Phylogenetic reconstruction at the species and intraspecies levels in the genus Pisum (L.) (peas) using a histone H1 gene

A phylogenetic analysis of the genus Pisum (peas), embracing diverse wild and cultivated forms, which evoke problems with species delimitation, was carried out based on a gene coding for histone H1, a protein that has a long and variable functional C-terminal domain. Phylogenetic trees were reconstructed on the basis of the coding sequence of the gene His5 of H1 subtype 5 in 65 pea accessions. Early separation of a clear-cut wild species Pisum fulvum is well supported, while cultivated species Pisum abyssinicum appears as a small branch within Pisum sativum. Another robust branch within P. sativum includes some wild and almost all cultivated representatives of P. sativum. Other wild representatives form diverse but rather subtle branches. In a subset of accessions, PsbA-trnH chloroplast intergenic spacer was also analysed and found less informative than His5. A number of accessions of cultivated peas from remote regions have a His5 allele of identical sequence, encoding an electrophoretically slow protein product, which earlier attracted attention as likely positively selected in harsh climate conditions. In PsbA-trnH, a 8 bp deletion was found, which marks cultivated representatives of P. sativum.

► A histone H1 gene well resolves phylogeny of Pisum even at intraspecies level.
► Early separation of P. fulvum supported, ‘P. abyssinicum’ appears within P. sativum.
► An earlier recognised branch including wild and cultivated P. sativum supported.
► A H1–5 variant found in colder regions is encoded by an identical allele.
► PsbA-trnH chloroplast intergenic spacer is less informative than a histone H1 gene.