Two novel strategies to assess in vivo meiotic protein expression in Arabidopsis thaliana

For studies on key meiotic processes such as crossover formation and genome haploidization, the availability of portable promoter sequences for effector protein expression in meiocytes is of great importance. In this study, we present two novel strategies to facilitate screening for such promoter elements. The first strategy was based on expression of a previously constructed GFP-tagged zinc finger protein for visualization of the pericentromeric regions of chromosomes in meiocytes. Here, we show that expression of this reporter protein under control of different promoters allowed for the visualization of fluorescence foci in meiocytes, demonstrating that this is a useful tool for such purposes. The second reporter system was based on the visualization of cytotoxicity triggered by expression of the Agrobacterium tumefaciens virulence protein VirD5. We show that constitutive expression of VirD5 is lethal, but when driven by meiotic promoters led to reduced fertility with normal vegetative growth. We show that both strategies offer useful tools for the assessment of meiotic effector protein expression, especially when combined with available gene expression data sets.