Effect of pH and Auxin on Chloride Uptake into Avena Coleoptile Cells.

The effect of pH on (36)Cl(-) movement into coleoptile cells (Avena sativa L. cv. Garry) was investigated and compared with effects of indoleacetic acid. (36)Cl(-) uptake, but not efflux, is stimulated when coleoptile sections are placed in media adjusted to pH levels from 5 to 3 after a preincubation period at pH 6.5. The enhancement is seen within 2 minutes, is not correlated with growth, and is completely erased by respiratory inhibitors. In comparison to the acid-induced stimulation, the stimulatory effect of indoleacetic acid on (36)Cl(-) uptake is also not accompanied by accelerated efflux, and indoleacetic acid does not further stimulate (36)Cl(-) uptake into 1-millimeter sections beyond that seen at pH 3.5 without auxin.