Identifying Auxin Biosynthetic Mutants in Arabidopsis thaliana

As a plant hormone, auxin controls numerous developmental, growth, and regulatory processes of the plants and is a necessary compound for the maintenance of plant stem cells. While the roles of auxin in plants have been studied thoroughly, the auxin biosynthetic pathway is not completely understood. The following approaches were used in attempt to identify specific genes involved in this pathway: 100,000 EMS (ethyl methanesulfonate) mutagenized plants were screened for auxin deficient phenotypes. These phenotypes included long roots and lack of apical hooks in three-day-old seedlings grown on media containing ethylene and short roots on media containing natural auxin IAA. Since the mutagenized plants also harbored a transgene for an auxin response reporter DR5:GFP, root meristems of 10-day-old seedlings were examined for auxin responses using fluorescent microscopy: the fate of stem cells was analyzed. The plant lines that showed loss of root meristems and reduced or abnormal DR5:GFP expression were transferred to soil for propagation and genetic crossing. The study resulted in the identification of 7 potential mutants.