by diphenylene iodonium chloride, a specific inhibitor of NOX, which in turn effectively inhibited wound-healing and increased susceptibility to microbial infection and decay in 1-month-old tubers. Wound-induced superoxide production was also inhibited by EGTA-mediated destabilization of membranes. The ability to restore superoxide production to EGTA-treated tissue with Ca(+2) declined with advancing tuber age, likely a consequence of age-related changes in membrane architecture. Of the five homologues of NOX (Strboh A-D and F), wounding induced the expression of Strboh A in 6-month-old tubers but this response was absent in tubers stored for 25-30 months. Strboh A thus mediates the initial burst of superoxide in response to wounding of potato tubers; loss of its expression increases the susceptibility to microbial infection and contributes to the age-induced loss of wound-healing ability.
authors.affiliation: Postharvest Physiology and Biochemistry Laboratory, Department of Horticulture and Landscape Architecture, Washington State University, Pullman, WA 99164-6414, USA.
authors.forename: G N Mohan
authors.initials: GN
authors.lastname: Kumar
authors.forename: Suresh
authors.initials: S
authors.lastname: Iyer
authors.forename: N Richard
authors.initials: NR
authors.lastname: Knowles
mesh_terms: D002118:Calcium / Q000378:metabolism / Q000502:physiology; D002746:Chlorpromazine / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D008954:Models, Biological; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D009861:Onium Compounds / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D035281:Plant Tubers / Q000235:genetics / Q000378:metabolism*; D016897:Respiratory Burst; D020133:Reverse Transcriptase Polymerase Chain Reaction; D011198:Solanum tuberosum / Q000201:enzymology* / Q000235:genetics; D013314:Stress, Mechanical; D013481:Superoxides / Q000378:metabolism; D013997:Time Factors
chemical_list: D009861:Onium Compounds; D010940:Plant Proteins; D013481:Superoxides; C007517:diphenyleneiodonium; D004492:Edetic Acid; D019255:NADPH Oxidases; D002118:Calcium; D002746:Chlorpromazine