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

Abstract

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.

Rice leaf inclination2, a VIN3-like protein, regulates leaf angle through modulating cell division of the collar

“…The pair of antagonistic HLH/bHLH transcription factors, ILI1 and IBH1, mediates the BR regulation of lamina inclination in rice [25]. In addition, increased expression of the OsAGO7 gene, the ortholog of the Arabidopsis ZIPPY (ZIP/AGO7, belonging to the Argonaute family), resulted in the upward curling of the leaf blade and enhanced erectness of the leaf [26].…”

Genetic modification of plant architecture and variety improvement in rice

“…ARGO-NAUTE1 (AGO1), a component of the RNA silencing machinery, is also required for dorsoventrality of leaves by the proper regulation of miRNA165/166, which targets the Genetic control of rice plant architecture X-C Yang and C-M Hwa cleavage of the HD-ZIPIII mRNAs (Kidner and Martienssen, 2004). There are at least 18 members of the AGO family in rice (Shi et al, 2007). One rolled-leaf gene, RL(t), belonging to the Argonaute (AGO) family, is located to a region of about 137 kb on the long arm of chromosome 2 of rice (Shao et al, 2005).…”

“…One rolled-leaf gene, RL(t), belonging to the Argonaute (AGO) family, is located to a region of about 137 kb on the long arm of chromosome 2 of rice (Shao et al, 2005). Shi et al (2007) recently reported that OsAGO7, a member of the rice AGO gene family, encodes a 1048 amino acid protein containing both PAZ and PIWI domains. Overexpression of this gene in rice induced upward curling of the leaf blade.…”

The Cornucopia of Small RNAs in Plant Genomes

“…Another important component of the small RNA machinery is represented by the set of Argonaute proteins. There are ten conserved members in Arabidopsis and at least 18 members in rice [69,70]. Phylogenetic analysis of the Argonaute family demonstrates that most of the diversification in rice compared to Arabidopsis took place in the AGO1 and AGO5 clades (Fig.…”

“…OsAGO7, which is believed to be orthologous to the Arabidopsis ZIP/AGO7 gene (Fig. 5), facilitates upward curling of leaves when over-expressed in rice [69]. In a study performed by Nagasaki et al [14], the rice genes known as SHOOTLESS2 (SHL2), SHL4/SHOOT ORGANIZATION2 (SHO2), and SHO1, encoding orthologs of the small RNA-associated Arabidopsis proteins RNAdependent RNA polymerase 6 (RDR6), AGO7, and DCL4, respectively, were shown to play a role in leaf development through the ta-siRNA pathway.…”