ibclogo XVI International Botanical Congess


Abstract Number: 6021
Session = 5.2.5


MACROMOLECULAR TRAFFICKING VIA PLASMODESMAL IS DEVELOPMENTALLY REGULATED


K. Oparka1, A.G. Roberts1, P. Boevink1, S. Santa Cruz1, I. Roberts1, K.S. Pradel1, I. Imlau2, N. Sauer2, A. Katz3, G. Kotlizky3 & B.L. Epel3, 1Scottish Crop Res. Inst., Dundee, 2 Lehrstuhl Bot. II, Univ. Erlangen-Nurnberg, 3 Dept. Plant Sci., Univ. Tel Aviv


Plasmodesmata (Pd) are membranous tunnels that interconnect plant cells forming an intercellular communication network. Initial studies showed that Pd conductivity was limited to molecules smaller than 1 kDa. Recent investigations suggested that plants possess a trafficking system for facilitating movement via Pd of select endogenous RNAs and proteins. We show using biolistic bombardment of plasmids encoding GFP and GFP-fusion proteins that proteins of up to 53 kDa pass through sink-leaf Pd. During the sink to source transition Pd permeability decreases. When GFP (27kDa) is synthesized in companion cells in source leaves of transgenic plants under the control of the Arabidopsis sucrose transport protein AtSUC2, GFP loads into sieve elements and is translocated to sink regions of the plant where it unloads and spreads cell-to-cell. In young sink leaves, GFP unloads and spreads throughout mesophyll and epidermal cells. In leaves undergoing sink to source transition, GFP unloads in the basal region (sink region) while in the apical region (source) GFP unloading becomes restricted. The data demonstrate that non-specific Amacromolecular trafficking@ is a general feature of simple Pd in sink tissue and that this function is under developmental control.


HTML-Version made 7. July 1999 by Kurt Stüber