Feedback Regulation of ABA Signaling and Biosynthesis by a bZIP Transcription Factor Targets Drought-Resistance-Related Genes

Abstract

The OsbZIP23 transcription factor has been characterized for its essential role in drought resistance in rice (Oryza sativa), but the mechanism is unknown. In this study, we first investigated the transcriptional activation of OsbZIP23. A homolog of SnRK2 protein kinase (SAPK2) was found to interact with and phosphorylate OsbZIP23 for its transcriptional activation. SAPK2 also interacted with OsPP2C49, an ABI1 homolog, which deactivated the SAPK2 to inhibit the transcriptional activation activity of OsbZIP23. Next, we performed genome-wide identification of OsbZIP23 targets by immunoprecipitation sequencing and RNA sequencing analyses in the OsbZIP23-overexpression, osbzip23 mutant, and wild-type rice under normal and drought stress conditions. OsbZIP23 directly regulates a large number of reported genes that function in stress response, hormone signaling, and developmental processes. Among these targets, we found that OsbZIP23 could positively regulate OsPP2C49, and overexpression of OsPP2C49 in rice resulted in significantly decreased sensitivity of the abscisic acid (ABA) response and rapid dehydration. Moreover, OsNCED4 (9-cis-epoxycarotenoid dioxygenase4), a key gene in ABA biosynthesis, was also positively regulated by OsbZIP23. Together, our results suggest that OsbZIP23 acts as a central regulator in ABA signaling and biosynthesis, and drought resistance in rice.

Sporobolus stapfianus: Insights into desiccation tolerance in the resurrection grasses from linking transcriptomics to metabolomics

“…This was exemplified by the accumulation of transcripts encoding an ABA-activated serine/threonine-protein kinase SAPK6, protein phosphatase 2C, and CBL-interacting protein kinases (as discussed earlier). Serine/threonine-protein kinase SAPK6 phosphorylates bZIP transcription factors that regulate downstream gene expression events associated with responses to water-deficit stress and are inactivated by protein phosphatase 2C [94]. In concordance with the transcriptome, the elevated endogenous ABA levels (Fig.…”

An R2R3‐MYB transcription factor represses the transformation of α‐ and β‐branch carotenoids by negatively regulating expression of CrBCH2 and CrNCED5 in flavedo of Citrus reticulate

“…The electrophoretic mobility shift (EMSA) assay was conducted as described previously (Liu et al ., ; Zong et al ., ) with some modifications. Briefly, the His‐fused CrMYB68 was expressed and purified as described earlier.…”

“…Owing to the high stability, transformation efficiency and short growth cycle, the dual luciferase transcriptional activity assay was conducted using rice protoplasts as described previously (Zong et al ., ). The rice sheath strips from 14‐d‐old seedlings of ZH11 ( Oryza sativa spp .…”

Rice Homeodomain Protein WOX11 Recruits a Histone Acetyltransferase Complex to Establish Programs of Cell Proliferation of Crown Root Meristem

“…Plasmids containing 35S:GCN5-HA:NOS-terminator, 35S:ADA2:NOSterminator (with ADA2 cDNA in either sense or antisense direction), 35: GFP:NOS-terminator, or 35S:WOX11-GFP:NOS-terminator fragments were transformed via polyethylene glycol method into rice shoot cell protoplasts prepared from 10-d-old wild-type seedlings as described (Zong et al, 2016). After 16 h cultivation, protoplasts were harvested and broken by centrifugal force; GFP-Trap beads (ChromoTek; gta-20) were incubated with supernatant of the protoplasts overnight at 4°C.…”