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also been infl uenced by unstable yields. On a world scale, wheat is attacked by
200–250 pathogens and pests, and may cause signifi cant economic losses in com-
mercial wheat production. Under weather conditions favourable to the pathogens,
yield losses in susceptible cultivars may be as great as 40–100 %.
It has become evident that the development of wheat genotypes for future agri-
culture and further crop improvement will require new genetic variation and the
selection of wheat cultivars that meet new challenges. Effi cient wheat breeding pro-
grammes will require breeding efforts, including
- New strategies in genebank research to exploit the genetic variation existing in
wild relatives. - The utilisation of the genetic variation in wild relatives to develop new germ-
plasm in pre-breeding programmes. - The introgression of new germplasm into the elite wheat pool.
3.4.1 Genebank Research
The role played in plant breeding by the wild and cultivated relatives of wheat and
by the old cultivars and populations stored in gene banks has greatly increased
recently. The effi ciency of research programmes in plant gene banks depends on the
accuracy and precision of evaluation techniques. The evaluation of large volumes of
germplasm using only traditional tools such as geographic origin, pedigree informa-
tion, botanical and agronomic descriptions is too time-consuming.
The establishment of a cost-effective core collection to represent the genetic
variability of the large germplasm collections traditionally available to breeders is
of vital interest. Core collections are useful for the association mapping of disease
resistance, seed quality and domestication-related traits. A good example is the core
collection of 372 accessions based on passport and simple sequence repeat (SSR)
marker data selected by Balfourier et al. ( 2007 ) in the Clermont-Ferrand Genetic
Resources Center to explore the diversity present in wheat accessions. Breseghello
and Sorrells ( 2006 ) also underlined the usefulness of association mapping when
breeders analyse traits with low heritability, such as yield components.
The use of wild relatives in traditional breeding is less effi cient when valuable
genes are linked with numerous unfavourable agronomic traits, in addition to which
these genotypes also have low yield potential. The transfer of useful genes is also
complicated by linkage drag , crossing barriers, the absence of pairing between
homoeologous chromosomes, etc. The effi ciency of gene bank research can be
improved through the joint application of new methods of genotyping and pheno-
typing, which enable plant breeders to
- Screen collections for genes important for breeding programmes.
- Identify unique alleles and characterise genetic resources at the gene level.
- Dissect the populations of wild relatives to provide insights into the allelic con-
tent of germplasm potentially useful for breeding.
Z. Bedő and L. Láng