Warpeha, K. M. , Carol, A. , Gibbons, J. T. , Tree, R. , Slusser, J. , Kaufman, L. S. .
Phenylalanine is critical to protection from UV radiation in Arabidopsis and soybean.
Environmental assessments over the last ten years indicate incident UV radiation is increasing. It is widely agreed that UV-B (290-320nm) radiation causes damage to crop plants worldwide, reduces quality of seed protein, overall plant biomass and photosynthetic capacity, alters species competition, plant ultrastructure, and pigment production, and increases susceptibility to disease. Etiolated insertion mutants of the prephenate dehydratase (PD1) gene of Arabidopsis lack the ability to synthesize phenylalanine and subsequent downstream products in response to blue light or UV radiation. Low doses of high energy UV (254 nm) is lethal to etiolated pd1 mutants, but not to etiolated wt or mutants of the other members of the PD family. The plastids of pd1 mutants in developing leaves are less mature (proplastids) compared to wt (etioplasts). The cotyledons of dark-grown pd1 mutants have less cuticular surface wax, and fewer long chain fatty acids, particularly at the tip of the cotyledon. An identical or analogous system of blue light-induced phenylalanine production may exist in soybean. Long-term growth after UV irradiation indicates 3:1 ratio of survival vs. mortality for etiolated seedlings treated with 300 or 317 nm. Seedlings treated with 300 nm develop fewer hairs on the primary leaf, TEM reveals that 300 nm UV results in complete destruction of internal organelles, loss of osmotic regulation and the loss of cell wall integrity. Deconvoluting microscopy reveals evidence of phenylalanine-derived pigments collecting in the hairs of seedlings irradiated at 332 nm and 368 nm, but not 300-325nm. The cross feeding of exogenous phenylalanine can prevent UV damage or death in both Arabidopsis and soybean.
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1 - University of Illinois at Chicago, Biological Sciences, 900 S. Ashland Ave, m/c 567, rm 4268, Chicago, IL, 60607, USA
2 - University of Illinois at Chicago, Biological Sciences
3 - Colorado State University, UV-B Monitoring Project
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM