Widhalm, Joshua R. , Stone, Julie M. , Paparozzi, Ellen .
Nitrogen deficiency-induced senescent A. thaliana rosette leaves accumulate defense-related proteins.
Leaf senescence is an intricately regulated event in which cells transition from nutrient assimilation to nutrient remobilization. Leaf senescence is the final step in leaf development but may be prematurely induced by an environmental stress such as nitrogen (N) deprivation. A. thaliana plants were hydroponically grown under short days to promote vegetative growth and delay flowering with sufficient amounts of all macro- and micro-nutrients in conjunction with the appropriate N treatment. Plants were supplied 120 ppm N as nitrate for eight weeks followed by 0 ppm N for three weeks to induce leaf senescence. Senescing rosette leaves were characterized by anthocyanin accumulation in the midrib and the underside of the leaf. Plants were then allowed to either re-green with restoration of 120 ppm N or remain N-deprived by continued treatment with 0 ppm N. Nitrogen deficiency-induced leaf senescence symptoms were diminished in re-greened plants after three weeks of N reapplication. Symptoms progressed to the death of lower rosette leaves and stunted growth of upper rosette leaves in plants continually deprived of N. Analysis by two-dimensional (2D) gel electrophoresis showed accumulation of two ~60 kD proteins with pIís of 6.4 and 6.7 in N deficiency-induced senescent leaves and attenuation of the protein levels in re-greened leaves. Tandem mass spectrometry (MS/MS) indicated that the proteins correspond to two defense-related proteins, a myrosinase, TGG2, and a putative ő≤-glucosidase, BGL1. The implications of these observations will be discussed.
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1 - University of Nebraska-Lincoln, Department of Agronomy and Horticulture, 377 Plant Sciences, Lincoln, NE, 68583, USA
2 - University of Nebraska-Lincoln, Department of Biochemistry and Plant Science Initiative
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM