Document Type
Dissertation - University Access Only
Award Date
1995
Degree Name
Doctor of Philosophy (PhD)
Department / School
Biology and Microbiology
Abstract
An analysis of molecular forms of ribonuclease in barley was undertaken to determine if differential expression of this enzyme existed in a freeze resistant V (FR)1 or a susceptible (FS) cultivar. The hypothesis for this research was that genes (and accompanying RNA metabolism) important for plant stand survival after freeze stress (freeze resistance, a polygenic trait) are concentrated in FR cultivars as a result of natural freeze selection, and that the accompanying RNases in FR and FS plants can be differentiated. Cultivars used for analysis were chosen based on records of field stand survival to freeze stress. Objectives compared FR and FS plants by: showing freeze selection influences RNase species, such species can be isolated, and their activity changed by plant exposure to 2 ° c. Purification of RNase was from 6 d seedlings, and also after exposure to 2 ° c up to 4 wk. A 5- step procedure was used ending with Concanavalin A (Con A), not retaining the non-glycosylated (RNase I type) but retaining the glycosylated (RNase II) enzyme. Further 1See page vii vi separation was by SOS-PAGE containing RNA, allowing positive enzyme identification by RNase activity. A version of 2- dimensional electrophoresis was also used, applying the above SOS-PAGE with RNA in the second dimension. Results with RNase I fraction showed freeze selection repressed activity of one RNase species similar to that in the commercial FR cultivar; this species was estimated to be 26 kD with a pH optima of 6.5; activity was repressed by treating plants at 2 ° c; and activity of a second species (18 kD) with a pH optima of 5.5 was enhanced by 2 ° c. The 26 kD RNase was further resolved into at least seven activity zones, and the 18 kD into four by 2-D electrophoresis. A primary effect of plant exposure to 2 ° c was more of both the 18 and 26 kD RNase in the Con A retained fraction, suggesting glycosylation was enhanced by this plant treatment.
Library of Congress Subject Headings
Barley - Frost resistance
Barley - Genetics
Ribonucleases
Format
application/pdf
Number of Pages
115
Publisher
South Dakota State University
Recommended Citation
Ding, Xiang, "Cultivar and Temperature Altered RNase Species in Winter Barley" (1995). Electronic Theses and Dissertations. 1173.
https://openprairie.sdstate.edu/etd2/1173