Mechanism of inhibition of cytoplasmic streaming by a myosin inhibitor, 2,3-butanedione monoxime

On the basis of the inhibition of myosin by 2,3-butanedione monoxime (BDM), the protein's involvement in various cell activities is discussed. However , it has not been established whether BDM inhibits plant myosin. In the pre sent study, the effect of BDM on isolated plant myosin was analyzed in vitr o. The sliding between myosin from lily (Lilium longiflorum) pollen tubes a nd actin filaments from skeletal muscle was inhibited to 25% at a concentra tion of 60 mM, indicating that BDM can be used as a myosin inhibitor for pl ant materials. Cytoplasmic streaming was completely inhibited by BDM at 30 mM in lily pollen tubes and at 70 mM in short root hair cells, and at 100 m M in long root hair cells of Hydrocharis dubia. However. BDM at high concen trations induced the disorganization of actin filament bundles in lily poll en tubes and short root hair cells. In addition, cortical microtubules were also fragmented in short root hair cells treated with BDM, suggesting a po ssible side effect of BDM.