A PHYLOGENETIC ANALYSIS OF PISUM BASED ON MORPHOLOGICAL CHARACTERS, AND ALLOZYME AND RAPD MARKERS

Cladistic analyses of 17 wild and cultivated pea taxa were performed u sing morphological characters, and allozyme and RAPD (random amplified polymorphic DNA) markers. Both branch-and-bound and bootstrap searche s produced cladograms that confirmed the close relationships among the wild species and cultivars of Pisum proposed by a variety of systemat ic studies. Intraspecific rankings were supported for northern P. humi le, southern P. humile, P. elatius and P. sativum, which together comp rise a single-species complex. P. fulvum, while clearly the most diver gent of the pea taxa, could also be assigned to the same species compl ex without violating the hierarchial logic of the cladogram. Its inclu sion or exclusion depends on whether the level of interfertility it di splays with other pea taxa or its overall morphological and chromosoma l distinction are emphasized. As suggested by previous studies, northe rn P. humile was the most likely sister taxon to cultivated P. sativum ; although, rigorous phylogenetic evaluation revealed a close genealog ical affinity among P. elatius, northern P. humile and P. sativum. Des pite their limited number, the 16 morphological characters and allozym e markers used precisely organized the pea taxa into established taxon omic groupings, perhaps in part reflecting the role morphology has pla yed historically in pea classification. The RAPD data also generally s upported these same groupings and provided additional information rega rding the relationships among the taxa. Given that RAPDs are relativel y quick and easy to use, are refractory to many environmental influenc es, can be generated in large numbers, and can complement traditional characters that may be limited in availability, they provide a valuabl e new resource for phylogenetic studies.