The population genetics of Sporisorium reilianum, the head smut pathogen of sorghum and maize /
Genetic diversity in the head smut pathogen rsity Microfilm Inc. Sporisorium reilianum was assessed using anonymous ALP loci in the genomic DNA of isolates sampled from two different hosts in several regions of the world. Southern hybridizations to 473 anonymous random probes detected a high level o...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1998.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=733059461&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Genetic diversity in the head smut pathogen rsity Microfilm Inc. Sporisorium reilianum was assessed using anonymous ALP loci in the genomic DNA of isolates sampled from two different hosts in several regions of the world. Southern hybridizations to 473 anonymous random probes detected a high level of variation when S. reilianum collected from sorghum (SHS) were compared to S. reilianum isolates from size (MHS). Fifty-five percent of the prob-enzyme combinations were polymorphic. However, when the comparisons were done within each host, a significantly lower genetic diversity was found among 10 SHS isolates and among 10 MI-IS isolates. Only 8 and 3% of the prob-enzyme combinations were polymorphic respectively. Eleven and four suitable polymorphic loci that differentiate isolates within SHS and MI-IS were selected. Ten single-locus probes that identify faxed polymorphisms between both smuts also were selected. The limited genetic diversity within hosts and the high divergence between hosts suggests that these two smuts have evolved independently from a source population and strong selection for strict host specialization has maintained their distinct lineages. The genetic structure of nine field populations of SHS was analyzed using the polymorphic probes selected previously. Nine restriction fragment length polymorphisms IRFLPSI were assayed in 459 isolates of S. reilianum collected from different regions of Mexico, Niger and the USA. Low levels of gene diversity were detected in the nine populations. Only two alleles were present for each RFLP locus. The seven populations from the Western Hemisphere The other allele was more frequent for most of the loci in the African populations. There was a significant excess of homozygotes in all of the populations studied. Genotypic diversity was moderately high across the nine populations. On average 12 multilocus genotypes IMLGTSI were found in a sample of 51 isolates from each population. In total 54 MLGTS were identified. The two African populations had 28 MLGTS that were not present in the Mexican and US populations. There was little evidence for gene flow between Africa and the Americas, although there was evidence for geneflow among the Texan and Mexican populations. The low gene diversity and the high homozygosity found in these populations support the hypothesis that sister sporidia frequently integrate during the sexual cycle in field populations, leading to high levels of inbreeding. |
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| Item Description: | Vita. "Major Subject: Plant Pathology". |
| Physical Description: | xii, 90 leaves : illustrations ; 28 cm. |
| Bibliography: | Includes bibliographical references (leaves 66-72). |