Cross‐compatibility of Triticeae species indigenous to Japan and cytogenetics of F1 hybrids

Cross-compatibility of Agropyron ciliare Franch. var. minus Ohwi (2n = 4x = 28) and A. tsukushiense Ohwi var. iransiens Ohwi (2n = 6x = 42), as female, with Triticum L., Aegilops L., Secale L., Haynaldia Schur., Hordeum L. and amphiploid, genera of Triticeae, was studied. Embryo rescue was necessary because of abortive endosperm in all combinations. Rate of seed set was higher in combinations involving A. ciliare than in A. tsukushiense, and with Hordeum than with Triticum. Out of 13,013 florets pollinated and 1332 embryos cultured, a total of 319 F, (2.5 % and 24.1 %, respectively) was produced. The F, of the cross involving barley (H. vulgare, H. irregulare, 2n = 2x = 14) snowed chromosome instability. In the F, A. tsukushiense x barley, chromosome numbers varied from 2n = 21, the haploid number of A. tsukushiense, to 2n = 56, although many somatic cells had 2n = 4x = 28, the expected chromosome number. Besides chromosome instability, all the F, plants from A. ciliare x barley showed hybrid weakness.