GEOGRAPHIC PATTERNS OF HISTONE-H1 ALLELIC FREQUENCIES FORMED IN THE COURSE OF PISUM-SATIVUM-L (PEA) CULTIVATION

An electrophoretic analysis of histone H1 of Pisum sativum L. was carried out using the collection of 883 accessions of cultivated peas originating from different regions of the Old World. The closely linked genes of five H1 subtypes (2-6) form a cluster, the gene of subtype 1 being located on another chromosome. The fast allelic variant of subtype 1 was not observed to the north of the 44th parallel. The frequency of allele 1 of subtype 5 displays a latitudinal cline and is strongly correlated with the sum of aerial temperatures over the vegetational period. Allele 1 of subtype 6 prevails all over the Old World except Central Asia and China, where allele 3 predominates. From this area allele 3 frequency forms a declining gradient. Alleles of subtypes 2, 3 and 4 exhibit no regularities in their geographic patterns. The data indicate that alleles of H1 subtype 5 and, possibly, subtype 1 in garden pea were subjected to climatically-dependent natural selection under conditions of primitive farming (without conscious selection).