CHANGES IN THE FERTILITY AND MEIOTIC BEHAVIOR OF BARLEY (HORDEUM-VULGARE) X WHEAT (TRITICUM-AESTIVUM) HYBRIDS REGENERATED FROM TISSUE-CULTURES

A total of 41 regenerant plants were raised from two consecutive in vitro propagation cycles from a barley (Hordeum vulgare L. cv. Martonvasari 50) x wheat (Triticum aestivum L. cv. Chinese Spring) hybrid. The second-cycle regenerants exhibited great variability for most morphological traits. The female fertility of certain regenerant hybrids considerably exceeded that of the initial hybrid, giving substantially higher seed set when pollinated with wheat. This character was transferred to the BC1 and BC2 progeny produced from the regenerants. The cytological analysis of the second-cycle regenerants indicated that these had a higher degree of meiotic instability than the initial hybrid. The proportion of cells with 28 chromosomes (21 wheat + 7 barley) dropped to one-half of that in the initial hybrid, with a rise in the number of hypoploid and hyperploid cells. The number of chiasmata per cell increased from 1.7 in the initial hybrid to 4.7 in the regenerants, and there was also an increase in the number of misdivisions.