Study On The Mechanism Of Salt Exclusion In The Roots Of Suaeda Salsa In Different Habitats

Suaeda salsa(S.salsa)can occur both on inland saline soils and intertidal zone,and the saline condition in the two habitats is different.The aim of the current study is to understand the molecular and physiological mechanisms related to salt tolerance in two S.salsa populations from different saline environments.The results are as follows: 1.The role of transporters and channel in salt exclusion of the roots in S.salsaSalinity(300 m M NaCl)significantly increase the content of Na~+ and Cl~-in the roots,leaves and xylem sap of the two S.salsa populations from different saline environments.At 300 m M NaCl,the roots of the intertidal population accumulated more Na~+ and Cl~-compared with those in the inland population,but an opposite trend was observed in the leaves.Compared to the inland population,the intertidal population accumulated less Na~+ and Cl~-in the xylem sap,i.e.,the Na~+ and Cl~-content in the xylem sap of the intertidal population was 79.4 and 86.9% of that in the inland population,respectively.Non-invasive Micro-test Technology(NMT)analysis revealed that the intertidal population exhibited a higher capacity to extrude Na~+ at 300 m M NaCl,compared to the inland population,and the efflux of Cl~-in the roots of the intertidal population was slightly elevated compared to that in the inland population at 300 m M NaCl.At 300 m M NaCl,the efflux of Cl~-was higher than Na~+ in the roots of the two S.salsa populations from different saline environments.Salinity significantly increased the relative expression of SsSOS1,SsNHX1 and SsCLCc in the roots in both populations.The relative expression of SsSOS1,SsNHX1 and SsCLCc in the roots of intertidal population was higher than those in the inland population,especially at 300 m M NaCl.In conclusion,roots of the intertidal population had a higher capacity of Na~+ and Cl~-exclusion than roots of the inland population,and SsSOS1,SsNHX1 and SsCLCc may be related to this process.These characteristics may explain why the intertidal population of S.salsa can abidingly thrive in high saline environments.2.The clone of Cl~-channel protein gene SsCLCc in S.salsaThe primers of middle fragment were designed based on the sequence of CLCc(2460 bp)which was related to Cl~-channel protein which was produced by the transcriptome sequence of S.salsa,and to amplify specific DNA fragment using c DNA prepared from S.salsa roots by PCR.The middle fragment was blasted on NCBI and the blast results on the NCBI are as follows: The middle fragment was similar to the homologous genes of Beta vulgaris subsp.Vulgaris and Glycine max,and the homology was 84% and 71%,respectively.This indicates that the fragment is likely to be the middle fragment of S.salsa CLCc(temporarily named as SsCLCc).The 5' and 3' fragment of the gene was obtained by 5' and 3' RACE.The full length sequence of SsCLCc was 2418 bp,and 3' RACE and 5' RACE fragment was 879 bp and 842 bp,respectively.The c DNA sequence of SsCLCc was 1881 bp.The c DNA sequence of SsCLCc was blasted on NCBI and the blast results on the NCBI are as follows: The sequence was similar to the homologous genes of Beta vulgaris subsp.Vulgaris and Morus notabilis,i.e.,the homology was 84% and 75%,respectively.Therefore,the cloned sequence was preliminarily confirmed as the gene of Cl~-channel protein in S.salsa.The function of the gene will be verified in future work.