Segregating F 4 families from the cross between drought sensitive (Yecora Rojo) and drought tolerant (Pavon 76) genotypes were made to identify SSR markers linked to leaf chlorophyll content, flag leaf senescence and cell membrane stability traits in wheat (Triticum aestivum L.) under water-stressed condition and to map quantitative trait locus (QTL) for the three physiological traits. The parents and 150 F 4 families were evaluated phenotypically for drought tolerance using two irrigation treatments (2500 and 7500 m 3 /ha). Using 400 SSR primers tested for polymorphism in testing parental and F 4 families genotypes, the results revealed that QTL for leaf chlorophyll content, flag leaf senescence and cell membrane stability traits were associated with 12, 5 and 12 SSR markers, respectively and explained phenotypic variation ranged from 6 to 42%. The SSR markers for physiological traits had genetic distances ranged from 12.5 to 25.5 cM. These SSR markers can be further used in breeding programs for drought tolerance in wheat.
Stress induced by high temperature represents a major constraint over wheat
production in many production areas. Here, the comprehensive coverage of the
wheat genome achievable using single nucleotide polymorphism markers was
exploited to carry out a genetic analysis targeting yield components in
plants exposed to high temperature stress. The mapping population was a set
of doubled haploid lines derived from a cross between the cultivars Yecora
Rojo and Ksu106. Both of the parental cultivars and their derived population
were tested in the field in two locations over two consecutive seasons; at
each site, two sowing dates were included, with the later sowing intended to
ensure that the plants were exposed to high temperature stress during the
grain filling period. Composite interval mapping detected 93 quantitative
trait loci influencing grain yield and some related traits, along with 20
loci associated with a ?heat susceptibility index? (HSI). The loci were
distributed over all 21 of the wheat chromosomes. Some of these loci were of
large enough effect to be considered as candidates for the marker-assisted
breeding of high temperature tolerance in wheat.
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