Over-expression of rice OsAGO7 gene induces upward curling of the leaf blade that enhanced erect-leaf habit

High-yield cultivars are characterized by erect leaf canopies that optimize photosynthesis and thus favor increased biomass. Upward curling of the leaf blade (called rolled leaf) can result in enhanced erect-leaf habit, increase erect duration and promote an overall erect leaf canopy. The rice mutant R05, induced through transferred DNA (T-DNA) insertion, had the rolled-leaf trait. The leaves in the wild type demonstrated natural drooping tendencies, resulting in decreasing leaf erection indices (LEIs) during senescence at the 20th day after flowering. Conversely, LEIs of the leaves in R05 remained high, even 20-day post-flowering. We applied T-DNA tagging and isolated a rolled-leaf gene from rice which, when over-expressed, could induce upward curling of the leaf blade. This gene encodes for a protein of 1,048 amino acids including the PAZ and PIWI conserved domains, belonging to the Argonaute (AGO) family. There are at least 18 members of the AGO family in rice. According to high-sequence conservation, the rolled-leaf gene in rice could be orthologous to the Arabidopsis ZIP/Ago7 gene, so we called it OsAGO7. These results provide a possible opportunity for implementing OsAGO7 gene in crop improvement.