Influence de la recombinaison sur la variabilité génétique. II. Étude par simulations

Abstract

complement an experimental study of the possible interest for plant breeders of an allele increasing recombination rates. In the first simulation study, 4 populations of 10 individuals were simulated in the case of high (45%), medium (19.6%) and low (6.9%) recombination frequencies. Ten-plant populations were derived by one generation, either from selfing or from crossing in a circular mating design, from each of the 4 populations. For each initial population, the distribution of the genetic variances in the populations obtained by one mating system overlapped widely in the 3 cases of recombination rates considered, whether the initial population presented an excess of coupling phase, or an excess of repulsion phase. An experimental assessment of the effect of recombination rate differences on genetic variability of quantitative traits is therefore likely to be difficult. The second study simulated a recurrent selection program in the case of high (45%), medium (19.6%) and low (9%) recombination rates. The mean genetic value increased somewhat more slowly and reached a slightly lower value for low recombination rates, whereas the genetic variance remained the highest after the second selection cycle. The evolutions in genetic mean values and genetic variances were almost identical for medium and high recombination frequencies. Thus, an allele which increases recombination rates will only be of interest in the case of close linkage or difficult crossing. Otherwise, a circular

The roots of future rice harvests

“…Since breeding is a numbers game, this would require populations that are too large. Theory demonstrated that a two or more step procedure is much more efficient although slightly slower (Kervella et al [ 1993 ]). Recurrent selection with a male sterility gene to facilitate intercrossing will be a way to go (Grenier et al unpublished work).…”

Influence de la recombinaison sur la variabilité génétique. I. Étude expérimentale

“…Dans cette expérience, le gène Rm1 qui accroît les taux de recombinaison dans la plupart des segments testés, excepté le segment sur le chromosome IV délimité par les gènes B1 et An6 (Farcy et al, 1986;Cornu et al, 1989;Robert et al, 1991) (Miller et Rawling, 1967;Mather et Jinks, 1971;Gallais, 1974, Snape, 1976Snape et Simpson, 1981 (Kervella et al, 1993).…”