Genetic study of resistance to charcoal rot and Fusarium stalk rot diseases of sorghum

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Show simple item record Adeyanju, Adedayo en_US 2014-04-25T15:27:31Z 2014-04-25T15:27:31Z 2014-04-25
dc.description.abstract Fusarium stalk rot and charcoal rot caused by Fusarium thapsinum and Macrophomina phaseolina respectively are devastating global diseases in sorghum that lead to severe quality and yield loss each year. In this study, three sets of interrelated experiments were conducted that will potentially lead to the development of resistance based control option to these diseases. The first experiment was aimed at identifying sources of resistance to infection by M. phaseolina and F. thapsinum in a diverse panel of 300 sorghum genotypes. The genotypes were evaluated in three environments following artificial inoculation. Out of a total of 300 genotypes evaluated, 95 genotypes were found to have resistance to M. phaseolina and 77 to F. thapsinum of which 53 genotypes were resistant to both pathogens. In the second experiment, a set of 79,132 single nucleotide polymorphisms (SNPs) markers were used in an association study to identify genomic regions underlying stalk rot resistance using a multi-locus mixed model association mapping approach. We identified 14 loci associated with stalk rot and a set of candidate genes that appear to be involved in connected functions controlling plant defense response to stalk rot resistance. The associated SNPs accounted for 19-30% of phenotypic variation observed within and across environments. An analysis of associated allele frequencies within the major sorghum subpopulations revealed enrichment for resistant alleles in the durra and caudatum subpopulations compared with other subpopulations. The findings suggest a complicated molecular mechanism of resistance to stalk rots. The objective of the third experiment was to determine the functional relationship between stay-green trait, leaf dhurrin and soluble sugar levels and resistance to stalk rot diseases. Fourteen genotypic groups derived from a Tx642 × Tx7000 RIL population carrying combinations of stay-green quantitative trait loci were evaluated under three environments in four replications. The stg QTL had variable effects on stalk rot disease. Genotypes carrying stg1, stg3, stg1,3 and stg1,2,3,4 expressed good levels of resistance to M. phaseolina but the combination of stg1 and stg3 was required to express the same level of resistance to F. thapsinum. Other stg QTL blocks such as stg2 and stg4 did not have any impact on stalk rot resistance caused by both pathogens. There were no significant correlations between leaf dhurrin, soluble sugar concentration, and resistance to any of the pathogens. en_US
dc.description.sponsorship Center for sorghum improvement en_US
dc.language.iso en en_US
dc.publisher Kansas State University en
dc.subject Sorghum en_US
dc.subject Fusarium thapsinum en_US
dc.subject Macrophomina phaseolina en_US
dc.subject Stalk rot en_US
dc.subject Stay-green en_US
dc.subject Association mapping en_US
dc.title Genetic study of resistance to charcoal rot and Fusarium stalk rot diseases of sorghum en_US
dc.type Dissertation en_US Doctor of Philosophy en_US
dc.description.level Doctoral en_US
dc.description.department Department of Agronomy en_US
dc.description.advisor Tesfaye Tesso en_US
dc.subject.umi Agronomy (0285) en_US
dc.subject.umi Bioinformatics (0715) en_US
dc.subject.umi Pathology (0571) en_US 2014 en_US May en_US

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