RETRACTED: OST1 Activation by the Brassinosteroid-Regulated Kinase CDG1-LIKE1 in Stomatal Closure

Abstract

Crosstalk between signaling pathways is an important feature of complex regulatory networks. How signal crosstalk circuits are tailored to suit different needs of various cell types remains a mystery in biology. Brassinosteroid (BR) and abscisic acid (ABA) antagonistically regulate many aspects of plant growth and development through direct interactions between components of the two signaling pathways. Here, we show that BR and ABA synergistically regulate stomatal closure through crosstalk between the BR-activated kinase CDG1-LIKE1 (CDL1) and the OPEN STOMATA1 (OST1) of the ABA signaling pathway in We demonstrate that the mutant displayed reduced sensitivity to ABA in a stomatal closure assay, similar to the mutant. CDL1 and the BR receptor BR-INSENSITIVE1, but not other downstream components of the BR signaling pathway, were required for BR regulation of stomatal movement. Genetic and biochemical experiments demonstrated that CDL1 activates OST1 by phosphorylating it on residue Ser-7. BR increased phosphorylation of OST1, and the BR-induced OST1 activation was abolished in mutants. Moreover, we found that ABA activates CDL1 in an OST1-dependent manner. Taken together, our findings illustrate a cell-type-specific BR signaling branch through which BR acts synergistically with ABA in regulating stomatal closure.

CDL1-OST1 Interaction as a Focal Point of Brassinosteroid-Abscisic Acid Hormone Signaling Crosstalk

“…ABA-induced stomatal closure depends on OST1 (Mustilli et al, 2002). What Kim et al (2018) found is that the ost1 mutant is also insensitive to BRmediated stomatal closure, phenocopying the cdl1 mutant. With these solid phenotypic characterizations on hand, they investigated a possible mechanism by which both CDL1 and OST1 mediate the stomatal response.…”

“…Because the authors show that CDL1 is preferentially expressed in the leaf guard cells, this protein-protein interaction and eventual transphosphorylation mechanism indicate that BR and ABA cooperate in a synergistic manner in modulating the stomatal closure response. (Adapted from Kim et al [2018], Figures 4A and 4B…”

“…Although their respective signal transduction pathways have been elucidated from hormone perception to transcriptional regulation, the nature of the BR-ABA interaction during the response to environmental stimuli (e.g., stomatal closure) remains unclear. In their study, Kim et al (2018) demonstrate that, in contrast to their roles in growth and development, BR and ABA regulate stomatal closure in a synergistic fashion. This synergism is mediated through the newly discovered interaction between the BR-associated CDG1-LIKE1 (CDL1) and ABA-associated OPEN STOMATA1 (OST1) (see figure).…”

Identification of key modules and hub genes regulating drought stress response in rice drought sensitive line PY6 by weighted gene co-expression network analysis

“…More intriguingly, photosynthesis rate was found to be declined under drought stress, especially in drought sensitive genotype, suggesting that the enhancement of antioxidant capacity was in favor of maintaining higher photosynthetic activity, and thereby would improve drought resistance of plants (Zhang et al 2016). Moreover, phytohormone signaling and Ca 2+ signaling were also highlighted in transcript pro ling and revealed the cross-talk among phytohormone signaling pathways (Kim et al 2018;LY et al 2014). In addition, a large number of transcription factor families, like WRKY, bZIP, and MYB, were identi ed involved in ABA-mediated signaling transduction under abiotic stresses (Borah et al 2017;Okay et al 2014).…”

Weighted Gene Coexpression Network Analysis-Based Identification of Key Modules and Hub Genes that Regulate the Drought Stress Response in the Rice Drought-Sensitive Line PY6

“…Intriguingly, the photosynthesis rate was found to decline under drought stress, especially in drought-sensitive genotypes, suggesting that the enhancement of antioxidant capacity favors maintaining a higher photosynthetic activity and thereby improves the drought resistance of plants [36]. Moreover, phytohormone signaling and Ca 2+ signaling have also been highlighted in transcript pro ling and have been revealed cross-talk among phytohormone signaling pathways [37,38]. In addition, a large number of transcription factor families, such as WRKY, bZIP, and MYB families, were found to be involved in ABA-mediated signal transduction under abiotic stress [39,40].…”