Second locus of peptidase as a marker for genetic investigations of Phytophthora infestans [Antrasis peptidazės lokusas kaip žymiklis genetiniuose Phytophthora infestans tyrimuose]. – Botanica Lithuanica, 9(3): 275–283

Second locus of peptidase (Pep-2) is useful, cheap, and technically quite a simple marker that can be used for comparative analysis of Phytophtora infestans strains and populations. This polymorphic locus is represented by two alleles 100 and 112; all their combinations commonly occur in the field populations. Genetic diversity for Pep-2 locus in the majority of populations is higher than for Pep-1. The use of Pep-2 in the complex with other markers such as mating type and Pep-1 has potential in the investigations of clonal structure of populations, the ways of spreading of the pathogen, and possible sources of infection. The complex of aforementioned features is promising for use in regional and interregional databases on late blight agent. The comparative analysis of mating type, Pep-1 and Pep-2 of Russian and Belorussian populations of P. infestans elucidated that the majority of investigated populations had the genotypes A1, 100/100, 100/100; A2, 100/100, 100/100, and A1, 100/100, 100/112. The genotypes ?2, 100/100, 100/112 and ?1, 100/100, 112/112 were rarer. Other possible P. infestans genotypes were found for a few isolates in different populations or were absent.

Keywords: Phytophftora infestans, late blight, analysis of populations, allozyme structure.