title: Identification and quantitation of compounds in a series of allelopathic and non-allelopathic rice root exudates.
abstract: An investigation of the chemical basis for rice allelopathy to the rice weed arrowhead (Sagittaria montevidensis) was undertaken using GC/MS and GC/MS/MS techniques. Twenty-five compounds were isolated and identified from the root exudates of both allelopathic and non-allelopathic rice varieties. Phenolics, phenylalkanoic acids, and indoles were among the chemical classes identified. Two indoles previously unreported in rice were detected in the exudates, 5-hydroxy-2-indolecarboxylic acid and 5-hydroxyindole-3-acetic acid. Several other compounds identified in this study have not previously been reported in rice root exudates, namely mercaptoacetic acid, 4-hydroxyphenylacetic acid, and 4-vinylphenol. The levels of 15 compounds present in the exudates were quantified using GC/MS/MS. Six of the seven most abundant compounds were phenolic acids. Significant differences exist between the allelopathic and non-allelopathic cultivars in their production of three of these six compounds. Greater amounts of trans-ferulic acid, p-hydroxybenzoic acid, and caffeic acid were detected in the exudates of allelopathic cultivars. The seventh compound, abietic acid, was significantly higher in the non-allelopathic cultivars.
authors.affiliation: Farrer Centre, Charles Sturt University Locked Bag 588 Wagga Wagga, New South Wales, Australia 2678. aseal@csu.edu.au
authors.forename: Alexa N
authors.initials: AN
authors.lastname: Seal
authors.forename: James E
authors.initials: JE
authors.lastname: Pratley
authors.forename: Terry
authors.initials: T
authors.lastname: Haig
authors.forename: Min
authors.initials: M
authors.lastname: An
mesh_terms: D045784:Abietanes / Q000032:analysis; D002109:Caffeic Acids / Q000032:analysis; D003373:Coumaric Acids / Q000032:analysis; D008401:Gas Chromatography-Mass Spectrometry; D062385:Hydroxybenzoates / Q000032:analysis; D007211:Indoles / Q000032:analysis; D012275:Oryza / Q000737:chemistry*; D010616:Phenanthrenes / Q000032:analysis; D010636:Phenols / Q000032:analysis; D010648:Phenylacetates / Q000032:analysis; D010675:Pheromones / Q000032:analysis* / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry*; D013864:Thioglycolates / Q000032:analysis
chemical_list: D045784:Abietanes; D002109:Caffeic Acids; D003373:Coumaric Acids; D062385:Hydroxybenzoates; D007211:Indoles; D010616:Phenanthrenes; D010636:Phenols; D010648:Phenylacetates; D010675:Pheromones; D013864:Thioglycolates; C008070:4-hydroxyphenylacetic acid; C017487:2-mercaptoacetate; C004999:ferulic acid; C040048:caffeic acid; C023710:abietic acid