Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/10/2006
Publication Date: 1/28/2009
Citation: Mahan, J.R., Gitz, D.C., Payton, P.R., Allen, R. 2009. Overexpression of glutathione reductase in cotton does not alter emergence rates under temperature stress. Crop Science. 49(1):272-280. Interpretive Summary: Low and high temperatures at planting are known to have negative effects on seedling growth and development. One source of negative effects on seedlings is related to damage associated with oxidative compounds produced in response to low and high temperatures. Cotton, like most plants, has naturally occurring protective systems however the ability of these systems to protect the plant may not be sufficient. In this study one component of the protective system, the enzyme glutathione reductase was increased transgenically. The enzyme was increased 8-fold and the performance of the altered cotton was monitored under thermal stress. It was found that the increased enzyme activity did not improve performance of the seedling which suggests that this may not be an effective approach for plant improvement.
Technical Abstract: The interval between planting and seedling emergence is affected by soil temperature. Low and high temperature limitations on seedling emergence are important considerations in determining when to plant. Cotton on the Southern High Plains is particularly affected by temperature stress. Oxidative damage is thought to be involved in delays in emergence under unfavorable temperatures. In this study the activity of the antioxidant enzyme glutathione reductase was transgenically increased 8-fold in cotton in an effort to reduce emergence times under thermal stress. In addition to the transgenic glutathione reductase cotton, five other cotton lines were included for comparative purposes. Emergence times under thermal variation in the field at four planting dates and under constant exposure to a gradient of temperature in the laboratory were not appreciably affected by enhanced glutathione activity. Oxidative damage assessed in terms of malondialdehyde levels was not appreciably decreased by enhancement of glutathione reductase activity. Based on these results it is suggested that enhancement of glutathione reductase activity in cotton seedlings does not reduce thermally related oxidative limitations on seedling emergence.