Seed desiccation and germination have great potential for oxidative stress. Glutathione, one of the most abundant antioxidants in plant cells, is a crucial to the plant's defense mechanisms. To better understand glutathione's responses during these two stages, we examined its dynamics in wildtype Arabidopsis seeds and in a transgenic line containing an antisense glutathione reductase2 (anGR2) cDNA insert. Seeds from the two genotypes were compared morphologically. Glutathione levels in maturing and germinating seeds were measured by HPLC, and GR activity by native PAGE. Cytosolic glutathione was measured in situ by confocal laser scanning microscopy. Stress in the form of natural and accelerated ageing, and germination at high and low temperature and at low water potential was applied to both WT and anGR2 seeds to test vigor. Results show similar glutathione levels and GR activity (except during late imbibition) in WT and anGR2. In both genotypes, GSH/GSSG ratio increased and GR activity decreased during seed maturation. During imbibition, the glutathione pool becomes very reduced (<1% GSSG) and in WT seeds, GSH levels increase mostly by GSSG recycling. Cytosolic GSH in embryonic epidermal cells was estimated to be 1.1-1.6 mM. AnGR2 seeds aged faster, and were less tolerant of heat and drought stress than WT. Accumulation of glutathione during maturation indicated that glutathione is a major antioxidant in the seed during storage. Changes in GSH levels during imbibition coincided with ROS production during radicle protrusion. Under stress conditions, anGR2 seeds showed lower vigor, indicating perturbations in the ROS scavenging systems particularly GR2. / Master of Science

published_or_final_version / Botany / Doctoral / Doctor of Philosophy

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4 pp. / Originally published: 2002 / This is a list of sources for seed and plants for the Upland Southwest. Various sources for bulbs,wildflowers, grasses and reclamation seeds, vegetable seeds, fruits and nuts, trees and plants are listed.

4 pp. / How to transplant a cactus (az1376) Problems and pests of aloes,agaves,cacti and yuccas (az1399) Cactus, Agave,Yucca,and Ocotillo (az1225) / Propagation of agaves and cacti from seed and cuttings is an easy-to-accomplish process. Cuttings and seed sown during the appropriate time of year using the methods discussed will produce numerous progeny.

3 pp. / Due to worldwide shortages of non-dormant alfalfa seed, production opportunities and acreage have increased recently in Central Arizona. Seed production for profitability is challenging. Cultural practices differ from those commonly used in forage production. This article outlines management recommendations that may help to accomplish profitable seed alfalfa yields.

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