Production and cytogenetic analysis of hybrids between Triticum aestivum and some caespitose Agropyron species

Abstract

Intergeneric hybrids between Triticum aestivum L. cultivars and 12 traditional Agropyron species were produced in variable frequencies, lowest being 0.35% for A. stipaefolium to a high of 41.98% for A. varnense. The crossing success of T. aestivum cultivars ranged from 'Chinese Spring' > 'Pavon-76' = 'Nacozari-75' > 'Fielder' = 'Fremont' > 'Glennson-81'. All F1 hybrids were somatically stable. The new combinations were with A. curvifolium (Thinopyrum curvifolium), A. rechingeri (T. sartorii = rechingeri), A. scythicum (T. scythicum), and A. stipaefolium (Pseudoroegeneria stipaefolia). All hybrids were perennial and possessed a modified phenotype that was intermediate between the parents involved in the hybrid combinations with major variation in spike morphology (elongated spikes with lax internodes). High-pairing hybrids, presumably owing to suppression of the Ph locus were of T. aestivum - A. scythicum (15.31 I + 2.25 II rings + 6.92 II rods + 0.32 III) and T. aestivum - A. stipaefolium (10.6 I + 7.08 II rings + 4.41 II rods + 0.54 III). In the other combinations, the pairing was either low or high, and if high, pairing was attributed to autosyndetic association of the alien genome chromosomes. Based on the meiotic pairing data, alien species that were segmental allotetraploids or partial autopolyploids, or segmental allohexaploids or autoallohexaploids, may be advantageous in developing backcross derivatives with synthetic genomes. Production of fertile amphiploids was restricted to T. aestivum - A. rechingeri. Key words: Triticum aestivum, Agropyron species, Pseudoroegeneria species, Thinopyrum species, intergeneric hybrids, crossability, wide crosses.