Mechanisms Of SERKs Regulating Seed Germination By ABA Signaling And Screening Of Their Interaction Proteins

Receptor kinases SOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASE(SERKs)are involved in the regulation of many life activities.It was found that AtSERKs play an important role in regulating the development of Arabidopsis embryos.The serk1/2/3 triple mutant displays delayed germination and aberrant embryo development.Physiological experiments revealed that the serk1/2/3 mutant is hypersensitive to ABA and the seed germination is significantly inhibited.The serk1/3 mutant and the serk2/3 mutant are also hypersensitive to ABA.The expression levels of ABA INSENSITIVE 5(ABI5),PYR1-LIKE 2(PYL2),DELAY OF GERMINATION 1(DOG1),three ABA signaling pathway-related genes,were significantly changed in serk1/2/3 mutants.Loss function of SnRK2.2 and SnRK2.3 can attenuate the ABAhypersensitive phenotypes of the serk1/2/3 mutants.It is suspected that SERKs may interact with PP2 Cs,regulate the kinase activity of downstream SnRKs,and phosphorylate downstream transcription factors(such as ABI5)to regulate seed germination.The yda and mkk4/5 mutants have defects similar to the serk1/2/3 mutant during embryo development.SERK-mediated signals are transduced via the MPK cascade to control embryo development.However,SERKs cannot directly interact with YDA,and there must be other signaling components that transmit signals from SERKs to downstream YDA.We hypothesized that a group of cytoplasmic receptor kinases are involved in this process.To identify these cytoplasmic receptor kinases,we used yeast two-hybrid technique to screen RLCKs that can interact with SERKs,and explored the expression patterns of RLCKs through eFP Browser that can express in embryo.The subfamilies of RLCK XVII,RLCK X,RLCK ? were finally found.We ordered T-DNA insertion lines of RLCK588,RLCK590,RLCK591,and the RLCK589 gene was edited by Crispr-Cas9 technology.The quadruple mutant rlck588/589/590/591 was constructed by genetic hybridization.Phynotypic analyses indicated that the quadruple mutant can grow normally.Promoter expression analyses showed that RLCK588 and RLCK591 were expressed in stomata,suggesting that members of the RLCK X subfamily may be involved in the ABA signaling pathway.