Characterization of an anther specific anionic peroxidase and the effects of gibberellic acid on the peroxidase activity in Brassica rapa

Day, Charles

Characterization of an anther specific anionic peroxidase and the effects of gibberellic acid on the peroxidase activity in Brassica rapa

Persistent URL

http://hdl.handle.net/10456/15665

Author(s)

Day, Charles

Date Issued

May 2, 2011

Abstract

A protein complex displaying anionic peroxidase activity has been discovered in unopened flower buds of Brassica rapa. Previous experiments determined the anionic peroxidase activity to be found only within the stamen of unopened flower buds and this activity to be absent in the ms2 sterile line and have partial activity in the ms1 mutants. In this study, experiments were performed to further investigate peroxidase activity patterns, to determine if GA3 treatments can influence this activity pattern and if GA3 treatments recover the anther specific anionic peroxidase (AS-AnPOX) in ms1 and ms2 cytoplasmic male sterile mutants. Native gel electrophoresis showed an increase in the peroxidase activity (isoelectric point of 3.5) 8 days after planting and activity decreases each progressing day until the flower bud is opened. AS-AnPOX activity was found to be absent in the ms2 mutants and partially present in the ms1 sterile line. GA3 treatments were performed on wildtype and cytoplasmic male sterile mutants, and showed an acceleration in the appearance of AS-AnPOX activity in wildtype B. rapa and no effect on AS-AnPOX activity in either CMS line. This study confirmed an activity timeline of the AS-AnPOX as well as reaffirmed the absence of this activity in ms1 and ms2. This study also showed that small concentrations of GA3, when applied to the developing flower buds of wildtype plants, accelerated AS-AnPOX activity, but this concentration of GA3 could not reverse the absence in activity seen in the CMS plants. The cytoplasmic male sterility may be attributed partially to the absence of the AS-AnPOX which may lead to abnormalities such as premature programmed cell death of the tapetum and the improper maturation of the pollen grains.

First Reader(s)

Kleinschmidt, Ann