Effects of Gibberellin on the Arrangement and the Cold Stability of Cortical Microtubules in Epidermal Cells of Pea Internodes

摘要

Longitudinal microtubules are predominant in epidermal cells of the 3rd internodes of dwarf pea (Pisum sativumL. cv. Little Marvel) seedlings. In more than 50of the cells, cortical microtubules are running parallel to the cell axis.GA3promotes elongation of the internodes and gives rise to a predominance of transverse microtubules. In more than 60of the GA3-treatd cells, cortical microtubules are running transverse to the cell axis.Longitudinal microtubules in the GA3-untreated cells are resistant to low-temperature treatment, but transverse microtubules in the GA3-treated cells are sensitive to it. Longitudinal microtubules are present in GA3-treated epidermal cells with low frequency. They are resistant to low-temperature treatment.Longitudinal, oblique and transverse microtubules are present with almost the same frequency in epidermal cells of the 3rd internodes of tall pea (cv. Early Alaska) seedlings. GA3promotes elongation of the internodes also in tall pea seedlings, but it does not alter the direction of cortical microtubules so distinctly as it does in dwarf pea seedlings.As in dwarf pea seedlings, longitudinal microtubules are resistant to low-temperature treatment, and transverse microtubules are sensitive to it in tall pea seedlings.