Characteristic Analysis And Ion Absorption Dynamics Of Salt Tolerance Related Gene CaNAC36 In Pepper

Salt stress is a common phenomenon in horticultural crop production.In order to understand the physiological response changes and sensitivity differences of different salt tolerant pepper materials under salt stress,this study treated pepper materials with Na Cl salt solution（extremely salt tolerant PI201224 and extremely sensitive PI438643）to quantitatively measure the changes of ion content in different tissues and organs;At the same time,the gene CaNAC36 related to salt tolerance in its genome was cloned and its expression under stress was analyzed.The results provide a theoretical basis for clarifying the molecular mechanism of salt tolerance in pepper.The main results are as follows:（1）In order to explore the physiological response and sensitivity differences of pepper material types to salt stress,100 mmol×L^-1Na Cl solution was treated at seedling stage.The contents of calcium,potassium,sodium and chlorine in different tissues and organs were measured by colorimetry and turbidimetry.The results showed that the Ca²⁺accumulation in leaves and stems of pepper material PI201224was more,and the Ca²⁺accumulation in leaves and stems for 1h and 12h was 145.1%and 107.4%of that in the control group,respectively;By analyzing the K⁺/Na⁺values in different parts of the two plants,it was found that the Na⁺content in the roots of pi201224 was significantly higher than that in the leaves,and the root intercepted part of Na⁺to reduce the Na⁺content in the leaves.In addition,the K⁺content in the roots decreased,but increased the ability to transport K⁺to the leaves,so as to increase the K⁺content and K⁺/Na⁺value of the leaves,while the Na⁺accumulation ability of PI438643 was lower than that of PI201224;In addition,Cl^-accumulation in leaves,stems and roots of PI201224 was more than that of PI438643.（2）Based on the previously identified transcription factor CaNAC36 related to salt stress response in pepper,the functional annotation of 48 related genes was carried out.It was found that 14 genes belong to functional proteins such as transmembrane protein,transporter,aquaporin,chloride channel protein and detoxification protein.Fluorescence quantitative expression analysis showed that CaNAC36 was induced up and down regulated in the root tissues of salt tolerant and salt sensitive materials,and five associated genes（Capana08g002748、Capana00g004514、Capana09g000275、Capana07g001450、Capana02g001031）were significantly differentially expressed in different treatment periods and tissues of salt tolerant and salt sensitive materials.CaNAC36 and five associated gene promoter domains contain a large number of stress-related cis acting elements.The results show that CaNAC36 transcription factor may play an important role in regulating the salt tolerance mechanism of Pepper by interacting with the above five related genes.（3）The full-length DNA and c DNA sequence of CaNAC36 gene were cloned and amplified from pepper material PI201224.Bioinformatics analysis showed that the total length of CaNAC36 gene DNA was 3700bp,the length of c DNA complete open reading frame（ORF）was 1899bp,and the gene contained an open reading frame encoding 753 amino acids.Amino acid sequence alignment and homology analysis showed that the CaNAC36 gene of pepper was closest to Capsicum annuum（XM-016708691.1）,Capsicum annuum（XM-016708692.1）,tomato Solanum lycopersicum（XM-026029789.1）and Potato Solanum tuberosum（XM-006347254.2）,and the homology reached 100.00%,99.53%,86.79%and 85.08%respectively.The homology comparison and phylogenetic tree analysis between CaNAC36 and NAC family members in different plants show that CaNAC36 belongs to tip subfamily in the first family of NAC family.Real time fluorescence quantitative analysis showed that high salt could induce the expression of CaNAC36 gene in roots,stems and leaves of different salt tolerant materials,and the expression in salt tolerant materials was higher than that in salt sensitive materials.