Light regulates symplastic communication in etiolated corn seedlings

The effect of light on symplastic communication in dark grown maize seedlings was tested using the symplastic probe carboxyfluorescein. Prior white-light irradiation stimulated longitudinal transport of carboxyfluorescein in the mesocotyl stele of dark-grown seedlings. The stimulation was multiphasic with a positive followed by a negative phase. Lateral transport from the stele into the mesocotyl cortex was inhibited by the prior white-light irradiation. The inhibitory effect of prior white-light irradiation on lateral transport was completely photo-modulatable by terminal farred and far-red/red irradiations, suggesting the involvement of phytochrome. The stimulatory effect of the prior white irradiation observed for the stele, however, was not photoreversible. It is suggested that environmental factors, such as light, might modulate growth and development, in part, by modulating symplastic cell to cell communication and thus the distribution of nutrients and growth regulators.