Ultrastructural effects and translocation of methyl-2-(4-(2,4-dichlorophenoxy)-phenoxy)propanoate in wheat (Triticum aestivum) and wild oat (Avena fatua)

Abstract

Ultrastructural effects, absorption and translocation of the experimental compound methyl-2-(4-(2,4-dichlorophenoxy)phenoxy)propanoate (MPP), topically applied to resistant wheat (T. aestivum L.) and susceptible wild oat (A. fatua L.), were studied. The 2 spp. were affected differently by MPP when greenhouse-grown seedlings were treated at the 1 1/2-leaf stage. The 2nd leaf of both species was damaged, but wild oat leaves were affected much more than wheat leaves. Although tissues formed after treatment and the apical region of the 2nd leaf of wheat did not appear to be injured, ultrastructural modifications occurred. In wild oat, both visible injury and ultrastructural modifications were seen. Chloroplasts were the organelles most affected by the compound in both species. Cellular alterations ranging from slight to complete destruction of the cytoplasm were observed in cells of treated leaves. Frequently cells with undamaged chloroplasts were located next to cells with damaged chloroplasts. The translocation patterns of [14C]MPP applied as a drop were similar in wheat and wild oat and could not account for the differences in their sensitivities. About 95% of the 14C was recovered in the region of application in both species.