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 Th inopyrum curvifolium (Lange) D.R. Dewey, T scirpeum (K. Presl) D.R. De wey, 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 geni culata ssp. scythica (Nevski) A. Love, were made and chromosome pairin g at metaphase I was studied. The karyotype analyses of mitotic cells stained by aceto-orcein were conducted for both hybrids and the four t arget species. The Giemsa C-banding following acetocarmine staining wa s carried out for the above species and the triploid hybrid T curvifol ium X T bessarabicum (Savul & Rayss) A. Love. Meiotic data indicate th at 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) genom e, designated as j(b3) and J(b4), rather than two J(e) genomes as prev iously believed. Thinopyrum scirpeum and T. elongatum (4x) have simila r 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 jun ceiforme, which has the j(b2) j(e2) genome formula. However, the two s pecies differ in C-banding patterns, reflecting their geographical sep aration. Thinopyrum junceum is a hexaploid with two pairs of j(b2) gen omes 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.