ACTIN AND MYOSIN DURING POLLEN GERMINATION

Actin and myosin from pollen tubes of Lilium davidii were studied by u sing immunoblotting, Dot-Blot and myosin Ca2+-ATPase analysis. On immu noblotting of the total soluble pollen tube proteins, anti-a-actin ant ibody labelled a polypeptide approximately 43 ku, which is considered to be the actin of lily. The mRNA encoding actin in ungerminated polle n and germinated pollen were both undetectable in our experiments. A m yosin exhibited Ca2+-ATPase activity, with a native molecular weight o f 460 ku has been identified by using immunoblotting. A polypeptide of about 205 ku and a polypeptide of about 20 ku were the heavy chain an d a set of light chain of the myosin, which can crossreact with anti-s keletal muscle myosin heavy chain monoclonal antibody and anti-skeleta l muscle myosin light chain (20 ku) monoclonal antibody, respectively. The Ca2+-ATPase activities of myosin in crude extracts of germinated pollen were positively related to the growth rates of pollen tubes.