Tracing the wild genetic stocks of crop plants

Genetic distance analysis was recently utilized to suggest Morocco as a centre of origin of domesticated barley (Hordeum vulgare L.) (Molina-Cano et al. 1999). The main problem with this contention has to do with the identification of the so-called wild barley (Hordeum spontaneum C. Koch) from Morocco. These populations were collected in a restricted area in the Djebel Siroua range, where they grow exclusively in cultivated fields and never spread into the adjacent natural habitats dominated by the wild desert plant Artemisia herba-alba Asso. (Molina-Cano et al. 1982). Moreover, in their analysis these authors included a tough rachis type, indicating their failure to take into account the differences between wild and domesticated plant forms. Yet another disturbing point (in addition to the title), is the conclusion suggesting Morocco as a possible centre of origin of cultivated barley. It is hard to understand how the high level of internal similarity of the Moroccan barley, which is likely to be a mere result of a founder effect (Ladizinsky 1985), supports such a conclusion. Recently, AFLP markers were used to estimate genetic distance between wild and cultivated barley (Badr et al. 2000). In this study, accessions from Israel, Jordan, Lebanon, Syria, Turkey, Iraq, Iran, northern Africa, central Asia, and the Himalayas were compared. Interestingly, the hypothesis of Molina-Cano et al. (1999) regarding Morocco as a center of origin of cultivated barley was not confirmed by Badr et al. (2000). Based on their DNA marker analyses, Badr et al. (2000) suggest that certain populations in the central and northern parts of Israel along with several Jordanian populations are the possible origin of cultivated barley. Inspection of the number of Israeli and Jordanian accessions versus the numbers of lines from the rest of the geographic regions relative to the actual area of the respective territories reveals the following: Israel and Jordan, while holding less than one thirtieth of the area of the other regions, are represented by 132 wild accessions. The remainder of the wild barley distribution range (including northern Africa, central Asia, the Himalayas, Turkey, Iran, Iraq, Syria, and Lebanon) are represented by 185 accessions. Had the Israeli-Jordanian wild barley genepool been represented by merely 6 lines in accordance with its relative area, what might have been the result? Moreover, it looks as if Badr et al. (2000) refrained from comparing their results w