Intergeneric hybrids between Triticum aestivum and three crested wheatgrasses: Agropyron mongolicum, A. michnoi, and A. desertorum

Abstract

Three hybridizations of Triticum aestivum cv. Chinese Spring (CS) (2n = 42) with Agropyron mongolicum (2n = 14), A. michnoi (2n = 28), and A. desertorum (2n = 28) are reported for the first time. Hybrid embryos were obtained at frequencies of 0.24, 1.13, and 2.05%, respectively. The hybrid plants obtained from pollinating CS by A. mongolicum had the expected chromosome number of 2n = 4x = 28, but as a result of hybrid necrosis, none could be raised to the adult stage. Hybrids CS × A. michnoi and CS × A. desertorum both had 2n = 5x = 35 chromosomes. The average meiotic chromosome pairing per cell was 7.04 I + 12.14 II + 1.06 III + 0.07 IV + 0.02 V + 0.02 VI and 9.29 I + 11.05 II + 1.14 III + 0.05 IV, respectively. Their analysis leads to the conclusions that (i) the two Agropyron genomes in the hybrids share a high degree of homology, thus revealing that tetraploid Agropyron species are true autoploids (genome constitution PPPP) and (ii) gene(s) in the Agropyron species suppress the activity of the homoeologous pairing control system of wheat. The possibility of gene transfer from Agropyron to wheat is discussed.Key words: intergeneric hybrids, Triticum aestivum, Agropyron species, hybrid necrosis, chromosome pairing.