Molecular characterization of water deficit stress inducible defensins from Atriplex canescens /
The mechanisms of gene regulation under water deficit stress were examined, focusing on a family of homologous genes from the woody desert shrub, Atriplex canescens. Plant tissue from A.canescens was chosen as a source of genes due to its ability to survive desiccation under severe stress levels. Di...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2000.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=731981441&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The mechanisms of gene regulation under water deficit stress were examined, focusing on a family of homologous genes from the woody desert shrub, Atriplex canescens. Plant tissue from A.canescens was chosen as a source of genes due to its ability to survive desiccation under severe stress levels. Differential hybridization screenings of cDNA libraries constructed from water deficit stress induced mRNA led to the isolation of several cross hybridizing cDNA clones. The cDNAs encode a small polypeptide whose sequence bears strong homology to antimicrobial proteins from several plant species called defensins. Based on sequence analysis, two genomic clones isolated from an A. canescens genomic library were partially characterized. The upstream regulatory regions of the two genomic clones include putative transcription factor binding sites such as abscisic acid response elements (ABREs) and additional regulatory motifs. The downstream regulatory regions include sequences representative of far upstream elements (FUEs) associated with mRNA stability and polyadenylation. The specific role of these putative 5' and 3' cis acting factors in gene regulation is discussed. Water deficit stress and ABA induced gene expression were examined. When the shortest full-length cDNA clone was used as a probe, the transcript was induced in roots, stems and leaves at stress levels ranging between water potentials of -0.9 to -2.8 MPa. Transcript lengths ranged between 0.5 to 0.780 kb, corresponding to minimum predicted sizes based on sequence analysis of cDNA clones. Transcripts were also induced by benchtop dehydration and exposure to ABA. RNaseH treatment and rapid amplification of 3' cDNA ends (3'RACE) indicated that differences in transcript lengths were due in part to the length of the poly(A) tail. |
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| Item Description: | Vita. "Major Subject: Plant Physiology". |
| Physical Description: | xii, 173 leaves : illustrations, map ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 136-170). |