Enzyme polymorphism in Citrullus lanatus and C. colocynthis in Israel and Sinai

Electrophoretic and morphological variation was studied in 13 cultivars of C. lanatus and 31 accessions of C. colocynthis from Israel. Twelve enzyme systems were assayed, representing 19 loci. We found 12 commercially grown cultivars to be monomorphic at all loci. One C. lanatus accession collected from Israel is highly polymorphic and carries alleles of C. colocynthis; this accession is probably a representative of a locally cultivated land race grown by Bedouins for animal feed. Over a range of 500 km two forms of C. colocynthis were identified: one which grows along the coastal plains of the Mediterranean and the other in the arid Negev and Sinal deserts. A high level of electrophoretic and morphological divergence was found between plants of the two regions, whereas within the ecotypes little variation was observed.