Characterization of 1,3-beta-glucanase and 1,3;1,4-beta-glucanase genes from Phytophthora infestans.

Three putative exo-1,3-beta-glucanase genes (Piexo1, Piexo2, Piexo3), one endo-1,3-beta-glucanase (Piendo1) and one endo-1,3;1,4-beta-glucanase (Piendo2) gene were cloned and characterized from the oomycete Phytophthora infestans. Southern hybridization revealed that Piexo1, Piexo2, Piexo3, and Piendo2 are single copy, and that Piendo1 is encoded by two copies. Furthermore, the analyses showed that for each gene, one or two closely related gene family members were present. The genes contain no introns. Nucleotide sequence analysis of the promoter regions (200nt upstream of ATG start codon) showed that the regions have 56-81% similarity to a 16-nt core sequence hypothesized to be the initiation of transcription point in oomycetes. The predicted molecular weights (32-83kDa), iso-electric points (4.2-6.7) and amino acid sequences of the five proteins are diverse. All the genes are expressed in in vitro grown mycelia and sporangia, as well as during infection of potatoes. Further, Piendo1 and Piendo2 are also expressed in germinating cysts, and Piendo2 in zoospores.