Interaction of pollen-specific actin-depolymerizing factor with actin

We have examined the interaction of recombinant lily pollen ADF, LIADF1, wi th actin and found that whilst it bound both G- and F-actin, it had a much smaller effect on the polymerization and depolymerization rate constants th an the maize vegetative ADF, ZmADF3. An antiserum specific to pollen ADF, a ntipADF, was raised and used to localize pollen ADF in daffodil - a plant i n which massive reorganizations of the actin cytoskeleton have been seen to occur as pollen enters and exits dormancy. We show, for the first time, an ADF decorating F-actin in cells that did not result from artificial increa se in ADF concentration. In dehydrated pollen this ADF:actin array is repla ced by actin:ADF rodlets and aggregates of actin, which presumably act as a storage form of actin during dormancy. In germinated pollen ADF has no spe cific localization, except when an adhesion is made at the tip where actin and ADF now co-localize. These activities of pollen ADF are discussed with reference to the activities of ZmADF3 and other members of the ADF/cofilin group of proteins.