88
is the doubled haploid technology used to produce homozygous progenies from the
F 1 generation in a single step. This technology is an excellent tool not only for cul-
tivar development, but also for pre-breeding and for the establishment of mapping
populations (Laurie and Bennett 1988 ). Another technology employed in larger
wheat research programmes is the use of in vitro cultures for somaclonal selection.
The use of molecular markers for the development of new germplasm and to
improve the effi ciency of pre-breeding is a great step forward in cereal breeding. It
enables breeders to accelerate the introgression and backcrossing of genes into
diverse genetic backgrounds, while allowing genes with similar phenotypic effects
to be pyramided. Marker-assisted backcross breeding (MABC) is a useful tool to
accelerate the introgression of genes into an adapted background. The simulation of
recombination during meiosis proves that breeders can recover the recurrent parent
using molecular markers more effi ciently than by traditional backcrossing (Frisch
et al. 2000 ). MABC provides effi cient positive foreground selection for the donor
trait, positive background selection for the recurrent parental genome and negative
background selection against undesirable donor parent alleles. Marker-assisted
selection (MAS) is a valuable technology for pyramiding genes for resistance to
diseases. The agronomic traits of BC 5 and BC 6 lines are very similar to those of the
recurrent parents. To exploit the advantages of new methods, pyramided gene com-
binations have been developed (Fig. 3.2 ), and a doubled haploid programme has
been set up in order to stabilize them in the frame of BIOEXPLOIT EU FP6 project
to improve durable leaf rust resistance of wheat (Vida et al. 2009 ).
In the framework of the HEALTHGRAIN FP6 EU project, a backcross pro-
gramme was carried out to introduce high amylose genes into current commercial
European cultivars using the triple SGP mutant lines developed by Lafi andra and his
team (Sestili et al. 2010 ) at the University of Tuscia, Italy. After three BC genera-
tions it was possible to select genotypes with amylose contents similar to that of the
mutant lines. The projected use of MABC to introgress transgenes into elite germ-
plasm will permit the rapid deployment of agronomic traits.
Selection for mutations induced using radiation or chemical agents was formerly
based on the detection of morphological traits or by phenotyping quality traits, an
approach not easily applied to a polyploid species such as wheat, as most mutations
Fig. 3.2 Pyramiding of Lr
genes using marker
assisted backcross and
doubled haploid
technology (Vida et al.
2009 )
Z. Bedő and L. Láng