The Function Of AaMYB117 Gene In Actinidia Arguta Under Low Temperature Stress

Actinidia arguta is an economic large deciduous perennial vine of the genus kiwifruit of the kiwifruit family,which has high economic and health value.However,low temperature is one of the main environmental factors limiting the planting of A.arguta.Therefore,it is beneficial to the development of A.arguta industry to study the resistance mechanism of A.arguta to low temperature.In this study,transcriptome sequencing technology was used to explore the mechanism of frost resistance of A.arguta,identify and analyze the regulatory pathways and related transcription factors in response to low temperature stress.And the AaMYB transcription factor family of A.arguta was identified and analyzed.At the same time,the key gene AaMYB117 was screened.And the AaMYB117 gene was transformed into the leaves of A.arguta and Arabidopsis thaliana,and the relevant functional verification was carried out.The main results are as follows:1.A.arguta was treated at low temperature,and the buds treated for 0 h,2 h and 6 h were sampled and sequenced.A total of 1454 different expressed genes(DEGs)were identified.DEGs are mainly concentrated in GO items such as transcription regulator activity,DNAbinding transcription factor activity and tetrapyrrole binding.And DEGs are mainly concentrated in pathways such as plant hormone signal transduction,starch and sucrose metabolism,inositol phosphate metabolism and phosphatidylinositol signaling system.A total of 124 transcription factors were identified by DEGs,belonging to 29 gene families such as AP2/ERF,MYB and b HLH.2.Because MYB transcription factor plays an important role in response to low temperature stress,the AaMYB gene family of A.arguta was further analyzed.Based on transcriptome data,101 members of the AaMYB family were identified,including 40 1R-MYB,56 R2R3-MYB,4 3R-MYB,and 1 4R-MYB.The physical and chemical properties,phylogenetic relationships and conserved motifs of the AaMYBs were further analyzed,and the AaMYBs were divided into 22 subfamilies.The expression pattern of AaMYBs under low temperature stress indicated that some AaMYB genes may play an important role in the response of A.arguta to low temperature stress.3.The ORF sequence of AaMYB117 in A.arguta is 933 bp,encoding 310 amino acids,and contains two myb-domains,belonging to R2R3-MYB.Subcellular localization experiments showed that AaMYB117 was localized in the nucleus and cytoplasm.The plant expression vector 35S::AaMYB117 was constructed to obtain transgenic leaves of A.arguta by transient transformation and transgenic A.thaliana by stable genetic transformation.Under low temperature stress,the expression levels of AaCBF and downstream AaCORs genes and Fv/Fm in transgenic leaves of A.arguta were lower than those in the control,while the ROS content was higher than that in the control.The expression levels of At CBFs and At CORs genes,Fv/Fm,antioxidant enzyme activity and proline content of transgenic A.thaliana were lower than those of the control,while the ion permeability,MDA content and ROS content were higher than those of the control.These results indicated that overexpression of AaMYB117 reduced the frost resistance of A.arguta leaves and A.thaliana by inhibiting the expression of CBF and CORs genes.4.AaMYB117 has transcriptional activation activity by yeast two-hybrid experiment.The interaction between AaMYB117 and Aab HLH137 was confirmed by yeast two-hybrid experiment and double-luciferase experiment.