Arabidopsis CK2-HY5 Signaling Module Regulates The Expression Of ABA-response Genes

Climate warming has increased the global weather disasters year by year.The drought is the most severe meteorological disaster which greatly affects the production of agriculture and the output of crops in C hina.The large accumulation of plant hormone abscisic acid(ABA)is an important feature of plants responding to drought stress and then initiate plant protection mechanisms.Casein K inase?(CK2)is an evolutionarily conserved Ser/Thr protein kinase,is commonly found in eukaryotes.In plants,CK2 regulates multiple developmental and stress response processes.In mammals,CK2 is generally composed of two ?-subunits and two ?-subunits,to form a tetramer to play role.In Arabidopsis,CK2 composes of four genes encoding the ? catalytic subunits(CKA1-CKA4)and four genes encoding the ? regulatory subunits(CKB1-CKB4).Until now,there are no systematic reports on how CK2 regulates the ABA response network of plants.In this study,we used cka loss-of-function mutants and multidisciplinary experimental techniques to explore ABA early response pathway networks in Arabidopsis.The main conclusions of this study are as follows:(1)By using microscope observation,we found that CKA1,CKA2,and CKA3 localize in nucleus and cytoplasm,and CKA4 localizes in chloroplasts.(2)cka loss-of-function mutants displayed ABA low sensitivity phenotypes comparing to wild type.And CKA1,CKA2,and CKA3 play redundant roles.(3)Using GO analysis on RNA-seq of cka-tri mutant after ABA treatment,showed many up-regulated genes are enriched in light response pathway,can be recognized by HY5,CKA and HY5 may regulate the ABA-responsive genes.(4)By RN A-seq analysis of ABA-treated hy5 and cka-tri mutants,it was found that most downstream differentially expressed genes of CKA and HY5 overlap,CKA and HY5 may jointly regulate the ABA response genes expression.(5)Using C RISPR-Cas9 technology we obtained cka-tri/hy5 mutants.Observe phenotypes after ABA treatment,showed a low sensitivity to ABA.Which proves that HY5 is in Downstream of CK2 genetics jointly regulates the ABA response pathway.(6)To explore the molecular mechanisms,we have demonstrated CKA interacts with HY5 in vitro and in vivo by using BiFC,Co-IP and Pull-down experiments.Based on the above results,we inferred that CKA and HY5 co-regulate genes expression in the ABA response pathway in the same signaling pathway.O ur results partially lays the foundation for systematically explaining how casein kinase ? participates in the regulation of plant ABA response.