Primary Research On The Function Of Lipid Transfer Protein 7(LTP7) In Arabidopsis

Lipid transporters or lipid transfer proteins(LTPs)family is a class of soluble proteins with a molecular weight less than 10 k Da.LTPs usually have 4 to 5 ?-helices,and 4 stable disulfide bonds are formed by 8 cysteines.With a general structural formula of C-Xn-C-Xn-CC-Xn-CXC-Xn-C-Xn-C,LTPs usually have a N-terminal signal peptide in their structure,these signal peptides can locate and guide proteins to the apoplast space of the cell.At present,LTP7 in lipid transfer proteins family has not been intensively studied.In this experiment,Arabidopsis thaliana mutant Atltp7 was used as the experimental material to explore the role of LTP7 in the growth,development and the epigenetic differences that occur when the LTP7 gene expression is down-regulated in Arabidopsis.The main results are as follows:1.LTP7 has the structural characteristics of typical LTPs.Based on bioinformatics prediction of the amino acid sequence,the secondary and tertiary structures of LTP7 were analyzed.The secondary structure showed that LTP7 conformed to the basic structure of C-Xn-C-Xn-CC-Xn-CXC-Xn-C-Xn-C for lipid transfer proteins,and its tertiary structure had a penetrating hydrophobic cavity,which could bind and transfer lipids through its hydrophobic port.2.The ltp7 mutant differs from the wild-type in the reproductive growth phenotype.Detecting the tissue-specific expression of LTP7 in the wild-type,and the results showed that LTP7 was the highest expressed in Arabidopsis stalks.It was found that the ltp7 mutant had an average bolting time 2-3 days earlier than the wild-type.The average length of the mutant stem from bolting to maturity was longer than that of the wild-type.The difference in LTP7 gene expression may be the cause of the difference in bolting time between the mutant and the wild type.3.There were differences in fatty acid content between ltp7 mutant and the wild-type seeds.LTP7 has the function of transfering lipids in the cell.GC-MS detected the content of the main components of fatty acids in the ltp7-1 mutant and the wild-type,and found that the palmitic acid,oleic acid,eicosenoic acid,linolenic acid and erucic acid are higher than those of the wild-type,but the 1000-kernel weight showed no difference between the mutant and the wild-type,which proves that LTP7 is involved in the accumulation and transformation of fatty acid components at the seed development stage in Arabidopsis.4.The germination rate of ltp7 mutant seeds was reduced under salt stress.Salt stress was applied to seeds to observe the difference in germination rate between the ltp7-1 mutant and the wild-type under different NaCl concentrations.The results showed that the germination rate of ltp7-1 mutant under 150 mmol / L NaCl treatment was significantly lower than that of the wild-type seeds,and under the condition of no salt stress,the germination rate of the two is the same and normal.It is speculated that the reason is related to the difference in fatty acid content.5.LTP7 gene was transformed into ltp7 mutant,the mutant phenotype was recovered in the transfromant plants.Through the construction of the expression vector p CAMBIA1300-LTP7 of LTP7 gene,and using inflorescence infestation method,the reversion expression vector was tranfered into ltp7-1 mutant.The resistant plants were successfully obtained after resistance screening.The transfromant plants laid the foundation for the subsequent molecular mechanism research.