title: Nitric oxide accelerates seed germination in warm-season grasses.
abstract: The nitric oxide (NO) donor sodium nitroprusside (SNP) significantly promoted germination of switchgrass (Panicum virgatum L. cv Kanlow) in the light and in the dark at 25 degrees C, across a broad range of concentrations. SNP also promoted seed germination in two other warm-season grasses. A chemical scavenger of NO inhibited germination and blocked SNP stimulation of seed germination. The phenolic (+)-catechin acted synergistically with SNP and nitrite in promoting seed germination. Acidified nitrite, an alternate NO donor also significantly stimulated seed germination. Interestingly, sodium cyanide, potassium ferricyanide and potassium ferrocyanide at 200 microM strongly enhanced seed germination as well, whereas potassium chloride was without effect. Ferrocyanide and cyanide stimulation of seed germination was blocked by an NO scavenger. Incubation of seeds with a fluorescent NO-specific probe provided evidence for NO production in germinating switchgrass seeds. Abscisic acid (ABA) at 10 microM depressed germination, inhibited root elongation and essentially abolished coleoptile emergence. SNP partially overcame ABA effects on radicle emergence but did not overcome the effects of ABA on coleoptile elongation. Light microscopy indicated extension of the radicle and coleoptiles in seeds maintained on water or on SNP after 2 days. In contrast, there was minimal growth of the radicle and coleoptile in ABA-treated seeds even after 3-4 days. These data indicate that seed germination of warm-season grasses is significantly influenced by NO signaling pathways and document that NO could be an endogenous trigger for release from dormancy in these species.
authors.affiliation: USDA-ARS, 344A Keim Hall and Department of Agronomy and Horticulture, East Campus, University of Nebraska, Lincoln, NE 68583-0937, USA. gsarath1@unl.edu
authors.forename: Gautam
authors.initials: G
authors.lastname: Sarath
authors.forename: Paul C
authors.initials: PC
authors.lastname: Bethke
authors.forename: Russell
authors.initials: R
authors.lastname: Jones
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Baird
authors.forename: Guichuan
authors.initials: G
authors.lastname: Hou
authors.forename: Robert B
authors.initials: RB
authors.lastname: Mitchell
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D002392:Catechin / Q000494:pharmacology; D018548:Cotyledon / Q000254:growth & development; D003497:Cyclic N-Oxides / Q000494:pharmacology; D005292:Ferricyanides / Q000494:pharmacology; D005295:Ferrocyanides / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D018525:Germination / Q000187:drug effects; D007093:Imidazoles / Q000494:pharmacology; D008027:Light; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009573:Nitrites / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D008897:Panicum / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D006109:Poaceae / Q000187:drug effects / Q000254:growth & development; D012621:Seasons; D012639:Seeds / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D013696:Temperature
chemical_list: D003497:Cyclic N-Oxides; D005292:Ferricyanides; D005295:Ferrocyanides; D016166:Free Radical Scavengers; D007093:Imidazoles; D020030:Nitric Oxide Donors; D009573:Nitrites; C007931:hexacyanoferrate III; D009599:Nitroprusside; C079391:2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; D009569:Nitric Oxide; D000040:Abscisic Acid; D002392:Catechin; C020354:hexacyanoferrate II