Analysis of Amino Acids in the Roots of Tamarix ramosissima by Application of Exogenous Potassium (K+) under NaCl Stress

Abstract

Soil salinization is one of the main environmental factors affecting plant growth worldwide. Tamarix ramosissima Ledeb. (T. ramosissima) is a halophyte representative that is widely grown in salinized soils. As an important nutrient element for plant growth, K+ plays an important role in improving the tolerance to salt stress, but the mechanism of reducing the damage caused by NaCl stress to T. ramosissima is less reported. Our results show that the proline content and the Log2 fold-change of proline’s relative quantification in the roots of T. ramosissima increased over time with the application of exogenous potassium (K+) for 48 h and 168 h under NaCl stress. Moreover, 13 amino-acid-related metabolic pathways were involved in the resistance of T. ramosissima to salt stress. Mainly, the aldehyde dehydrogenase family genes and tryptophan-synthase-related genes were found at 48 h and 168 h with exogenous potassium applied to the roots of T. ramosissima under NaCl stress, and they regulated their related metabolic accumulation in the arginine and proline metabolism pathways, increasing the effectiveness of inducing NaCl tolerance of T. ramosissima. It is noteworthy that alpha-ketobutyric was produced in the roots of T. ramosissima under NaCl stress for 48 h with the application of exogenous potassium, which is one of the most effective mechanisms for inducing salt tolerance in plants. Meanwhile, we found three DEGs regulating alpha-ketobutyric acid. This study provides a scientific theoretical basis for further understanding the molecular mechanism of K+ alleviating the salinity damage to T. ramosissima caused by NaCl.

Effects of Exogenous (K+) Potassium Application on Plant Hormones in the Roots of Tamarix ramosissima under NaCl Stress

“…To verify the reliability of transcriptome sequencing data, we randomly selected 7 key DEGs for qRT-PCR verification using Chen et al [ 54 ]. According to these validation results, qRT-PCR results were completely consistent with transcriptome sequencing analysis results ( Figure 5 ), proving that the transcriptome data are accurate and reliable.…”

“…We submitted the raw data obtained by transcriptome sequencing to the National Center for Biotechnology Information (NCBI) Short Reads Archive (SRA) database (SRP Number: SRP356215). Transcriptome data were analyzed and differentially expressed genes were screened according to the method of Chen et al [ 40 , 54 ].…”

“…However, as a halophyte, T. ramosissima has the ability to retain more K + under salt stress conditions to adapt to different saline-alkali conditions [ 52 ]. It has been reported that the application of 10 Mm KCl under the stress of 200 mM NaCl can increase the activities of SOD, POD and CAT in leaves of T. ramosissima [ 53 ], and K + transporter, K + channel and amino acid-related genes in T. ramosissima root are up-regulated and related genes are involved in resisting NaCl stress and maintaining the growth of T. ramosissima [ 40 , 54 ]. In this study, T. ramosissima was taken as the research object, and the important metabolic pathways and key differentially expressed genes (DEGs) related to plant hormones in response to NaCl stress were excavated from the transcriptome level by exogenous potassium application.…”

Analysis of the Antioxidant Mechanism of Tamarix ramosissima Roots under NaCl Stress Based on Physiology, Transcriptomic and Metabolomic

“…Then, we submitted the raw sequencing data obtained by transcriptome sequencing to the Short Reads Archive (SRA) database of the National Center for Biotechnology Information (NCBI), SRP number SRP356215. Finally, we referred to the method of Chen et al to screen the differentially expressed genes (DEGs) from the sequencing data [ 46 ], and the DEGs were obtained for Gene Ontology (GO) [ 47 ] and Kyoto Encyclopedia of Genes and Genomes (KEGG) [ 48 ] enrichment analysis.…”

“…ramosissima root after experimental treatment to GENE Denovo biotechnology company (GENE Denovo, Guangzhou, China) for metabolite extraction and detection and then analyzed via liquid chromatography–mass spectrometry (LC–MS) [ 49 ]. We referred to the method of Chen et al for differential metabolite screening and p -value testing of sequencing data [ 46 ]. At the same time, we also identified the pathways annotated by differential metabolites in the KEGG database ( , accessed on 22 January 2021).…”