Yong Zhang

Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

Plant Science

First Advisor

D.G. Kenefick


Expression of cold-regulated genes is essential for development of freeze resistance, enabling improved stand survival of plants after freeze stress. An objective of iii this study were to determine whether homologs of barley cold-regulated genes HVCR8 and HVCR21 are expressed in wheat (TACRB and TACR21) and, if so, how they respond to temperature change. Northern hybridization analysis was used to investigate the expression and characterization of TACR8 and TACR21 in a freeze resistant (FR) and freeze susceptible (FS) wheat cultivar utilizing the barley cDNA clones pUD8 and pGD21. Results from in vitro transcription demonstrated that the anti-sense strand of pUD8 was produced with the T7 promoter whereas this strand in pGD21 was revealed by the SP6 promoter. Results of Northern hybridization analysis indicated TACR8 and TACR21 were expressed in wheat and were up-regulated as early as 1 week by cold (2°C). The rate of mRNA accumulation for the two cDNAs in the FR cultivar in response to 2°C was different from that observed in the FS cultivar over the 4-week cold period. Transcript levels of TACR8 and TACR21 were higher in the FS compared to the FR cultivar after one week of 2°C treatment, and were maintained at a higher expression level in FS plants through the fourth week. When plants were transferred to 25°C after 2°C exposure, transcript levels of TACR8 and TACR21 rapidly declined. Decrease of mRNA accumulation for both genes was slower in FR plants when transferred to 25°C after 4 weeks at 2°c than in FS plants. Transcripts of TACR8 and TACR21 disappeared within about 6 hours at 25°C in both FR and FS plants. Different responses of TACR8 and TACR21 to 2°C and reversal of these responses from 25°C exposure by the FR compared to the FS cultivar indicate these genes follow an expression pattern similar to the time requirement for the induction and loss of freeze resistance in wheat, suggesting they might be involved in this important process.

Library of Congress Subject Headings

Wheat -- Effect of temperature on
Wheat -- Frost resistance
Wheat -- Genetics




South Dakota State University



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