Diversity of Polyketide Synthase Genes in lichen Cladonia spp.

Abstract

Lichens are well known to produce a great variety of secondary metabolites including polyketides which have diverse biological roles and potential uses in pharmaceutical application. To attain a comprehensive understanding of polyketide synthase (PKS) gene diversity of lichen species from polar regions, forty-two Cladonia samples were selected from Chile, the Artic and the Antarctic regions. The β-ketosynthase (KS) domains of putative PKS genes were amplified and sequenced using degenerate primers. We obtained 25 KS sequence fragments from direct sequencing and 33 fragments from cloning. Phylogenetic analyses of 58 KS sequences have shown that 10 distinct PKS types were retrieved, of which all belonged to non-reducing (NR) PKS. Three and six types were included in NR clade I and clade II, respectively. The last type of PKS was related to NR type I and type II, but the specific relationship was not resolved well. The most abundant PKS type consisted with 30 sequences from 23 samples (and the second most abundant type contained 13 sequences from 10 samples).The sample with the most diverse PKS types was included Cladonia furcata. It contained 8 types of PKS, two of which belonged to NR clade I and the other six types belonged to NR clade II.