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Document Type

Thesis - University Access Only

Award Date

1992

Degree Name

Master of Science (MS)

Department

Biology and Microbiology

First Advisor

Carl A. Westby

Abstract

Exposure to 'low non-freezing temperatures for an allotted period of time protects certain plants against freezing at another time. This process is referred to as hardening or cold acclimation. Winter barley phenotypes vary in their ability to survive lower temperatures. Freeze-resistant phenotypes survive better at lower temperatures than freeze susceptible phenotypes which are adapted to milder climates. Even though both resistant and susceptible types require cold acclimation or exposure to low non-freezing temperatures to achieve resistance, each type differs in the extent to which resistance is developed (60). The barley cultivar Dicktoo is an example of a more freeze resistant cultivar whereas Tennessee Winter is an example of a freeze susceptible barley cultivar. Research on cold acclimation (cold hardening) (38) has revealed a definite relationship between the presence or absence of certain soluble proteins and the low temperatures at which these plants survive and grow. It appears that cold acclimation induces a population of mRNAs-in barley plants that is different from the mRNA population present in non-acclimated barley plants (17). The mRNA population in turn is responsible for the protein population that is produced. The enzymes, ribonuclease I and ribonuclease II, are two proteins which have been identified with cold acclimation. In both acclimated and 2 non-acclimated barley plants, RNase I activity was found to be lower in plants that were more freeze resistant and higher in plants which were less freeze resistant (60, 61). Resistant cultivars were found to contain higher RNase II activity compared to susceptible cultivars ( 60). Messenger RNA can be used in reverse transcription to synthesize double-stranded cDNA which carries the same encoded information about a protein that a gene does. Furthermore, the cDNA of an organism or tissue can be ligated into a vector and cloned to establish a library. A different cDNA library can be obtained for each type of tissue used or for each. type of treatment applied to a common tissue. The objectives of this research were to: 1) determine the best way to isolate total RNA from non-acclimated Dicktoo barley tissue; 2) enrich for poly(A)*RNA using oligo(dT)-cellulose chromatography; 3) determine the conditions for producing clonable [sic] amounts of non- acclimated Dicktoo barley cDNA using Moloney-Murine Leukemia Virus Reverse Transcriptase (M-ML V RT); 4) generate a cDNA library enriched for mRNA species associated with non-acclimated, freeze resistant b&rley tissue (Dicktoo) using cDNA synthesized with M-MLV RT. The non-acclimated barley cDNA library that was obtained presumably carries clones responsible for RNase and other activities associated with the non-acclimated state. The cDNA library has been preserved and will be available for further studies.

Library of Congress Subject Headings

Barley -- Genetics
Barley -- Frost resistance
Messenger RNA
DNA -- Synthesis
Molecular cloning

Format

application/pdf

Publisher

South Dakota State University

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