Poster: Plant-symbiont interactions

Abs # 589: Characterization of gene expression in the nodulation signaling pathway mutant nsp1 of Medicago truncatula using cDNA microarrays.

Presenter:	Portyanko, Vladimir A, vportyan@biosci.cbs.umn.edu
Authors	Portyanko, Vladimir A (A)   Sharopova, Natalya R (A)   VandenBosch, Kathryn A (A)
Affiliations:	(A): University of Minnesota

A major objective of our DOE-funded project is to characterize mutants of Medicago truncatula defective in rhizobial infection to facilitate the dissection of molecular mechanisms in the symbiosis. As material for this research, three mutants deficient in responses to rhizobia, nsp1, dmi1, and dmi2, were used. We report our results on nsp1, which demonstrates some limited responses to Nod factor (e.g. root hair branching and Ca spiking), but is defective in cortical cell division and shows significantly reduced epidermal nodulin gene expression. Characterization of gene expression in nsp1 was based on microarrays composed of 6,000 well-annotated M. truncatula cDNA clones. The experimental design included comparisons of wild-type phenotype (A17) versus nsp1 in a series of time-course experiments for both uninoculated plants and plants inoculated with Sinorhizobium meliloti (strain ABS7) grown on aeroponics. Time-points included 0, 24, and 48 hours post inoculation or the corresponding developmental stages of plants in uninoculated experiment. The results of the gene expression experiments are discussed, with the emphasis on identification of genes whose rhizobium-modulated expression depends upon NSP1.