Detoxification and Transcriptome Response in Arabidopsis Seedlings Exposed to the Allelochemical Benzoxazolin-2(3H)-one

Abstract

Benzoxazolin-2(3H)-one (BOA) is an allelochemical most commonly associated with monocot species, formed from the O-glucoside of 2,4-dihydroxy-2H-1,4-benzoxazin-3(4H)-one by a two-step degradation process. The capacity of Arabidopsis to detoxify exogenously supplied BOA was analyzed by quantification of the major known metabolites BOA-6-OH, BOA-6-O-glucoside, and glucoside carbamate, revealing that detoxification occurs predominantly through O-glucosylation of the intermediate BOA-6-OH, most likely requiring the sequential action of as-yet-unidentified cytochrome P450 and UDP-glucosyltransferase activities. Transcriptional profiling experiments were also performed with Arabidopsis seedlings exposed to BOA concentrations, representing I 50 and I 80 levels based on root elongation inhibition assays. One of the largest functional categories observed for BOA-responsive genes corresponded to protein families known to participate in cell rescue and defense, with the majority of these genes potentially associated with chemical detoxification pathways. Further experiments using a subset of these genes revealed that many are also transcriptionally induced by a variety of structurally diverse xenobiotic compounds, suggesting they comprise components of a coordinately regulated, broad specificity xenobiotic defense response. The data significantly expand upon previous studies examining plant transcriptional responses to allelochemicals and other environmental toxins and provide novel insights into xenobiotic detoxification mechanisms in plants.

Plants Release Precursors of Histone Deacetylase Inhibitors to Suppress Growth of Competitors

“…When tested in the same concentration range as APO and AMPO, the root-exuded precursor substances DIBOA and DIMBOA and the intermediates BOA and MBOA did not inhibit plant HDACs (Supplemental Figure 5). These results were in line with a previous report that the half-maximal effective concentration (EC 50 ) of BOA in a root growth inhibition assay was 540 µM (Baerson et al, 2005), i.e., a concentration 10 times higher than the effective APO and AMPO concentrations for HDAC inhibition. This suggests that the root-secreted precursor substances need to be metabolized or chemically converted to become potent HDAC inhibitors.…”

Safeners recruit multiple signalling pathways for the orchestrated induction of the cellular xenobiotic detoxification machinery in Arabidopsis

“…Exposure of Arabidopsis seedlings to the allelochemical benzoxazolin-2(3H)-one (BOA), for example, leads to massive changes in gene expression, including the up-regulation of a large number of detoxification genes (Baerson et al 2005), which showed an overlap of only 11.0% with the safener-inducible genes identified in this study. Likewise, only 11.4% of the detoxification genes induced by phytoprostane A1 (PPA1) were represented in our set of safener-inducible genes, as compared with 28% that were co-induced by BOA and PPA1 (Mueller et al 2008).…”

“…In Arabidopsis thaliana, for example, safeners were shown to induce the expression of GSTs and glucosyl transferases (phase II; DeRidder et al 2002;Smith et al 2004;Edwards et al 2005b), glutathione-conjugate transport (phase III; Baerson et al 2005;DeRidder & Goldsbrough 2006) and catabolism (phase IV;Brazier-Hicks et al 2008). Also in hybrid poplar, phase I-III genes were found to be up-regulated after safener treatment (Rishi et al 2004).…”

Respuesta transcripcional de Populus a bifenilos policlorados: Aspectos aplicados a la fitorremediación

“…Además existen numerosas investigaciones que revelan que las MDR no sólo están implicados en la desintoxicación, sino también en la regulación celular de almacenaje (Gaedeke et al, 2001;Fekete et al, 2015;Cummins et al, 2015). Se ha encontrado que AT3G59140 (AtMRP14; MRP14) está inducido más de 2,5 veces (fold change) en respuesta a Benzoxazolinona en Arabidopsis (Baerson et al, 2005).…”

“…Por otro lado, Baerson et al, (2005) y Fode et al, (2008 enfatizaron el rol central de los factores TGA a la respuesta a xenobióticos. El factor de trascripción TGA del tipo STP1 (Potri.009G164300) (N) del análisis de co-expresión podría participar en la ruta de degradación de xenobióticos.…”