GENOME CONSTITUTIONS OF THINOPYRUM-CURVIFOLIUM, T-SCIRPEUM, T-DISTICHUM, AND T-JUNCEUM (TRITICEAE, GRAMINEAE)

The objective of this study is to elucidate genome constitutions of Thinopyrum curvifolium (Lange) D.R. Dewey, T scirpeum (K. Presl) D.R. Dewey, T distichum (Thunb.) A. Love, and T junceum (L.) A. Love. Hybrids of T sartorii (Boiss. & Heidr.) A. Love with T scirpeum and T junceum, as well as the hybrid between T curvifolium and Pseudoroegneria geniculata ssp. scythica (Nevski) A. Love, were made and chromosome pairing at metaphase I was studied. The karyotype analyses of mitotic cells stained by aceto-orcein were conducted for both hybrids and the four target species. The Giemsa C-banding following acetocarmine staining was carried out for the above species and the triploid hybrid T curvifolium X T bessarabicum (Savul & Rayss) A. Love. Meiotic data indicate that all target species have two sets of the basic genome J(b) but they behave like true allopolyploids because of bivalentization. Karyotypes of T curvifolium and its triploid hybrid with T bessarabicum indicate that T. curvifolium contains two different versions of the j(b) genome, designated as j(b3) and J(b4), rather than two J(e) genomes as previously believed. Thinopyrum scirpeum and T. elongatum (4x) have similar karyotypes. Both are segmental allotetraploids carrying two forms of the J(e) genome. Their genome formulae are j(e2) j(e3) and j(e1) J(e3), respectively. Thinopyrum distichum has a karyotype similar to T junceiforme, which has the j(b2) j(e2) genome formula. However, the two species differ in C-banding patterns, reflecting their geographical separation. Thinopyrum junceum is a hexaploid with two pairs of j(b2) genomes and one pair of the j(e2) genome, and it has a C-banding pattern similar to that of T junceiforme, which has one pair each of the J(b2) and j(e2) genomes.