Infection of sorghum seedlings by Sporisorium reilianum (Kuhn) Clinton (Langdon and Fullerton), and molecular markers for head smut resistance mechanisms /
A series of trials were done to determine germination of
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1996.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739669061&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | A series of trials were done to determine germination of teliospores of Sporisorium reilianum on artificial media or near sorghum seedling tissues. Germination was detected as early as 18 hours on culture media and reached levels in the range of 8-28 % within 48 hours. These values were never achieved in the presence of seedlings, where teliospores germinated slower and at lower levels (2.5 to 13%). Elongated germ tubes arising from the germinating teliospore were eventually found on epicotyl tissues, while promycelia and sporidia were the only structures found on culture media. An inoculation technique was developed in which seed imbibed for 18 hours were planted in holes at a depth of 5 cm and covered with a soil:tcliospore mixture (50: 1). Infection levels in susceptible sorghum lines (RTx7O78, B1 and SC241- 12E) ranged from 40 to 92%, suggesting that this infection assay is superior in efficiency compared to other methods and mimics natural infection. Two different head smut resistance mechanisms described for sorghum were studied in field and greenhouse experiments using two different segregating populations. Phenotypic ratios in F3 generations suggested monogenic control for both mechanisms but with different dominance relationships. Resistance of the meristematic type appeared to be recessive in the head smut resistant lines CS3541 and BTx635. Bulked segregant analysis for head smut reaction phenotypes after sporidial inoculation permitted tagging the meristematic resistance locus (hsr) with RAPD and AFLP markers spanning a region of approximately 37 cM. Two AFLP markers were identified that flank the hsr locus at 2.6 and 2.9 cM. Phenotypic ratios in the F3 generation from the cross BTx635 x B1 exposed to natural infection at Corpus Christi, suggested that non-meristematic resistance is controlled by a dominant locus. Use of field data to deduce the genotype in the F2 generation for head smut reaction and to pool F3 families for bulked segregant analysis of the non- meristematic resistance locus, suggested that disease escape is a major confounding factor of head smut phenotype. Resistant and susceptible bulks of F3 families were surveyed for polymorphisms by AFLP analysis. The co-segregation of smut phenotypes of 57 F3s with one AFLP suggested loose linkage of the marker to the HSR1 locus. |
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| Item Description: | Vita. "Major Subject: Plant Pathology". |
| Physical Description: | x, 86 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 71-75. |