Interspecific differentiation and phylogenetic relationships of poison ryegrass (Lolium temulentum L.) and Persian darnel (L. persicum Boiss. & Hohen. ex Boiss.)

Abstract

To clarify the speciation and evolution of the inbreeding Lolium spp., poison ryegrass and Persian darnel, we analyzed genetic relationships using microsatellite and AFLP markers among accessions from Pakistan, where both species grow sympatrically or parapatrically. Dendrograms were constructed using the unweighted pair-group method with arithmetic averages (UPGMA), based on simple matching coefficient of similarity among 29 accessions of poison ryegrass and 16 accessions of Persian darnel. Most of the poison ryegrass and Persian darnel accessions were genetically divided into two clusters. One and two chloroplast RFLP (restriction fragment length polymorphism) haplotypes were identified in poison ryegrass and Persian darnel accessions, respectively, from Pakistan, which correspond to each cluster or subcluster of dendrograms. Some accessions, morphologically identified as Persian darnel, belong to neither poison ryegrass nor Persian darnel clusters and locate in other cluster between them. Because this intermediate group had the same haplotype as poison ryegrass, shared almost all alleles with poison ryegrass and/or Persian darnel, and was genetically closer to poison ryegrass than to Persian darnel, we hypothesize that the intermediate group was derived maternally from poison ryegrass via hybridization with Persian darnel.