Intergeneric hybridization between Agropyron tsukushiense and Hordeum bulbosum (4X).

Abstract

In order to obtain polyhaploids in genus Agropyron by the bulbosum method, nine species were pollinated by Hordeum bulbosum (4x). Among progenies obtained by embryo culture, six plants did not show elimination of any chromosomes derived from H. bulbosum and were intergeneric hybrids between A. repens or three ecotypes of A. tsukushiense and H. bulbosum. Out of six hybrids obtained, two plants of A. tsukushiense EE-4 or ST-1× H. bulbosum (4x) (2n=34 or 2n=35) were examined morphologically and cytologically. These hybrids were shorter, but had numerous tillers. They were completely sterile. The spike morphology resembled female parent rather than intermediate between parents. Several characteristics of pollen parent were also observed in these hybrids. The average chromosome pairing per cell at MI of PMCS in A. tsukushiense EE-4 and ST-1×H. bulbosum hybrids was 2.8II+28.4I and 4.6II+25.8I, respectively. The loosely associated bivalent formation, a rare occurrence of cells with more than seven bivalents, and absence of multivalent association in these hybrids suggest a lack of segmental homology among chromosome complements of three genomes of A. tsukushiense and two of H. bulbosum.The production of these intergeneric hybrids suggests that genome balance hypothesis proposed in interspecific hybrids of Hordeum can not beapplicable to intergeneric hybrids between Agropyron and H. bulbosum.