Poster: Late and Moved Abstracts

Abs # 985: Molecular events in senescing Arabidopsis leaves.

Presenter:	Wu, Shu-Hsing , shuwu@gate.sinica.edu.tw
Authors	Wu, Shu-Hsing  (A)   Lin, Ji-Feng  (A)
Affiliations:	(A): Institute of Botany, Academia Sinica

Senescence is the final stage of leaf development. Though it seems to be the loss of vitality of leaf tissue, leaf senescence is tightly controlled by development to increase the fitness of the whole plant. The molecular mechanisms regulating the induction and progression of leaf 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 leaf senescence. By monitoring the gene expression patterns at carefully chosen time points, with 3 biological replicates at each time, we identified thousands of 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 different expression kinetics were classified according to separate biological processes. Genes showing significant alteration of 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 (PPDK) in generating asparagine for nitrogen remobilization in dark-treated leaves. We also surveyed the alteration in expression of Arabidopsis transcription factor genes and established an apparent association of GRAS, bZIP, WRKY, NAC and C2H2 transcription factor families with leaf senescence.