A comparative study of ancient DNA isolated from charred pea (Pisum sativum L.) seeds from an Early Iron Age settlement in southeast Serbia: inference for pea domestication

The development of agriculture was a key turning point in human history, a central part of which was the evolution of new plant forms, domesticated crops. Grain legumes were domesticated in parallel with cereals and formed important dietary components of early civilizations. First domesticated in the Near East, pea has been cultivated in Europe since the Stone and Bronze Ages. In this study, we present a molecular analysis of ancient DNA (aDNA) extracted from carbonized pea seeds recovered from deposits at Hissar, in southeast Serbia, that date to the eleventh century B.C. Four selected chloroplast DNA loci (trnSG, trnK, matK and rbcL) amplified in six fragments of 128-340 bp with a total length of 1,329 bp were successfully recovered in order to distinguish between cultivated and wild gathered pea. Based on identified mutations, the results showed that genuine aDNA was analyzed. Moreover, DNA analysis resulted in placing the ancient sample at an intermediate position between extant cultivated [Pisum sativum L. and wild P. sativum subsp. elatius (Steven ex M. Bieb.) Asch. et Graebn.]. Consequently, based on a combination of morphological and molecular data, we concluded that the material represents an early domesticated pea. We speculate that Iron Age pea would be of colored flower and pigmented testa, similar to today's fodder pea (P. sativum subsp. sativum var. arvense (L.) Poir.), possibly of winter type. This is the first report of successful aDNA extraction and analysis from any legume species thus far. The implications for pea domestication are discussed here.