Distribution and expression of elicitin genes in the interspecific hybrid oomycete Phytophthora alni.

Phytophthora alni subsp. alni (Paa), P. alni subsp. multiformis (Pam) and P. alni subsp.uniformis (Pau) are responsible for alder disease in Europe. Class I and II elicitin genes patterns of Paa, Pam, Pau and the phylogenetically close species P. cambivora and P.fragariae were studied through mRNA sequencing and 3’ untranslated region (3’UTR)-specific PCRs and sequencing. The occurrence of multiple 3’UTR sequences in association to identical elicitin encoding sequences in Paa indicated duplication/recombination events. The mRNA pattern displayed by Paa demonstrated that elicitin genes from all the parental genomes are actually expressed in this allopolyploid taxon. The complementary elicitin patterns resolved confirmed the possible involvement of Pam and Pau in the genesis of the hybrid species Paa. The occurrence of multiple and common elicitin genes sequences throughout P. cambivora, P. fragariae and P. alni sensu lato, not observed in other Phytophthora species, suggests that duplication of these genes occurred before the radiation of these species