The effect of environmental stress events on the mobility of four LTR retrotransposon families in grapevine (Vitis vinifera) somatic embryo cultures

The long terminal repeat (LTR) regions of class I transposable elements in plants contain regulatory elements common to the promoters Of stress-response genes. Accordingly, expression levels of several transposon families have previously been shown to increase in response to environmental stresses in model species. In this study we analyze the genomic variation resulting from the stimulation of endogenous transposons in grapevine. Somatic embryo cultures of Vitis vinifera cultivars Chardonnay and Pinot noir were regenerated after exposure to a variety of environmental stresses (temperature / UV / osmotic shock and pathogen exposure). Genomic DNA was extracted from young regenerated plantlets and analyzed by sequence-specific amplified polymorphism (S-SAP) transposon display. Simultaneous screening of four endogenous transposon families was achieved by labeling each with distinct fluorescent dyes during amplification. Insertion profiles were then recorded by multiplex capillary electrophoresis. We compare the relative mobility of the transposon families following stress events and plantlet regeneration. The differential activation of endogenous transposon families demonstrates the potential of environmental forces to stimulate transposon mutagenesis in an important agricultural crop