Abstract
Pumpkin Phloem Protein 16-1 (CmPP16-1) has been characterized as phloem-mobile single-stranded RNA-binding protein. In the whole phloem protein context, CmPP16-1 moves long-distance to shoot and root. We have recently found that root-ward movement of CmPP16-1 became inefficient when CmPP16-1 was purified, suggesting the presence of pumpkin phloem factors that is involved in determining movement destination. To understand how the long-distance movement of CmPP16-1 is regulated, we searched for the interacting proteins of CmPP16-1 from pumpkin phloem sap. Gel-filtration chromatography and co-immunoprecipitation, using anti-CmPP16-1 antibody, demonstrated that CmPP16-1 formed a complex with other phloem sap proteins. Root-ward movement of CmPP16-1 was restored in the presence of these interacting proteins, indicating that these proteins are involved in the movement regulation. This work was partly supported by Grant-in-Aid for Scientific Research in Priority Areas from the Ministry of Education, Culture, Sports, Science, and Technology of Japan (grant No. 15031227) to K.A
