Pre-harvest sprouting (PHS) is the premature germination of grains which causes significant economic loses to both growers and end-users. Breeding for PHS resistance is challenging due to genetic complexity and phenotyping difficulties. Our group has demonstrated that AGO4_9 (Argonaute4_9) is associated with PHS in both barley and wheat. AGO4_9 is a member of RNA-directed DNA methylation (RdDM) pathway and involved in the regulation of DNA methylation in plants.

Our current efforts involve, first, identifying the RdDM pathway gene families in small grain cereals, including barley, wheat, and two progenitors of wheat. Spatiotemporal expression of key genes including AGO, Pol, HEN1, RDR and DCL indicated their up-regulation during seed development. This corresponds to the results obtained from comprehensively studied species Arabidopsis, thus highlights the vital and conserved role of RdDM in the phases of seed development including dormancy and germination. Secondly, we are developing methodologies to further characterize the specific role of AGO4_9 on seed developmental phase in barley, either by temporarily inhibiting its expression via antisense oligonucleotides (ODNs), or through stable transgenic RNAi approaches. The AGO-PHS association could provide a new prospective to understand the seed physiology, and expedite the efforts in the development of novel markers for breeding of vigorous PHS-resistant crops.