Expression pattern analysis of Will Die Slowly genes in Arabidopsis

Leaf senescence is a developmental programmed cell death (PCD) that occurs as a response to external and internal signals. Several factors, such as the environment, plant hormones, and senescence-associated genes, regulate leaf senescence. In Drosophila melanogaster, Will Die Slowly (WDS) is a WD-repeat protein, which is closely related to PCD. Phylogenetic analysis indicated that eight genes are highly homologous to D. melanogaster WDS (DmWDS) in Columbia ecotype (Col) of Arabidopsis thaliana. In this study, the expression patterns of three close homologues of DmWDS named WDS1, WDS2, and WDS3 were investigated. Real-time PCR revealed the spatio-temporal expression levels of these three genes. No tissue-specific expression of the three AtWDS genes was observed. These genes were expressed at every growth stage; the variation in their expression was similar: the expression of the three AtWDS reached the peak in leaves at the 37 days after sowing, at the time when the first pod initially appeared on the plant and the leaf 7 show 25 to 50% yellow; and the expression of the three AtWDS reached the peak in flowers at the 43.5 days after sowing, at the time when 50% of the flowers bloomed. In addition, the expression level of the three AtWDS peaked at the 48 h after the plants were treated with 0.5 mM salicylic acid (SA). WDS3 also exhibited a high expression at 24, 48, and 72 h. Taken together; these results suggest that AtWDS genes may be involved in plant PCD