Robust increase of leaf size in Arabidopsis thaliana by GRF3-like transcription under different growth conditions

BELTRAMINO, M; PALATNIK JF

Scientific Reports

Springer Nature

Año: 2018

n increase in crop yield, especially under sub-optimal conditions, is essential to reassurefood security to meet the accelerating global demand. Several genetic modifications havebeen shown to increase organ size, which in turn might boost crop yield. Still, only in a fewcases their performance has been evaluated under stress conditions. MicroRNA (miRNA)miR396 repress the expression of GROWTH-REGULATING FACTOR (GRF) genes, transcriptionfactors that promote organ growth in plants. This study describes the role of the miR396regulatory network in the control of organ size in plants under normal and stress conditions.We show that both Arabidopsis thaliana At-GRF2 and At-GRF3 genes resistant to miR396activity (rGRF2 and rGRF3) increased organ growth, but only rGRF3 can increase leaf sizewithout causing detrimental morphological defects. Furthermore, At-rGRF3 can increase leafsize, root length and seed size when expressed in Brassica oleracea, and At-rGRF3 homologsfrom soybean and rice increase leaf size in Arabidopsis, suggesting that regulation of GRF3activity is important for organ growth in a broad range of species. Plants harboring rGRF3have larger leaves than wild-type plants also under moderate drought stress, a condition thatstimulates miR396 accumulation. At-rGRF3 plants showed a mild increase in the resistance tovirulent bacteria, suggesting that the enhancement of growth promoted by rGRF3 can occurwithout an obvious cost on plant defenses. Our findings indicate that rGRF3 can increase plantbiomass under both normal and stress conditions, and therefore could be considered as avaluable tool for biotechnological applications.