Benzoxazolinone detoxification byN-Glucosylation: The multi-compartment-network ofZea maysL.

Abstract

The major detoxification product in maize roots after 24 h benzoxazolin-2(3H)-one (BOA) exposure was identified as glucoside carbamate resulting from rearrangement of BOA-N-glucoside, but the pathway of N-glucosylation, enzymes involved and the site of synthesis were previously unknown. Assaying whole cell proteins revealed the necessity of H2O2 and Fe(2+) ions for glucoside carbamate production. Peroxidase produced BOA radicals are apparently formed within the extraplastic space of the young maize root. Radicals seem to be the preferred substrate for N-glucosylation, either by direct reaction with glucose or, more likely, the N-glucoside is released by glucanase/glucosidase catalyzed hydrolysis from cell wall components harboring fixed BOA. The processes are accompanied by alterations of cell wall polymers. Glucoside carbamate accumulation could be suppressed by the oxireductase inhibitor 2-bromo-4´-nitroacetophenone and by peroxidase inhibitor 2,3-butanedione. Alternatively, activated BOA molecules with an open heterocycle may be produced by microorganisms (e.g., endophyte Fusarium verticillioides) and channeled for enzymatic N-glucosylation. Experiments with transgenic Arabidopsis lines indicate a role of maize glucosyltransferase BX9 in BOA-N-glycosylation. Western blots with BX9 antibody demonstrate the presence of BX9 in the extraplastic space. Proteomic analyses verified a high BOA responsiveness of multiple peroxidases in the apoplast/cell wall. BOA incubations led to shifting, altered abundances and identities of the apoplast and cell wall located peroxidases, glucanases, glucosidases and glutathione transferases (GSTs). GSTs could function as glucoside carbamate transporters. The highly complex, compartment spanning and redox-regulated glucoside carbamate pathway seems to be mainly realized in Poaceae. In maize, carbamate production is independent from benzoxazinone synthesis.

Recent advances in allelopathy for weed control: from knowledge to applications

“…The resistance of some species to these allelochemicals has been explained by detoxification of the compound by N ‐glucosylation and formation of carbamates and malonyl derivatives . Endophytic fungi such as Fusarium verticillioides seem to be involved in these proceses .…”

“…The resistance of some species to these allelochemicals has been explained by detoxification of the compound by N-glucosylation and formation of carbamates and malonyl derivatives. 192 Endophytic fungi such as Fusarium verticillioides seem to be involved in these proceses. 193 Other aspects studied in the past 12 years include their effect on the structure of the soil microbiota of the wheat rhizosphere, particularly soil-borne pathogenic fungi, which offer an alternative for disease management.…”

Conversions of Benzoxazinoids and Downstream Metabolites by Soil Microorganisms

“…Maize, for instance, can prime DIBOA degradation of GDIBOA (1) by deglucosylation. In this context, the chloroplast-located glucosidases ZmGLU1 and ZmGLU2 (Nestler et al, 2011;Hannemann et al, 2018), may have moonlighting functions when shifted to the apoplast as well as glucosyltransferase BX9 at positions within the cell wall (Schulz et al, 2015(Schulz et al, , 2016.…”

Plant Protection by Benzoxazinoids—Recent Insights into Biosynthesis and Function

“…Indeed, the transgenic expression of the respective UGTs BX8 or BX9 conferred DI(M)BOA tolerance to Arabidopsis [31]. The major detoxification product of BOA in Poales was identified as glucoside carbamate and the biosynthetic steps were defined recently in maize roots [101,102]. Thereby, it has been shown that BX9 is also effective in BOA metabolism.…”