Buscot, F

Frettinger, P

Herrmann, S

Oelmüller, Ralf

We used a culture system and 55 cDNA fragments regulated in the total root system of oak microcuttings premycorrhizal with Piloderma croceum to compare gene regulation in lateral roots four weeks after fungal infection or after the application of exogenous indole-3-acetic acid (IAA). 67% of these genes responded to the treatments. The fungus regulated 58% and IAA 31% of the genes. All genes which responded to Piloderma croceum were upregulated, while up- and down-regulated genes were observed after IAA treatment. Although only one developmental stage and a sole IAA dose were analysed, 20% of the genes responded to both treatments even if not in the same way, suggesting that the complex premycorrhizal effects of Piloderma croceum and auxin partially activate the same genes. Regulation of genes encoding calmodulin and calcium ATPase in both treatments indicate that calcium flow could also play a role for EM formation in our system.

570-578