Abstract
Root hair formation is induced at low pH condition in lettuce seedlings. Decrease of Manganese (Mn) uptake involved in this phenomenon. Transverse cortical microtubules (CMTs) array suppressed root hair formation. CMTs randomization induced root hair initiation at low-pH condition and completed within 30 minutes after low pH treatment. In this study, we investigated whether CMT randomized before root hair induction by decrease of Mn uptake.
CMTs of at least 70 % of root epidermal cells at 1.2 - 1.5 mm above the tip were randomized by 2 hours incubation in 0 mM Mn at pH 6, which is root hair inducible condition. On the other hand, CMT randomization was suppressed to approximately 10 % of root epidermal cells by 1 hour incubation in 3 mM Mn at pH4, which root hair formation was suppressed. The induction of CMT randomization and root hair formation brought by 0 mM Mn were suppressed by the addition of 10-6 M PCIB. The suppression of CMT randomization and root hair formation brought by 3 mM Mn were recovered by the addition of 10-7 M IAA. These data suggested that the decrease of Mn uptake at low pH induced CMT randomization via auxin.
