[Cytogenetic analysis of alloplasmic recombinant lines (H. vulgare)-T. aestivum with unstable fertility and...

Comparative cytogenetic analysis was performed with four alloplasmic recombinant (Hordeum vulgare)-Triticum aestivum lines differing in morphological traits, number of seeds per spike, and seed plumpness. None of the lines displayed introgression of the barley genetic material: the karyotypes included only common wheat chromosomes. Two lines, 79(B) and 79(D), were cytogenetically stable. Plants of lines 79(A) and 79(C) displayed a high frequency of unbalanced chromosome aberrations, including dicentric and polycentric chromosomes, terminal deletions varying in size, acentric fragments, and multiple unidentifiable translocations. Previous studies of the mitochondrial genome showed that the two cytologically unstable lines, which were also unstable in fertility and viability, are characterized by heteroplasmy at the mitochondrial 18S-5S locus (simultaneous presence of barley and wheat fragments). Stable lines 79(B) and 79(D) with normal fertility contained only wheat mitochondrial markers. It was assumed that the substantial instability of the nuclear genome in lines 79(C) and 79(A) was a result of nuclear-cytoplasmic incompatibility and was associated with heteroplasmy, while elimination or considerable reduction of barley material in the mitochondrial genome stabilized the nuclear genome of lines 79(B) and 79(D). In turn, the instability of the nuclear genome was responsible for a decrease in viability and fertility of plants.