Expression Analysis of Genes Related to Oxidative Protection During Senescence in Brassica napus

Abstract

Leaf senescence is the sequence of events leading to cellular disassembly and mobilization of released<br />materials that cause accumulation of reactive oxygen species. DNA sequencing of one of senescence-isolated<br />cDNA, LSC650, showed a high level of similarity with a catalase gene of Arabidopsis. Transcript level of<br />this isoform was highly increased during senescence. The enzyme activity of catalase was also assayed during<br />different developmental stages in Brassica napus and showed a high level of activity during last part of<br />leaf senescence. Both kinetic assay and northern analysis exhibit that catalase has the potential to play<br />a significant role in the cell defense against produced hydrogen peroxide as part of the macromolecules<br />breakdown. Gene expression pattern was characterized by mRNA hybridization with several antioxidant<br />cDNA clones. Transcript levels of discussed genes were markedly increased during senescence stages.<br />We conclude that the major part of the mRNA changes observed during senescence stages of leaves is connected with leaf senescence, whereas free radicalrelated transcripts appear to protect cells from oxidative<br />damage.<br /><br />