Poster: Intercellular Signaling

Abs # 798: The development of quantitative tools for measuring changes in the coefficient of conductivity for Pd induced by developmental, biotic and abiotic signals

Presenter:	Epel, Bernard L., blepel@post.tau.ac.il
Authors	Epel, Bernard L. (A)   Liarzi, Orna  (A)
Affiliations:	(A): Tel Aviv University, Department of Plant Sciences

The regulation of intercellular and inter-organ communication is pivotal for cell fate decisions in plant development and probably plays a significant role in the systemic regulation of gene expression and in defense reactions against pathogens or other biotic and abiotic environmental factors. In plants, symplasmic cell-to-cell communication is provided by plasmodesmata (Pd), coaxial membranous quai-organelles that span cell walls interconnecting adjacent cytoplasms. Macromolecules, proteins and RNA, may be targeted to Pd either non-specifically or via a specific recruitment mechanism. Quantitative tools were developed which have allowed us to quantitatively measure the coefficient of conductivity for Pd, C^Pd, and to determine quantitatively changes in the coefficient induced by developmental, biotic and abiotic signals. The coefficient of conductivity of Pd in sink and source leaves of wild type and of transgeic leaves of N. benthamiana expressing movement protein of Tobacco mosaic virus (MP) incubated both in dark and light and at 16 and 25 ^oC was determined. Pd in source leaves conduct macromolecules; C^{sink Pd}> C^{source Pd} (all conditions). Light down regulated Pd conductivity (all conditions); down regulation was stronger for sink cells. There was no statistically significant general effect of temperature. The effect of MP was dependent on temperature and leaf development. At 16 ^oC, MP down regulates Pd conductivity for both sink and source leaves. At 25 ^oC MP has no significant effect on C^Pd.