The next round of backcrossing
(BC3) will bring the abaca content to 93.7%, by which time it is almost completely like abaca.
Therefore, the objective in this study was to introgress the blast resistance gene into local Malaysian variety, MR264 by applying marker-assisted backcrossing
breeding program and thereby enhancing the background selection.
Frequency of favourable allele for background QTLs under different population sizes : MBLUP was background selection method, the figure 5 show that during backcross phase, the difference of frequency of favourable allele for background QTLs is a little between two population sizes, backcrossing
three generations, under two different population sizes: 500 and 1000, frequencies of favourable allele for the first background QTL were 0.9858 and 0.9912, and they were 0.9868 and 0.9876 for the second background QTL, backcrossing
five generations, under two population sizes, frequencies of favourable allele for two background QTLs both reached 1.
The other methods (Figure 1A to F) did not correctly reproduce the clustering, and the RC1b generation was not clustered together with the other backcrossing
generations with its respective recurring parent.
F1 hybrids and F2 backcross hybrids were raised and used as parental broodstock in 2 cycles of backcrossing
Marker-assisted selection was employed for each backcross to identify B[C.sub.n][F.sub.1] plants with the SAP6 and SU91 markers for subsequent backcrossing
with the susceptible dark red kidney parents.
If resistance or host-recognition genes are dominant in hybrids, then backcrossing
could lead to a variety of results [ILLUSTRATION FOR FIGURES 1C, D OMITTED].
At the other extreme, hybrid zones composed of just sterile [F.sub.1] hybrids should accumulate the fewest taxa because the complete lack of backcrossing
prevents the continuum of intermediates from being formed that would facilitate host shifting.
hexagona fruits could only be produced from crosses between the species (producing [F.sub.1] seeds) or from backcrossing
with [F.sub.1] individuals.
The genetic stocks were developed by crossing the recurrent parents Atlas, Kansas Collier, Rox Orange, and Early Hegari-Sart to brown midrib sources N121 (bmr-6) and F220 (bmr-12, donated to our project by the late Robert Kalton), followed by a minimum of four cycles of selfing and backcrossing
. Crossing was facilitated by the use of the nuclear male-sterility gene [ms.sub.3].
Specifically, our models give the conditional probability distributions for the number of markers indicating mixed ancestory as a function of the number of markers examined for various backcross categories under a scenario of unidirectional backcrossing
. For example, our models give the probability that a backcross 1 individual will be confused as a pure species (or as an F1) as a function of the number of markers examined; the models do not give the probability that an individual is a backcross 1 given its complement of markers.
By repeatedly backcrossing
the hybrid of these species to HS while selecting for feeding (i.e., larval survival and weight gain) on soybean, we moved loci conferring the ability to feed on soybean from HV, into the genetic background of the specialist, HS.