Hyunmi Kim1,*, Kyeyoon Lee1,*, Hyunsik Hwang1,*, Nikita Bhatnagar2,3, Dool-Yi Kim1, In Sun Yoon1, Myung-Ok Byun1, Sun Tae Kim4, Ki-Hong Jung2,3 and Beom-Gi Kim1,†
1 Molecular Breeding Division, National Academy of Agricultural Science, RDA, Suwon 441-707, Republic of Korea
2 Department of Plant Molecular Systems Biotechnology and Crop Biotech Institute, Kyung Hee University, Yongin 446-701, Republic of Korea
3 Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701, Republic of Korea
4 Department of Plant Bioscience, Pusan National University, Miryang, 627-706, Republic of Korea
* These authors contributed equally to this manuscript.
† To whom correspondence should be addressed.
Abscisic acid (ABA) is a phytohormone that plays important roles in the regulation of seed dormancy and adaptation to abiotic stresses. Previous work identified OsPYL/RCARs as functional ABA receptors regulating ABA-dependent gene expression in Oryza sativa. OsPYL/RCARs thus are considered to be good candidate genes for improvement of abiotic stress tolerance in crops. This work demonstrates that the cytosolic ABA receptor OsPYL/RCAR5 in O. sativa functions as a positive regulator of abiotic stress-responsive gene expression. The constitutive expression of OsPYL/RCAR5 in rice driven by the Zea mays ubiquitin promoter induced the expression of many stress-responsive genes even under normal growth conditions and resulted in improved drought and salt stress tolerance in rice. However, it slightly reduced plant height under paddy field conditions and severely reduced total seed yield. This suggests that, although exogenous expression of OsPYL/RCAR5 is able to improve abiotic stress tolerance in rice, fine regulation of its expression will be required to avoid deleterious effects on agricultural traits.
Key words : ABA receptors, drought stress, rice, salt stress