Foliar application of an experimental plant growth regulator, N,N-bis(phosphonomethyl)glycine (glyphosine) caused chlorosis of emerging leaves of maize seedlings. These bleached leaf segments had reduced levels of chloroplastic 70-S ribosomes and chloroplastic ribosomal RNA. In the same segments, there was no effect on the level of 80-S cytoplasmic ribosomes. Ultrastructural studies showed that chloroplasts in these tissues had reduced levels of grana stacking. Glyphosine had no effects on the light-induced electron transport and phosphorylation activities of isolated chloroplasts.
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