Immunofluorescence and electron microscopic investigations of DCPA-treated oat roots

Immunofluorescence and electron microscopy were used to investigate the effects of DCPA (dimethyl tetrachloroterephthalate) on oat roots. Phragmoplast microtubule arrays were the most consistently affected. Multiple phragmoplasts, undulated phragmoplasts, branched phragmoplasts, and phragmoplasts arising at places other than that predicted by the preprophase band were all observed. Cell wall formations resulting from these abnormal phragmoplast configurations are also abnormal and consist of reticulate cell plates, walls formed at abnormal angles, and wall material in net-like arrays containing pockets of cytoplasm. Cortical and preprophase band microtubule arrays were unaffected, and were similar in both treated and control cells. Minispindle and multipolar spindles were observed in some meristematic cells, although many spindle formations were normal or nearly so. Some multiple and highly lobed nuclei were also found as a consequence of these abnormal divisions. Cell plates were abnormal even when there were no nuclear abnormalities that would cause physical disruption of the division plane and even though preprophase bands (which are predictive of the subsequent plane of division) were normal. These data indicate that DCPA has a direct effect on phragmoplast microtubule organizing centers.