Isoenzyme evidence on the systematics ofHordeum sectionMarina (Poaceae)

Morphological differentiation of diploid accessions ofHordeum marinum Huds. s.l. into two varieties, var.marinum and var.fouilladei (Rouy)Nevski is associated with isoenzyme differentiation. The tetraploid form ofH. marinum s.l. exhibited fixed heterozygosity of several heterozymes with one homoeozyme shared with var.fouilladei and the second homoeozyme not found in the two diploids. It also differed from both diploids in the mobility of glucose-6-phosphate dehydrogenase. All three taxa differed in morphs of EST-A. It is concluded that the tetraploid is an allopolyploid with one genome closely related to the diploid var.fouilladei and with the second genome divergent from those of both diploids by genes for unique morphs of eight homoeozymes. On the basis of the isoenzyme data, three phylogenetic sibling species—H. marinum Huds. s.str. (2x),H. geniculatum All. s.str. (= var.fouilladei, 2x), andH. caudatum Jaaska, spec. nova (4x), are proposed within theH. marinum s.l. complex and a key is given.