Fig. 2

Ultrastructure of phloem cells in storage root of cassava showing highly dense plasmodesmata. a–c, d–f, g–i, j–l Phloem cells in the primary fibrous root and storage root at the early, middle, and late stages, respectively. a, g, j a partial enlargement of b, h and k respectively. c, f, i, l Arrows indicated plasmodesmata between two PCs in the primary fibrous root and storage root at the early, middle, and late stages, respectively. d, e Plasmodesmata between a PC and adjacent CC cell, between SE and CC in early storage roots respectively. h, k A larger scope of the transverse section of the phloem cell group in the storage root at the middle and late stages. CW in k indicates a thickened cell wall. All of them were with cropped edges and adjusted position using Adobe Photoshop CS6.0 software. Abbreviations, SE, sieve element; CC, companion cell; PC, parenchyma cell; CW, cell wall