Abstract
It has been demonstrated that some pumpkin phloem proteins moved long distance in the organ-selective manner when introduced into rice sieve tube via insect stylet (Aoki et al., Plant Cell Physiol. 43: s192). Here we report the identification and primary structure analysis of pumpkin phloem sap proteins showing organ-selective long-distance movement. Biotinylated protein spots corresponding to long-distance movement signals were excised from 2D-electrophoresis of Q-sepharose bound fraction of the pumpkin phloem sap protein, and excised spots were subjected to in-gel digestion. Peptide fragments were then separated by micro HPLC and their primary structures were determined by internal peptide sequencing and peptide mass analysis. The protein moved specifically to the shoot was identical to the CmPP16-1. One of the two proteins which moved both to the shoot and root was identified as CmPP16-2, and the other was Cucurbita maxima ortholog of silver leaf whitefly inducible protein 1 (SLW1).