Location: Plant Physiology and Genetics ResearchTitle: Overexpression of transcription factor OsWR2 1 regulates wax/cutin biosynthesis and enhances drought tolerance in rice) Author
Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/27/2013
Publication Date: N/A
Citation: Interpretive Summary: Drought is the major environmental stress limiting crop production, and the plant cuticle represents the outer-most covering of the plant that prevents uncontrolled water loss and protects the plant from drying out during climatological drought. We report here studies on a new gene from rice (OsWR2) that controls the synthesis of both cuticular wax and cutin biosynthesis in rice cuticle. Altering the amount of expression of OsWR2 in rice had a large effect on wax and cutin chemical composition, providing evidence that OsWR2 controls the expression of cuticle genes. When this gene was overexpressed for example, 19 other genes that were previously associated with wax and cutin biosynthesis were expressed at higher levels as well. Also, OsWR2 overexpression improved rice drought tolerance, and this by changing the permeability of the cuticle to water loss. These results show that OsWR2 regulates both wax and cutin biosynthesis, and plays a major role in controlling cuticle permeability and overall plant drought tolerance.
Technical Abstract: Drought is the major abiotic stress limiting crop production. Plant cuticle represents the outer-most layer of the epidermis and previous studies demonstrate its association with plant response to climatological drought. We report here the functional characterization of the rice ((Oryza sativa L.) Wax Synthesis Regulatory 2 gene (OsWR2), a homolog of both the AP2/EREBP transcription factor gene WIN1/SHN1 in Arabidopsis and the OsWR1 gene in rice. OsWR2 showed high expression in epidermal tissues and contributed to the transcriptional regulation of both cuticular wax and cutin biosynthesis in rice cuticle. Overexpression of OsWR2 in rice increased the total cuticular wax level by 48.6% in leaves and by 72.4% in panicles. Alkanes and aldehydes were the main increased wax components, suggesting OsWR2 may play a major role in wax decarbonylation pathway. The total cutin amount was increased by 48.1% in leaves and 65.9% in panicles of OsWR2 overexpression rice due primarily to an increase in hydroxylated cutin monomers, suggesting the involvement of OsWR2 in cutin monomer hydroxylation. Nineteen genes putatively involved in wax and cutin biosynthesis were up-regulated in OsWR2 overexpressors. Furthermore, OsWR2 overexpression rice showed reduced cuticle permeability as supported by decreased leaf chlorophyll leaching, lower water loss rate and enhanced drought tolerance. OsWR2 overexpression rice had higher free proline and lower malondialdehyde contents under water deficit stress. These results demonstrate that OsWR2 regulates both wax and cutin biosynthesis in a mechanism other than WIN1/SHN1 and OsWR1, and plays a major role in controlling cuticle permeability and overall plant drought tolerance.