Further evidence for cell wall deposition during graft formation

Cells of Sedum telephoides undergoing lethal cellular senescence in response to grafting with Solanum pennellii often possess plasmalemmal tubules (PT). The PT are unbranched, 27-31 nm in diameter, and are bordered by a wall measuring 4.8-5.2 nm in thickness. No regular substructure is discernible in the lumen of the PT. At 36 h after grafting PT extend into the cytoplasm of Sedum cells at the graft interface between Sedum and Solanum. By 10 days after grafting, however, PT are found embedded in newly deposited cell wall. These results indicate that cell wall deposition occurs during the early stages of graft development.