Investigating the role of the GRF4 gene in barley and durum wheat

The expansion of human population in the next 50 years will require double the production of cereals and will put a strong pressu agricultural systems. Actions are needed, new breeding strategies knowledge on genes related to yield increase are fundamental. Our group is focusing on studying genes that can be manipulated to achieve a bet yield potential and one of the candidate genes belongs to the Gro Regulating Factor G(RF) family. GRFs are plant specific transcription factors sharing two highly conserved domains named QLQ and WRC; t proteins play vital roles in plant development and stress response. GRF proteins interact with their cofactors: GIF (GRF Interacting Factor) further bind the DNA and to regulate the expression of target g Previous studies showed thatGRF4 in O. sativa controls seed size an promotes nitrogen assimilation and carbon fixation. The balance between the GRF4 and DELLA proteins controls plant growth and metabolism of C and N for this reason, genetic variation of GRF4 (and orthologues) might become a major target for breeders in enhancing crop yield and nutri efficiency. The expression ofGRF4 occurs at different levels comprising the N availability and the activity of miR396. Focusing on barley and durum wheat, we have identified 18GRF sequences in H. vulgare cultivar Golden Promise and 31 in T. durum; we are currently interested in the functional characterization of theHvGRF4 andTdGRF4 genes. To this aim, we set up different experimental plans through genome editing, ectopic expression and fine mapping approaches using RIL lines. Exploiting the CRISPR technology we producedgrf4 mutants inHordeum vulgare Golden Promise genetic background and we transformed barley plants with a construct fo the homologous recombination to abolish the miR396 regulation. Furthermore, when we ectopically expressed the GRF4 gene in barley plants we observed an increase in seed length and a delay in flowering time. Phenotyping a molecular data will be presented.