UNUSUAL INHERITANCE OF THE MITOCHONDRIAL GENOME ORGANIZATION IN THE PROGENY OF RECIPROCAL CROSSES BETWEEN ALLOPLASMIC HEXAPLOID WHEAT REGENERANTS

The transmission of a structurally-hypervariable fraction of the mitoc hondrial genome has been studied in 42 F-1 progenies obtained from rec iprocal crosses between self-pollinated alloplasmic wheat plants regen erated after long-term somatic embryogenesis. This fraction of the gen ome is maternally and stoichiometrically inherited. In contrast, some additional restriction fragments specific to regenerated plants displa y a more complex mode of sexual transmission: one of the additional fr agments was stoichiometrically and systematically inherited whereas tw o others were detected only in certain F-1 hybrids. Assuming that the detection, by Southern analysis, of such a fragment in regenerated pla nts is due to the amplification of a pre-existing substoichiometric mo lecule generated by the activation of a rare recombination event, our results suggest that the probability of detecting a novel fragment in the F-1 hybrids could be determined by the length of the repeated sequ ence at which recombination occurs.