Geneviève Chiapusio1, Luís González2, Manuel J. Reigosa-Roger2 and François Pellissier3
1 Laboratoire de ChronoEnvironment – UFR STGI. UMR CNRS 6249 – EA INRA. Université de Bourgogne – Franche Comté. Pôle Universitaire de
Montbéliard. BP 71427. FR-25 211. Montbéliard Cedex. France
2 Dep. Plant Biology and Soil Science, Univ. Vigo (Spain).
3 Laboratoire d´Ecologie Alpine. Centre Interdisciplinaire Scientifique de la Montagne. Université Savoie Mont Blanc., 73376 Le Bourget-du-Lac Cedex. France
Alellochemicals are secondary metabolites released by plants into the environment, generally acting as inhibitors of several physiological processes in the target plants, thus creating sometimes metabolic imbalances that can produce situations that have been found similar to abiotic stress. We call allelopathic stress to the set of challenges that the plant receiving allelochemicals has to face. Stress conditions usually induce an inhibition of protein synthesis (and then, a growth inhibition) and an accumulation of low molecular weight metabolites such as proline and polyamines. Within this framework, objectives were to test phytotoxicity of two known allelochemicals (p-hydroxybenzoic acid and 2-benzoxazolinone) on germination and growth of radish seedlings and identifying substances that could be used as reliable allelopathic stress markers. The most powerful inhibitory allelochemical was 2-benzoxazolinone. Results revealed drastic germination (-50%) and root growth (-40% biomass) inhibitions due to 2-benzoxazolinone 10-3 M. Furthermore, root morphology was different than in control plants, without hairy zone and browncoloured. Allelopathic stress induced by p-hydroxybenzoic acid and 2-benzoxazolinone showed different results in stress markers in radish roots, hypocotyls and cotyledons; total protein content provided only general information about the growth state (enhanced or inhibited), polyamines (spermidine, spermine and putrescine) were ineffective whereas proline was found to be the most reliable allelopathic stress marker.
Keywords: 2-benzoxazolinone, allelopathy, p-hydroxybenzoic acid, Raphanus sativus, stress
Abbreviatons: 2-benzoxazolinone (BOA), p-hydroxybenzoic acid (POH), polyamines (Pas), Spermidine (Spd), Putrescine (Put), Spermine (Spm)
RECEIVED: November 17, 2015
ACCEPTED December 21, 2015