Transmission rates of extra chromosomes in alien monosomic addition lines of Japanese bunching onion with extra chromosomes from shallot

In a series of alien monosomic addition lines (AMALs, FF+nA, 2n=17) of Alli um fistulosum L. with extra chromosomes from A. cepa L. Aggregatum group, t he transmission rates of the extra chromosomes were assessed to examine the possibility of maintaining these lines by seed propagation. Chromosome num bers of the seedlings obtained from reciprocal crossings between the AMALs and A. fistulosum (2n=16; genomes, FF) were 16 and 17. The percentage of pl ants with 17 chromosomes in the seedlings obtained from the crossings FF(fe male) X FF+nA (male) and FF+nA(female) x FF (male) were used to indicate th e male and female transmission rates, respectively. The male transmission r ates varied from 0 to 7.6 % (mean 2.6 %) among eight kinds of extra chromos omes, whereas the female transmission rates ranged from 6.1 to 40.4 % (mean 19.8 %). These results revealed the following: 1) Both the male and female transmission rates are generally low. 2) These rates show considerable var iations among the extra chromosomes. 3) The female transmission rate is obv iously higher than the male transmission rate in all AMALs. Furthermore, bo th transmission rates of the extra chromosome 8A were relatively high and t hose of 5A were low. Chromosome numbers of the pollen grains produced by th e AMALs were eight and nine. The percentages of pollen grains with nine chr omosomes varied from 18.1 to 49.4 % (mean 34.9 %) among the eight types of AMALs and were undoubtedly higher than the male transmission rates in all t he AMALs. These phenomena seem to relate to a certation between pollen grai ns with different chromosome numbers or a chromosome elimination after fert ilization. The present results demonstrate that crossings, with the AMALs a s seed parents, are useful to maintain the series of AMALs by seed propagat ion.