Grain Sprouting: Is Epigenetics Playing a Role?

Among various functional genomic tools to characterize genes in plants, transposon-based approach offers great potential, especially in barley and wheat, which possess large genomes and genetic transformation is not a routine.  Transposons also served as building block for epigenetic gene control due to their ability to recruit the silencing machinery.  Using transposon vehicles, we are exploring cereal genes involved in various stages of plant development especially seed dormancy and pre-harvest sprouting.  We employed transposon- and synteny- based approaches to dissect important QTL region of barley. Our barley-rice synteny approach detected 24 candidate ESTs, two of which show polymorphism and differential gene expression during early seed germination in different barley genotype. In addition, a key gene of RdDM pathway, ARGONAUTE4_9 has been found to be associated with Pre-harvest Sprouting in barley and wheat. Significant variation in the expression of AGO4_9 class genes in dormant and non-dormant barley and wheat genotypes was observed. This data along with DNA methylation changes suggest that AGO4_9 class may be acting as an epigenetic switch during seed development and seed dormancy.  Taken together, this will allow us to further understand the potential epigenetic role in seed development and germination.