Genetic analysis of drought stress response in Arabidopsis thaliana and Brassica rapa
2013
El-Soda, M.
Drought is the major abiotic stress affecting plant growth and limiting crop productivity worldwide. Plants have evolved three adaptive strategies, drought escape, drought avoidance and drought tolerance, to cope with drought. Knowledge on how Quantitative Trait Loci (QTL), or genes underlying these strategies interact with their environments will significantly increase our understanding and the success of breeding for drought tolerance. This thesis focused on phenotyping shoot and root traits ofA. thaliana and B. rapa grown on sand and in greenhouses,to further understand how plants can adapt to natural drought stress. In chapter 2, an already existing ArabidopsisRIL population was selected based on the differential root drought response of the two parental lines, Sha and Col, to be evaluated under different water regimes. Chapter 3 illustrated the use of GWAS in identifying candidate genes that are associated with pant response to drought.. In order to apply the same methodology in crop breeding, chapter 4 introduces a contribution to the genetic mapping of a new B. rapa RIL population, consisting of 160 lines and genotyped with 270 different markers was achieved. The morphological and physiological responses of this population to drought was evaluated in chapter 5. The results presented in the present thesis demonstrate that QxE is an important component of the genetic variance and can play a great role in improving drought tolerance in future breeding programs. In general, several QTL and SNPs were mapped either with main effect or with interaction with environments QxE. Many of the mapped QTL showed conditional neutrality and antagonestic pleiotropy.
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