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Avr-Rps gene expression in an incompatible soybean-Phytophthora sojae interaction: the influence of silicon

Aliyeh Rasoolizadeh: Université Laval

<div>Silicon (Si) is reported to offer protection to plants, particularly against biotrophic and hemibiotrophic pathogens; however, the mechanisms underlying this phenomenon are unknown. In the soybean-<em>Phytophthora sojae</em> interaction, Si has been shown to confer incompatibility between the plant and pathogen. Similarly, the expression of <em>Avr</em> genes in <em>P. sojae</em> triggers the expression of corresponding soybean <em>Rps</em> (Resistance to <em>P. sojae</em>) genes and leads to resistant phenotypes. The objective of this study was to exploit the incompatible <em>P. sojae</em>-soybean pathosystem to investigate how Si fertilization affects the expression of <em>Rps-Avr</em> genes as a means to test the hypothesis that the deposition of Si in the extracellular matrix (apoplast) interferes with effector-receptor expression. Based on phenotypic responses, both Si-treated and -deprived plants showed resistant phenotypes when they were inoculated with <em>P. sojae</em> carrying an <em>Avr</em> gene associated with the corresponding <em>Rps</em> gene in soybean plants. However, based on the expression of <em>Avr-Rps</em> genes, it appears that a differential expression under Si treatment, especially at 4 dpi, would indicate that different mechanisms are at work to explain the incompatible interactions. These results could contribute to explain the elusive prophylactic properties of Si against plant pathogens.</div>