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lines or the selection of a natural population representing
diversity for stress tolerance traits
3. The use of linkage mapping or association mapping
approaches to identify the quantitative trait loci (QTL) or
markers associated with stress tolerance-related param-
eters, such as leaf water retention, high rates of leaf pho-
tosynthesis, stomatal conductance, osmotic adjustment,
and faster canopy and root development.
4. The validation of the QTL or markers in a breeding
germplasm that have a different genetic background
5. The use of an appropriate MB approach such as MABC,
MARS or GWS to develop superior crop genotypes.
Genetic
engineering
approach
1. The identification of genes encoding signalling proteins,
TFs and effector proteins, and novel stress responsive
promoters controlling multiple stress tolerance
2. The identification of genes regulating stomatal opening
and closure and stress-induced expression to enhance
water use efficiency in crops
3. The genetic transformation and development of elite crop
genotypes with tolerance to high-temperature stress and
other environmental stresses
4. The assessment of promising transgenic lines for multiple
stress tolerance under field conditions
5. The deregulation of transgenic lines to enable the release
of a superior line or variety.
In this chapter, we are only emphasising different molecu-
lar breeding approaches and the role of these approaches for
enhancing stress tolerance in crops in a changing climate.
17. 3
Section I: Molecular markers and their
applications for crop improvement
Before starting the discussion on molecular markers, we should
be familiar with genetic markers. Genetic markers represent
genetic differences between individual organisms or species;
they do not represent the target genes themselves but act as
'signs' or 'flags'. Such markers themselves do not affect the
phenotype of the trait of interest because they are located near
or 'linked' to genes controlling the trait. The genetic markers
occupy specific genomic positions within chromosomes (like
