Abstract
Low-pH (pH4) treatment can induce root hair formation in lettuce seedlings. Disarrangement of transverse cortical microtubule (CMT) arrays is essential for this phenomenon. CMT randomization is mediated by auxin and ethylene. We investigated the role of microfilaments (MF) in low-pH-induced root hair formation.
Actin-depolymerizing drug cytochalasinB or polymerizing drug jasplakinolide suppressed root hair initiation. These suppressions were never released by addition of IAA or ethylene precursor ACC. CMT randomization induced by actin drugs was not recovered by addition of neither auxin inhibitor PCIB nor ethylene inhibitor AVG. At pH6, colchicine-induced disruption of CMT brought root hair formation. Colchicine-induced root hair formation was inhibited by PCIB or AVG. The inhibitory effect of AVG was recovered by IAA but that of PCIB was not recovered by ACC.
These data show that low-pH-induced root hair formation requires polymerization and de-polymerization of MF, disintegration of transverse CMT arrays, and auxin.
