Abstract
Light and existence of shoot are essential for low pH (pH 4) induced root hair formation (RHF) in lettuce. In intact seedlings, the role of light could be substituted by chlorogenic acid (CGA). In dark-grown decapitated seedlings, addition of both CGA and sugar were required for RHF. These results suggested that sugar moved from shoot to root and promoted RHF in cooperation with CGA. To examine the relation between sugar and RHF, sugar contents (glucose and fructose) in lettuce root were determined.
RHF, which was induced by CGA in dark-grown intact seedlings at low pH, could be observed 4 hr after CGA application and ceased within 24 hr. Sugar contents in the roots also increased ca. twofold of the initial level at 4 hr and decreased to 1/2 of the initial level at 24 hr. Sugar contents in the roots of dark-grown intact seedlings at pH 6 and of dark-grown decapitated seedlings of pH 4 or 6 determined at 4 hr were approximately equal to the initial level. Seedlings cultured in these conditions showed no RHF by the application of CGA. These results indicated a strong correlation between RHF and sugar contents in lettuce root.
