Abstract
When cultured on media containing auxin, hypocotyl explants of Arabidopsis generate adventitious roots. With this phenomenon as a model of de novo organogenesis, we have been engaged in the identification of elementary machineries involved in it. Here we introduce a series of temperature-sensitive mutants defective in adventitious root formation (rid1 to 5, rpd1, rgd1 to 3) and summarize the results of analyses on these mutants.
Analyses on mutant phenotypes, including lateral root formation and callus formation, have related defects caused by these mutations to the following steps of adventitious root formation: acquisition of competence for cell proliferation (rid1); resumption of cell division (rid2); development of root primordium (rpd1); establishment of root apical meristem (rid1); maintenance of cell proliferation (rgd1 and rgd2); growth of adventitious root (rgd3). The rid5 mutant required higher auxin concentrations for initiating root and callus formation at the restrictive temperature, implying a deficiency in auxin signaling.
