RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISMS REVEAL CONSIDERABLE NUCLEARDIVERGENCE WITHIN A WELL-SUPPORTED MATERNAL CLADE IN ALLIUM SECTION CEPA (ALLIACEAE)

Maternal phylogenies estimated by restriction fragment length polymorp hisms (RFLPs) in the chloroplast DNA (cpDNA) delineated a well-support ed clade containing Allium altaicum, A. cepa (bulb onion), A. fistulos um (Japanese bunching onion), A. galanthum, and A. vavilovii. Few poly morphic restriction-enzyme sites were detected among the wild and cult ivated species within this clade, and relationships could not be confi dently estimated. Random nuclear RFLPs revealed considerable Variation among these species and three distinct groups were identified (Altaic um, Cepa, and Galanthum). Relationships were estimated using principal components and cluster analyses of the Jaccard's similarity matrix. F or five out of six analyses, nuclear phylogenies estimated by UPGMA an d neighbor joining of the Jaccard's similarity matrix produced a weakl y supported monophyletic lineage for A. altaicum, A. fistulosum, and A . galanthum, disagreeing with maternal phylogenies that produced a wea kly supported monophyletic lineage for A. altaicum, A. fistulosum, A. cepa, and A. vavilovii. Allium oschaninii was closely related to A. ga lanthum and these two species may represent the progenitor types. Over all, restriction-enzyme analyses of the nuclear and cpDNA produced few synapomorphies among closely related species in Allium section Cepa.