Preliminary Functional Analysis Of Arabidopsis Thaliana Serine Incorporate Protein,AtSERDl And AtSERD2

Biofilm phospholipids are an important component of biofilm lipid bilayers.Phospholipid molecules constitute the biofilm together with proteins,glycolipids,thioesters,sterols and other molecules.In plants,membrane phospholipids not only participate in the composition of biofilms,but act as signaling molecules when plants encounter stress.For example,under drought stress,Sphingolipid can act as a signaling molecule to participate in stomata closure.Ser(Serine)is the indispensable raw material of PS(Phosphatidyl Serine,PS),Sphingolipid and PC(Phosphatidyl Cholines,PC)which are the components of membrane phospholipids.As a scaffold for serine synthesis related enzymes and serine carrier protein,serine incorporator(SERINC)play an important role in the synthesis of phospholipids.The "family" of SERINC consists of five "family members",from SERINC 1 to SERINC 5.At present,there are a large number of studies in humans,indicating that SERINC5/SERINC3 can effectively inhibit the infection of Nef-deleted HIV-1 virus particles.However,very little research has been done on these proteins in plant.In order to investigate the biological function of SERINC proteins in plants,we selected AtSERD1(Arabidopsis thaliana SERINC-domain 1)and AtSERD2(Arabidopsis thaliana SERINC-domain 2)proteins from the SERINC protein family in Arabidopsis thaliana.Mutant phenotype screening was performed using molecular genetics method.And the functions of AtSERD1 and AtSERD2 were studied preliminarily by histochemical staining,subcellular localization,RT-PCR,drought culture,and observation of stomatal movement.The results obtained in this paper are as follows:(1)AtSERDl and AtSERD2 are expressed in guard cells.We infected the wild type Arabidopsis plants with Agrobacterium tumefaciens GV3101 which had been transferred the AtSERD1pro::GUS and AtSERD2pro::GUS fusion vectors to obtain positive plants.AtSERDl and AtSERD2 were found to express in guard cells by GUS staining.(2)AtSERD1 and AtSERD2 are located in the cytoplasm.We transiently expressed GFP-empty,3 5 S::AtSERD 1-GFP and 3 5 S::AtSERD2-GFP fusion expression vectors in protoplasts.We found the cellular location of AtSERD1 and AtSERD2 is the cytoplasm.(3)AtSERDl and AtSERD2 participate in the response to drought stress in plants.AtSERDl and AtSERD2 loss-of-function mutant plants serdl,serd2,serdl xserd2 were more sensitive to drought than wild-type plants.Water loss experiments in leaves showed that the water loss rate of serdl,serd2 and serdl xserd2 plants were higher than that of wild type plants.These results indicate that AtSERD1 and AtSERD2 play a positive regulatory role in drought response in plants.(4)AtSERD1 and AtSERD2 loss-of-function mutants are insensitive to ABA-induced stomatal closure.During light-induced stomatal opening,there was no difference between the mutants and the wild-type.After treatment of ABA,the stomatal aperture in mutants was larger than that of the wild type.The results showed that AtSERD1 and AtSERD2 loss-of-function mutants were insensitive to ABA-induced stomatal closure.(5)AtSERD1 and AtSERD2 loss-of-function mutants are sensitive to osmotic stress.Under high salt and hyperosmotic treatments,growth of mutant was more severely affected than wild type.We speculate that AtSERDl and AtSERD2 are involved in plant osmotic stress response.In summary,based on the analysis of the biological effects of SERINC proteins AtSERD1 and AtSERD2,we suggest that SERINC may involve in drought stress and osmotic stress response in plant.This provides a direction for future studies of the protein in plants.