Molecular events in senescing Arabidopsis leaves

Molecular events in - The Plant Journal(2004 39 612628 doi 10.1111/j.1365-313X.2004.02160.x Molecular events in senescing Arabidopsis leaves

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Molecular events in senescing Arabidopsis leaves Ji-Feng Lin and Shu-Hsing Wu * Institute of Botany, Academia Sinica, Taipei 11529, Taiwan Received 30 March 2004; revised 15 May 2004; accepted 25 May 2004. * For correspondence (fax 886-2-2782-7954; e-mail [email protected]). Summary Senescence is the fnal stage o± lea± development. Although it means the loss o± vitality o± lea± tissue, lea± senescence is tightly controlled by the development to increase the ftness o± the whole plant. The molecular mechanisms regulating the induction and progression o± lea± senescence are complex. We used a cDNA microarray, containing 11 500 Arabidopsis DNA elements, and the whole-genome Arabidopsis ATH1 Genome Array to examine global gene expression in dark-induced lea± senescence. By monitoring the gene expression patterns at care±ully chosen time points, with three biological replicates each time, we identifed thousands o± up- or down-regulated genes involved in dark-induced senescence. These genes were clustered and categorized according to their expression patterns and responsiveness to dark treatment. Genes with di±±erent expression kinetics were classifed according to di±±erent biological processes. Genes showing signifcant alteration o± expression patterns in all available biochemical pathways were plotted to envision the molecular events occurring in the processes examined. With the expression data, we postulated an innovative biochemical pathway involving pyruvate orthophosphate dikinase in generating asparagine ±or nitrogen remobilization in dark-treated leaves. We also surveyed the alteration in expression o± Arabidopsis transcription ±actor genes and established an apparent association o± GRAS, bZIP, WRKY, NAC, and C2H2 transcription ±actor ±amilies with lea± senescence. Keywords: Arabidopsis , senescence, microarray, pyruvate orthophosphate dikinase, transcription ±actor, biochemical pathway. Introduction Unable to ±ee the habitat in which they grow, plants proceed with senescence in a highly coordinated manner (Buchanan- Wollaston et al. , 2003; Gan, 2003; Lim et al. , 2003; Quirino et al. , 2000; Yoshida, 2003). Many biotic and abiotic stresses also trigger senescence. Processes associated with leaf senescence include the disorganization of chloroplasts, shrinkage of cytoplasmic volume and decrease in cellular metabolic activities. Signi²cant metabolic changes are involved in the degeneration and remobilization of macro- molecules that accumulate during growth and maturation. Research efforts to reveal the underlying molecular mechanism of plant senescence began with the collecting and analyzing of senescence-associated genes (SAGs). Sequence and/or functional analyses revealed that SAG-encoded proteins include proteases, nucleases, lipid-, carbohydrate- and nitrogen-metabolizing enzymes, stress- responsive proteins, and transcriptional regulators (for review see Buchanan-Wollaston et al. , 2003). Previous studies have shown that SAGs have common and distinct expression pro²les in response to various senescence- inducing factors (He et al.
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This note was uploaded on 08/01/2009 for the course 2231 22444 taught by Professor Park during the Spring '09 term at A.T. Still University.

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Molecular events in - The Plant Journal(2004 39 612628 doi 10.1111/j.1365-313X.2004.02160.x Molecular events in senescing Arabidopsis leaves

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