Molecular evolution of parasitic plants

VALDOVINOS, TM; SÁNCHEZ PUERTA, M.V.

Mendoza

Congreso; XLVIII Annual Meeting SAIB; 2012

Argentine Society for Biochemistry and Molecular Biology

There are about 4000 parasitic plants, which originated from free-living ancestors in at least eleven independent events during the evolution of angiosperms. Little is known about the genetic changes triggered by the transition to parasitism. Parasitic plants have an intimate association with their hosts and horizontal transfer of genetic material, particularly mitochondrial, has been documented. Our goal is to gain insight into the evolution of the cytoplasmic genomes of understudied lineages of parasitic angiosperms. We collected two holoparasites and four hemiparasites that belong to unrelated angiosperm families. Genomic DNA extractions and PCR amplifications were challenging. We were able to amplify and sequence four mitochondrial genes and the chloroplastic gene rbcL. The mitochondrial genes from parasitic plants showed a high substitution rate and predicted RNA editing sites. Sequences of rbcL showed an average substitution rate (except for Cuscuta sp.) and probably encoded a functional protein. Introns were only detected in the mitochondrial gene cox1. Phylogenetic analyses of each individual gene were performed including sequences from other angiosperms obtained from international databases. Incongruences between the organismal phylogeny and the phylogenies based on individual mitochondrial genes suggested five putative cases of horizontal gene transfer.