(B) Sieve plate P-protein Sieve tube Sieve plate element Lateral sieve Modified plastid Sieve tube 日日日 element Companion Smooth ell endoplasmic reticulum Branched Cytoplasm plasmodesma Plasma Vacuole membrane Chloroplast Figure 6-1 Thickened一 primary wall Nucleus Sieve plate pore Mitochondria Sieve plate
Figure 6-1
Middle lamella Figure 6-2 lasma membrane Protein particles on outer leaflet of er ell wall ooplast cytoplasm Endoplasmic reticulum acute plasmodesma Protein particles on Desmotubule Protein particles on inner leaflet of Er with appressed ER inner leaflet of plasma membrane
Figure 6-2
Plasma membrane Cytoplasm Endoplasmic reticulum Desmotubule Central rod Desmotubule St Cell wall Plasma membrane Cell wall Middle lamella Central cavit Cytoplasmic sieeve Cross sections I FIGURE 1.27 Plasmodesmata between cells. (A) Electron micrograph of a wall separating two adjacent cells, showing the plasmodesmata. (B)Schematic view of a cell wall with Central cavity two plasmodesmata with different shapes. The desmotubule is continuous with the ER of the adjoining cells. Proteins line Central rod the outer surface of the desmotubule and the inner surface of Cytoplasmic Spokelike the plasma membrane; the two surfaces are thought to be sleeve filamentous connected by filamentous proteins. The gap between the pro proteins teins lining the two membranes apparently controls the mol- ecular sieving properties of plasmodesmata. (A from Tilney et al. 1991: B after Buchanan et al. 2000.) igure 6-2-1
Figure 6-2-1
Acquiring phloem sap. Aphids are small insects that remove nutrients from phloem by means of a needlelike mouthpart called a stylet a Aphid with stylet in place. b When the experimenter removes the aphids body, phloem sap is available for 50 collection and analysis. stylet Figure 6-4
Figure 6-4
Mouthpart Sieve the Mouthpart 25m Aphids used to study translocation in phloem. (a)Mature aphid, a tiny insect about 3 to 6 mm in length, feeding on a stem. (b) LM of phloem cells, showing a sieve tube member that has been penetrated by the aphid mouthpart (a, Dwight Kuhn; b, M.H. Zimmerman, Science, Vol. 133, pp. 73-79 (Fig 4), 13 Jan. Figure 6-4-1 1961. Copyright 2002 by the American Association for the Advancement of Science)
Figure 6-4-1