TOLERANCE OF AVENA-SATIVA TO THE ALLELOCHEMICAL BENZOXAZOLINONE - DEGRADATION OF BOA BY ROOT-COLONIZING BACTERIA

A rapid degradation of 2-(3H)-benzoxazolinone (BOA) in aqueous media b y root-colonizing bacteria of Avena sativa is described. 2-Amino-3H-ph enoxazin-3-one and 2-acetylamino-3H-phenoxazin-3-one were identified a s microbial decomposition products. o-Aminophenol was detected as an i ntermediate. This microbial degradation was also observed when roots o f Secale cereale were incubated in aqueous 0.5 mM BOA solutions in con trast to Triticum aestivum and Vicia faba. With Avena sativa phytotoxi c effects of 0.125 mM and 0.25 mM 2-amino-3H-phenoxazin-3-one were pro ved by radicle elongation assays. Nevertheless, the inhibitory influen ce of BOA is significantly reduced due to the microbial degradation pr ocess. The possible physiological importance of the species dependent microbial metabolization of this allelochemical is discussed.