Fu J, Wu H, Ma S, Xiang D, Liu R, Xiong L.

Front Plant Sci. 2017 Dec 11;8:2108. doi: 10.3389/fpls.2017.02108. eCollection 2017.

Abstract

Jasmonates (JAs) and abscisic acid (ABA) are phytohormones known play important roles in plant response and adaptation to various abiotic stresses including salinity, drought, wounding, and cold. JAZ (JASMONATE ZIM-domain) proteins have been reported to play negative roles in JA signaling. However, direct evidence is still lacking that JAZ proteins regulate drought resistance. In this study, OsJAZ1 was investigated for its role in drought resistance in rice. Expression of OsJAZ1 was strongly responsive to JA treatment, and it was slightly responsive to ABA, salicylic acid, and abiotic stresses including drought, salinity, and cold. The OsJAZ1-overexpression rice plants were more sensitive to drought stress treatment than the wild-type (WT) rice Zhonghua 11 (ZH11) at both the seedling and reproductive stages, while the jaz1 T-DNA insertion mutant plants showed increased drought tolerance compared to the WT plants. The OsJAZ1-overexpression plants were hyposensitive to MeJA and ABA, whereas the jaz1 mutant plants were hypersensitive to MeJA and ABA. In addition, there were significant differences in shoot and root length between the OsJAZ1 transgenic and WT plants under the MeJA and ABA treatments. A subcellular localization assay indicated that OsJAZ1 was localized in both the nucleus and cytoplasm. Transcriptome profiling analysis by RNA-seq revealed that the expression levels of many genes in the ABA and JA signaling pathways exhibited significant differences between the OsJAZ1-overexpression plants and WT ZH11 under drought stress treatment. Quantitative real-time PCR confirmed the expression profiles of some of the differentially expressed genes, including OsNCED4, OsLEA3, RAB21, OsbHLH006, OsbHLH148, OsDREB1A, OsDREB1B, SNAC1, and OsCCD1. These results together suggest that OsJAZ1 plays a role in regulating the drought resistance of rice partially via the ABA and JA pathways.

See https://www.ncbi.nlm.nih.gov/pubmed/29312378

Figure 2: Phenotypes of the OsJAZ1-OE plants and the jaz1 T-DNA insertion mutant plants under drought stress treatment at the seedling stage. (A) Schematic diagram of the OsJAZ1 gene and 4A-00845 T-DNA insertion mutant. UTR, ORF, and introns are indicated in the black box, white box, and line, respectively. (B) Expression levels of OsJAZ1 in the 4A-00845 homozygous line and Dongjin. (C) The expression levels of OsJAZ1 in the OE lines and WT ZH11. (D,E) Drought tolerance testing of jaz1 T-DNA mutant plants and over-expression plants. (D) The jaz1 mutant lines showed increased drought resistance. (E) The OsJAZ1-OE plants were more sensitive to drought stress treatment compared to WT ZH11. (F,G) The survival rates of the transgenic and WT plants after recovery from drought stress treatment for 7 days. Mut-1 and mut-2 were heterozygous mutants segregated from 4A-00845. Error bars represent the SE of three replicates (^∗∗∗P < 0.005, Student’s t-test).