Identification of a regulatory element responsible for salt induction of rice OsRAV2 through ex situ and in situ promoter analysis.
Salt is a major environmental stress factor that can affect rice growth and yields. Recent studies suggested that members of the AP2/ERF domain-containing RAV (related to ABI3/VP1) TF family are involved in abiotic stress adaptation. However, the transcriptional response of rice RAV genes (OsRAVs) to salt has not yet been fully characterized. In this study, the expression patterns of all five OsRAVs were examined under salt stress. Only one gene, OsRAV2, was stably induced by high-salinity treatment. Further expression profile analyses indicated that OsRAV2 is transcriptionally regulated by salt, but not KCl, osmotic stress, cold or ABA (abscisic acid) treatment. To elucidate the regulatory mechanism of the stress response at the transcriptional level, we isolated and characterized the promoter region of OsRAV2 (P OsRAV2 ). Transgenic analysis indicated that P OsRAV2 is induced by salt stress but not osmotic stress or ABA treatment. Serial 5' deletions and site-specific mutations in P OsRAV2 revealed that a GT-1 element located at position -664 relative to the putative translation start site is essential for the salt induction of P OsRAV2 . The regulatory function of the GT-1 element in the salt induction of OsRAV2 was verified in situ in plants with targeted mutations generated using the CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9) system. Taken together, our results indicate that the GT-1 element directly controls the salt response of OsRAV2. This study provides a better understanding of the putative functions of OsRAVs and the molecular regulatory mechanisms of plant genes under salt stress.
Key Laboratory of Rice Genetic Breeding of Anhui Province, Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031, China.|Key Laboratory of Resource Plant Biology of Anhui Province, College of Life Sciences, Huaibei Normal University, Huaibei, 235000, China.
Yong-Bo
YB
Duan
Key Laboratory of Rice Genetic Breeding of Anhui Province, Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031, China.
Juan
J
Li
Key Laboratory of Rice Genetic Breeding of Anhui Province, Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031, China.
Rui-Ying
RY
Qin
Key Laboratory of Rice Genetic Breeding of Anhui Province, Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031, China.
Rong-Fang
RF
Xu
Key Laboratory of Rice Genetic Breeding of Anhui Province, Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031, China.
Hao
H
Li
Key Laboratory of Rice Genetic Breeding of Anhui Province, Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031, China.
Ya-Chun
YC
Yang
Key Laboratory of Rice Genetic Breeding of Anhui Province, Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031, China.
Hui
H
Ma
Key Laboratory of Rice Genetic Breeding of Anhui Province, Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031, China.
Li
L
Li
Key Laboratory of Rice Genetic Breeding of Anhui Province, Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031, China. weipengcheng@gmail.com.
Peng-Cheng
PC
Wei
Key Laboratory of Rice Genetic Breeding of Anhui Province, Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031, China. yjianbo@263.net.
Jian-Bo
JB
Yang
D000222:Adaptation, Physiological; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D012275:Oryza / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D055049:Salt Tolerance; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological
D010940:Plant Proteins; D012965:Sodium Chloride
CRISPR/Cas9; GT-1element; RAV; Rice; Salt response