Effects of Glyphosate on Ultrastructure and Photosynthesis of Pellia epiphylla

A thallous liverwort Pellia epiphylla was sprayed with glyphosate (N-phosphonomethyl-glycine) at different concentrations and then cultivated at three different temperatures. The effects of the herbicide were studied by measuring net photosynthesis and by ultrastructural observation of epidermal cells. Glyphosate caused a rapid decrease in photosynthetic activity and in the ability of the process to react quickly to light variations. The inhibition of net photosynthesis was strong during the first week, tended to reverse during the following weeks, but was increasing again 4-5 weeks after the treatment. Unusual ultrastructural formations were observed in addition to ' normal' senescing symptoms 1 day after treatment; vesicular and tubular structures on the chloroplast surface and at large in the cytoplasm, granular bodies likely to be detached from the chloroplast stroma, deterioration of oil bodies, ER and ribosomes, increase of lipid spherules and vacuolation of cytoplasm. Two weeks after the treatment deterioration of grana formation was also observed, the plasmalemma was disconnected and the length of mitochondrial cristae had increased.