Analysis Of Salt Tolerance Function Of ThASR4 Gene From Tamarix Hispida

Abscisic acid-,stress-,and ripening-induced proteins（ASR）are a class of small-molecular-weight proteins containing（ABA/WDS）domains in plants.ASR has transcription factors and LEA proteins It plays an important role in plant stress response and fruit ripening.In this study,an ASR gene possibly related to salt stress response was identified from the transcriptome data of Tamarix hispida,named ThASR4.The length of the open reading frame（ORF）of this gene is 687 bp,it can encode 228 amino acids,its relative molecular mass is24.45k Da,and its theoretical isoelectric point（p I）is 5.33.The subcellular localization results revealed that ThASR4 protein was localized in the cytoplasm and nucleus.The real-time quantitative PCR results of ThASR4 gene upregulated expression induced by high salt revealed that ThASR4 may be involved in the response of Tamarix hispida to salt stress.The ThASR4 gene overexpression vector p ROKII-ThASR4 was constructed and transformed into Arabidopsis thaliana to obtain a T₃generation transgenic line.The wild-type and transgenic Arabidopsis thaliana were treated with Na Cl stress.Under the stress conditions,the germination rate,root length,fresh weight and growth of the transgenic line were superior to those of the wild-type line,indicating that ThASR4 was heterologously overexpressed in Arabidopsis thaliana.Genes can effectively improve its salt tolerance.The RNAi inhibitory expression vector p FGC5941-ThASR4 was constructed,and p ROKII-ThASR4 and p FGC5941-ThASR4 were transformed into Tamarix hispida by transient transformation technology.Together,the p ROKII vector plasmid was used to transiently infect Tamarix hispida as a control to obtain overexpression（OE）and inhibited expression（RNAi）,respectively.and control（Control,Con）-3 transiently transformed Tamarix hispida plants.Under salt stress,DAB,NBT and Evans blue staining of OE plants among the three transgenic tamarind species were the lightest,the MDA content,H₂O₂content and electrolyte permeability were the lowest,while POD and SOD enzyme activities and proline content were the highest;on the contrary,RNAi The DAB,NBT and Evans blue staining of the plants were the deepest,and the MDA content,H₂O₂content and electrolyte permeability were the highest,while POD and SOD enzyme activities and proline content were the lowest.At the same time,performed histochemical staining and determination of physiological indicators for ThASR4overexpression and wild-type Arabidopsis thaliana after salt stress treatment,and obtained similar experimental results to those in Tamarix hispida.Based on the above research results,the ThASR4 gene can increase the activity of antioxidant enzymes and the content of osmotic regulators,reduce the accumulation a lot of ROS induced by salt stress,and reduce the degree of cell membrane damage,thus enhancing the salt resistance of transgenic plants.