Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : A joint genetic linkage mapping and genome-wide association study of drought and salinity tolerance and verticillium wilt and thrips resistance in cotton

Auteur : Abdelraheem, Abdelraheem R.T..

Etablissement de soutenance : New Mexico State University,

Grade : Doctor of Philosophy (PhD) 2017

Résumé partiel
Cotton (Gossypium spp.) is grown in arid and semi-arid regions including the southwest and west U.S., where abiotic and biotic stresses such as drought, salt, erticillium wilt (Verticillium dahliae) and thrips (Frankliniella occidentalis) are prevalent. Resistances or tolerances to these stresses are interconnected and have much in common ; however, the genetic basis of the resitances is not fully understood due to complexity of the stress resistance and difficulties in phenotyping. Although developing and using resistance germplasm is the most effective method to manange these stresses, most cotton cultivars and breeding lines have been developed under non-stress conditions. Therefore, genes for resistance to different stresses are randomly fixed in breeding lines that can be identified in breeding, genetic and genomic studies. The aims of this study were to measure the extent of genetic variation for the abiotic and bioticstress resistance in tetraploid cotton and to identify quantitative trait loci (QTL) responsible for drought and salt tolerance related morphological and physiological traits, and yield and its components as well as fiber quality under both stress and non-stress conditions, and for Verticillium wilt and thrips resistance.Two genomic approacheswith five independent studies were taken including genetic linkage mapping usingthree bi-parental permanent populations and a genome-wide association study (GWAS) using a diversity panel of 376 Upland cotton germplasm lines. In the first study, seedlings of 142 backcross inbred lines (BILs) derived from Upland cotton ‘Sure-Grow 747’ (G. hirsutum) * ‘Pima S-7’ (G. barbadense) were evaluated in two replicated tests for plant height, fresh shoot weight and root weight under two treatments [5% polyethylene glycol (PEG) and water-control conditions] using a hydroponic system in the greenhouse. The experiment in each test was a randomized complete block design with three replications. The analysis of variance for the two tests detected significant genotypic variation in PEG-induced stress tolerance within the BIL population and between the parents. Heritabilities were moderate to high and were higher under the control conditions than under the PEG treatment, and the three traits were also significantly and positively correlated. Based on a linkage map with 292 DNA markers, six QTL were detected including two for plant height, and two each for fresh shoot weight and root weight. This study represents the first report in using a permanent mapping population in genetic and linkage analysis of water stress tolerance in cotton

Présentation (PROQUEST)