Changes in dihydroxymethoxybenzoxazinone glycoside content in wheat plants infected by three plant pathogenic fungi
1995
Weibull, J. | Niemeyer, H.M.
Hydroxamic acids (Hx), present among members of the family Gramineae, defend the plant against several insect species and some bacteria. Their role in defence against fungal pathogens is still unclear. We tested the hypothesis that the mode of infection by the fungus influences the release from DIMBOA-glucoside, the main Hx in wheat, of the more active aglycone DIMBOA. Infection by the pathogenic necrotroph Septoria tritici resulted in significant hydrolysis of DlMBOA-glucoside in seedlings of two wheat cultivars differing in Hx concentrations. Infection by Drechslera teres, a necrotroph non-compatible with wheat but pathogenic on barley, caused only a slight reduction of glucoside concentration. The content of aglycone did not increase concurrently in any of these experiments. No change in glucoside content was evident following infection by the obligate parasite Puccinia recondita. In vitro, S. tritici was able to increase by 39% the rate at which DIMBOA disappeared from aqueous solutions. Free DIMBOA was not detected in roots of plants infected with S. tritici, but there was a tendency for glucoside levels to be higher than in roots of control plants.
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