title: Laser photoacoustic detection allows in planta detection of nitric oxide in tobacco following challenge with avirulent and virulent Pseudomonas syringae Pathovars.
abstract: We demonstrate the use of laser photoacoustic detection (LPAD) as a highly sensitive method to detect in planta nitric oxide ((*)NO) production from tobacco (Nicotiana tabacum). LPAD calibration against (*)NO gas demonstrated a linear relationship over 2 orders of magnitude with a detection threshold of <20 pmol h(-1) (1 part per billion volume [ppbv]). The specificity of the photoacoustic signal for (*)NO when adding gas or the (*)NO donor, sodium nitroprusside, on injection into plant leaves, was demonstrated by its abolition with O(3) ((*)NO + O(3) --> NO(2) + O(2)). The utility of the LPAD method was shown by examination of a nonhost hypersensitive response and a disease induced by Pseudomonas syringae (P. s.) pv phaseolicola and P. s. pv tabaci in tobacco. (*)NO was detected within 40 min of challenge with P. s. pv phaseolicola, some 5 h before the initiation of visible tissue collapse. The wildfire tobacco pathogen P. s. pv tabaci initiated (*)NO generation at 2 h postinfection. The use of (*)NO donors, the scavenger CPTIO ([4-carboxyphenyl]-4,5-dihydro-4,4,5,5-tetramethyl-3-oxide), and the mammalian nitric oxide synthase inhibitor l-NMMA (N(G)-monomethyl-l-arginine) indicated that (*)NO influenced the kinetics of cell death and resistance to both avirulent and virulent bacteria in tobacco. These observations suggest that (*)NO is integral to the elicitation of cell death associated with these two bacterial pathogens in tobacco.
authors: Institute of Biological Sciences, University of Wales, Aberystwyth, SY23 3DA, Wales, United Kingdom. lum@aber.ac.uk
authors: Luis A J
authors: LA
authors: Mur
authors: I Edi
authors: IE
authors: Santosa
authors: Lucas J J
authors: LJ
authors: Laarhoven
authors: Nicholas J
authors: NJ
authors: Holton
authors: Frans J M
authors: FJ
authors: Harren
authors: Aileen R
authors: AR
authors: Smith
mesh_terms: D000162:Acoustics; D002245:Carbon Dioxide / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism; D007834:Lasers; D008027:Light; D009569:Nitric Oxide / Q000378:metabolism*; D010935:Plant Diseases / Q000382:microbiology; D044224:Pseudomonas syringae / Q000254:growth & development / Q000472:pathogenicity*; D014026:Nicotiana / Q000378:metabolism* / Q000469:parasitology*; D014774:Virulence
chemical_list: D005030:Ethylenes; D002245:Carbon Dioxide; D009569:Nitric Oxide; C036216:ethylene