| Immunophilins are the receptor of immune response inhibitors in cells.According to the different binding receptors,the immunophilin can be classed into FKBP?FK506banding protein?type and CYP type.In Arabidopsis,for example,there are 52 kinds of immunophilin proteins in total,including 23 of FKBP type and 29 of CYP type,chloroplast contains 17 immunophilins.It can be seen that chloroplasts of Arabidopsis thaliana contain the most cytoplasmic proteins.According to the literatures,CYP38,a immunophilic protein in chloroplasts of Arabidopsis thaliana,plays an important role in the correct assembly and stability maintenance of PSII,thus affecting photosynthesis.So what role does FKBP17-3 play in chloroplasts of Arabidopsis and whether it affects photosynthesis remains to be studied.In thesis,the function of Arabidopsis protein FKBP17-3 was primarily investigated.We used CRISPR-Cas9 gene editing technology to prepare and screen homozygous mutant lines of fkbp17-3,and found that FKBP17-3 expression was terminated prematurely in fkbp17-3 mutant plants.It was found that the homozygous mutant of fkbp17-3 showed the phenotype of early flower,after backcrossed with wild type plants for three generations.We also introduced the wild type FKBP17-3 into the fkbp17-3 mutant plants,and their early flower phenotype was turned back to a normal flower phenotype as wild type through the genetic complementation experiment,indicating that the early flower phenotype was indeed caused by the mutation of FKBP17-3 gene.It was also found that the roots of the fkbp17-3 homozygous mutant were less sensitive to salt and sucrose than the wild type plants,however the sugar content of the fkbp17-3 homozygous mutant was not significantly different from that of the wild type plants.The subcellular localization experiment indicated that the FKBP17-3 was indeed located in the chloroplasts of Arabidopsis thaliana.We further explored whether the early flower phenotype of the homozygous mutant fkbp17-3 was caused by defects in photosynthesis.There was no significant difference in chlorophyll content between the mutant and wild type plants,the results of Blue Native polyacrylamide gel electrophoresis indicated that the mutation of FKBP17-3 may slightly affect the proteins involved in chloroplast photosynthesis.The photoquantum content of PSI and PSII as well as the light response of NPQ were measured with the Dual-PAM-100instrument.It was found that there was no significant difference in the yield of PSI and PSII quantum,and the NPQ value of fkbp17-3 homozygous mutant was lower than that of wild type when the light intensity was lower than 500?mol·m-2·s-1,indicating that fkbp17-3 homozygous mutant may slightly affect some photosynthesis and affect flowering at low light intensity.Both FKBP17-3 and FKBP17-2 was indeed located on the same chloroplasts of Arabidopsis thaliana,and the expressed proteins are also closely related.All the mutants are early-flowering phenotypes.The fkbp17-3A mutant was crossed with the fkbp17-2 mutant to screen the double mutant.It found that when the light intensity is less than 100?mol·m-2·s-1,in front of the same period?between 10 to 15 days?double mutant plants grow bigger than wild type plants,fkbp17-2 mutant,fkbp17-3A strains,and the early flower phenotype of the double mutant were more obvious.This indicates the functional similarity and redundancy of FKBP17-3 and FKBP17-2genes. |
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