Type of Document Master's Thesis Author Youlin, Tang M.S. Author's Email Address email@example.com URN etd-42398-124213 Title Response of Leaf Protein to Ozone in Two White Clover Clones Degree Master of Science Department Plant Pathology, Physiology, and Weed Science Advisory Committee
Advisor Name Title Chevone, Boris I. Committee Chair Chevone, Boris I. Committee Member Hess, John L. Committee Member Moore, Laurence D. Committee Member Keywords
- White Clover
- Ozone-Responsive Protein
Date of Defense 1998-05-07 Availability restricted AbstractResponse of Leaf Protein to Ozone in White Clover Clones
A white clover ( Trifolium repens ) system, based on one
ozone-sensitive (NC-S) and one ozone-resistant (NC-R) clone,
has been developed as an indicator to estimate the effects
of tropospheric ozone on plant biomass production. A
reduction in the vegetative biomass ratio (NC-S/NC-R) of the
clones was correlated with increasing concentrations of ozone
during a 28-day exposure period. However, the mechanism of
ozone sensitivity or tolerance at the biochemical or
molecular level is not known. Superoxide dismutase isozyme
activities in the two clones did not respond differently to
ozone treatment. However, catalase activity increased
somewhat more in the leaf tissue of NC-R, compared to NC-S,
after ozone treatment. Two-dimensional polyacrylamide gel
electrophoresis (PAGE) showed the presence of two proteins
(Ozone-Response-Proteins, ORPs) that were more responsive to
ozone in the tolerant genotype than in the sensitive one.
After ozone treatment for three days, the ORPs were four-fold
higher in leaf tissue of NC-R compared to NC-S. Also,
the amount of the ORPs was twenty-fold higher in leaf tissue
of ozone-treated NC-R than in that of control NC-R. These
proteins have apparent molecular weights of 21.5 kD and
23 kD and isoelectric points of 4.1-4.4 on SDS-PAGE gels.
The filtrate of a 100 kD concentrator showed that the native
molecular weights of the ORPs were less than 100 kD.
The results obtained from a study of field samples
demonstrated that protein content in leaf tissue of both
NC-R and NC-S was positively correlated with ORP content.
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