Classification and detection of Peronosclerospora species on the basis of DNA southern hybridization and the polymerase chain reaction /
| Main Author: | |
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1991.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | Four species were recognized among the 12 isolates of P. sorghi, P. sacchari, P. philippinensis, P. maydis, and P. sorghi Thailand strain on the basis of data from Southern blots of 76 probe and restriction enzyme combinations and from PCR amplifications of the ITS 2 and 5.8s rDNA. They are P. sorghi, P. sacchari, P. maydis and P. zeae. P. zeae is a new name suggested for P. sorghi Thailand strain, and P. sacchari includes both P. sacchari and P. philippinensis, which have been confirmed to be conspecific. The other two species maintain their identities. The phylogenetic relationships among these four species were inferred on the basis of comparison of 232 bands from Southern blots and PCR results by computer-assisted parsimony analysis using the PAUP program. The tree with the shortest length shows that P. zeae is closely related to P. maydis, and these two species are more related to P. sacchari, than to P. sorghi. Heterogeneity in the internal transcribed spacer 2 (ITS 2) of the rDNA repeated units was revealed. Except for one dominant fragment for each species, there are several less frequent fragments with different sizes, and each species has a unique banding pattern for ITS 2. The methylation of cytosine residues occurring in CCGG and GCGC sequences in the ribosomal genes of four Peronosclerospora species was examined on Southern blots of DNA fragments generated by digestion with isochizomer MspI and HpaII, and restriction enzyme CfoI. The blots were probed with a cloned ribosomal gene of Neurospora crassa, as well as an 1.3 kb PCR amplified fragment of 5.8s rDNA and ITS 2 of P. sorghi, but no methylation was found. A species specific probe was developed for P. sorghi, and species-specific PCR primers for P. sorghi and genus-specific primers for Peronosclerospora were also successfully designed. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Plant Pathology." |
| Physical Description: | x, 71 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |