Dissecting the Contribution of the Cytoskeleton in Adventitious Root Induction

Unlike the static body skeleton of vertebrates, dynamic cytoskeleton is present in all cells of vertebrates, invertebrates, fungi, lower and higher plants. The dynamicity of the cytoskeleton is expressed by its constant polymerization, depolymerization and rearrangement and is regulated by intrinsic and extrinsic signals. The plant cytoskeleton is composed of two systems of filaments, F-actin and microtubules and associated structural and regulatory proteins. Due to its ability to perceive and transduce signals the cytoskeleton is a central player in various signaling pathways.

Our studies focus on the involvement of cytoskeleton associated proteins in adventitious root (AR) induction. We found that some mutants in cytoskeleton associated proteins had fewer ARs but others had more AR than wild type plants. For example, fewer AR were induced in the mutant mor1-1, in which a temperature-sensitive mutation exist in the MT associated protein (MAP) MOR1, and in bot1-1 a mutant in the MT severing protein katanin. In contrast, the number of AR increased in RIC1-OX3 plants, in which MT bundling is enhanced and katanin is activated. In addition, a triple mutant in three myosin XI genes, 3KO, had more lateral roots (LR) and AR.

The mechanisms underlying the loss or gain of AR induction in these mutants and possible interactions between the two cytoskeletal systems during AR induction will be discussed.