|Fuchigami, Les - OREGON STATE UNIV|
|Yueju, Wang - OREGON STATE UNIV|
|NORELLI, JOHN (JAY)|
Submitted to: Abstract of International Horticultural Congress
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 2002
Publication Date: June 21, 2002
Citation: WISNIEWSKI, M.E., FUCHIGAMI, L., YUEJU, W., SRINIVASAN, C., NORELLI, J.L. OVEREXPRESSION OF A CYTOSOLIC ASCORBATE PEROXIDASE GENE IN APPLE IMPROVES RESISTANCE TO HEAT STRESS. ABSTRACT OF INTERNATIONAL HORTICULTURAL CONGRESS. 2002. Technical Abstract: During normal aerobic metabolism, molecular oxygen can undergo a series of univalent reductions to produce a variety of oxygen intermediates such as the superoxide radical. The presence of these reactive oxygen species (ROIs) can lead to peroxidation of cellular membranes and denatured proteins, and cause lesions in DNA. Various types of environmental extremes can result in a dramatic increase in oxidative stress. Plants have evolved an array of antioxidant enzymes (AO), such as ascorbate peroxidase (APX) and superoxided dismutase (SOD) to scavenge ROIs and detoxify them. In the present study, we have overexpressed a cytosolic APX gene, derived from spinach, in apple in order to determine if this improves resistance to environmental stress. 'Royal Gala' apple was transformed using Agrobacterium and the APX gene was placed under the control of a dual 35S promoter. At least twenty transgenic lines were identified using PCR. These lines were then rooted and placed in a growth chamber in preparation for field planting. Thus far, several lines have been demonstrated in laboratory tests to have improved resistance to heat stress. When leaf disks were placed at 44 degrees C for 14 h, disks from wild-type plants exhibited 100% electrolyte leakage, whereas transgenic lines exhibited 40% to 75% leakage, depending on the specific line. Further responses to cold, salt, and UV stress are in progress.