Gene network of grain size and number in rice

Abstract

Grain size and number are two key components determining rice yield. As both phenotypes are characterized by quantitative traits, grain size and number are predominantly and tightly controlled by genetic factors. Several quantitative trait loci (QTLs) responsible for grain size and number have been molecularly identified and characterized. These QTLs may act in independent genetic pathways and, along with other identified genes for grain size and number, are mainly involved in the signaling pathways mediated by the ubiquitin-proteasome pathway, G-protein signaling, phytohormones, and transcriptional regulatory factors. Since many of these QTLs and genes were identified from modern elite varieties, they have been strongly selected for enhanced rice productivity in the breeding program. These findings have paved new ways for understanding the molecular basis of grain size and number and enable us to develop the desirable crops with high yield by precise design.