Analysis of a water-deficit stress induced gene (lp3) of loblolly pine (Pinus taeda L.) /
The lp3 gene, a water-deficit-stress (WDS) induced gene was proposed to be a nuclear-targeted protein involved in protection or transcription regulation. A high homology to ASRs (ABA, Stress and Ripening) was found in the C-terminal region of the putative LP3 protein while variable homologies were...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2001.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=728908201&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The lp3 gene, a water-deficit-stress (WDS) induced gene was proposed to be a nuclear-targeted protein involved in protection or transcription regulation. A high homology to ASRs (ABA, Stress and Ripening) was found in the C-terminal region of the putative LP3 protein while variable homologies were found in the N-terminal region (GenBank search). Transient expression of GUS activities, using gold particles coated with plasmid construct containing the CaMV35S promoter and an lp3-GUS in onion epidermis, slash pine suspension cells, and stably transformed tobacco seedlings, indicated that the LP3 protein would be targeted to the cell nucleus. Expression of GUS from the lp3-GUS construct was stronger with PEG and fluridone treatments than with ABA. The regulatory mechanism for stress response may differ from species to species, or the lp3 promoter may be triggered by similar substrates through the endogenous ABA synthesis pathway. GUS expression was not observed in transgenic tobacco plantlets containing lp3-GUS construct treated with gibberellin (GA₃), 2-methyl-4-dichlorophenoxy acetic acid (2,4-D), silver nitrate and ethphon (ethylene releasing agent) treatments. Germinated T-1 seeds containing the lp3 promoter-GUS construct showed expression of GUS activity up to 40 days during post-germination, then began to lose GUS activity after 40 days. When 5-azacytidine was included in the MS media, the T1 seedlings retained GUS activity. From this information, it was concluded that the loss of gene expression was associated with gene methylation. ExoIII-deletion analysis of the lp3-1 promoter fused with the uidA (GUS) gene as a reporter was carried out. Expression of GUS in transgenic tobacco showed that a promoter fragment of 1026 and 745 bp in length had strong responses to WDS, ABA and fluridone treatments. lp3 promoter fragment of 589 and 279 bp resulted in weaker expression, and a promoter fragment shorter than 115 bp had virtually no expression in all treatments. This study determined the location of the LP3 protein to be in the nucleus and the function of the LP3 protein is possibly a transcription factor or a DNA protectant. This study represents another step forward in the understanding of the WDS-response mechanisms involved in regulation and the function of lp3 in loblolly pine. |
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| Item Description: | Vita. "Major Subject: Plant Physiology". |
| Physical Description: | xii, 129 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 102-128). |