Proline Biosynthesis Enzyme Genes Confer Salt Tolerance to Switchgrass (Panicum virgatum L.) in Cooperation With Polyamines Metabolism

Abstract

Understanding the regulation of proline metabolism necessitates the suppression of two D 1-pyrroline-5-carboxylate synthetase enzyme (P5CS) genes performed in switchgrass (Panicum virgatum L.). The results reveal that overexpressing PvP5CS1 and PvP5CS2 increased salt tolerance. Additionally, transcript levels of spermidine (Spd) and spermine (Spm) synthesis and metabolism related genes were upregulated in PvP5CS OEtransgenic plants and downregulated in the PvP5CS RNAi transformants. According to salt stress assay and the measurement of transcript levels of Polyamines (PAs) metabolism-related genes, P5CS enzyme may not only be the key regulator of proline biosynthesis in switchgrass, but it may also indirectly affect the entire subset of pathway for ornithine to proline or to putrescine (Put). Furthermore, application of proline prompted expression levels of Spd and Spm synthesis and metabolism-related genes in both PvP5CS-RNAi and WT plants, but transcript levels were even lower in PvP5CS-RNAi compared to WT plants under salt stress condition. These results suggested that exogenous proline could accelerate polyamines metabolisms under salt stress. Nevertheless, the enzymes involved in this process and the potential functions remain poorly understood. Thus, the aim of this study is to reveal how proline functions with PAs metabolism under salt stress in switchgrass.

Characterization of Differentially Expressed Genes under Salt Stress in Olive

“…Over-expression of OeP5CS gene at 210 DATS in both tolerant and moderately tolerant Royal and Koroneiki cultivars, highlighted this gene as one of the most solid candidates regulating salt tolerance. Our results confirmed what was previously observed in Panicum virgatum by Guan et al [ 65 ]. Moreover, the regulatory elements detection in upstream/downstream parts of this gene did not show any differences among the four analyzed genomes, highlighting the strong conservation of UTRs regions.…”

“…P5CS gene expression is directly related to salt stress and ABA function in O. sativa [ 63 , 64 , 65 ]. P5CS gene expression level and the proline content increased in Lepidium draba with increasing concentrations of NaCl [ 63 ], and P5CS1 and P5CS2 increased salt tolerance in Panicum virgatum [ 64 ].…”

“…Moreover, several studies have demonstrated that over-expression of P5CS gene increases proline production and confers salt tolerance on transgenic plants [ 46 ]. For this reason, it is conceivable that P5CS and proline synthesis are involved in regulation of Na + accumulation in leaves and, consequently, in salt stress tolerance [ 65 ].…”

Endophytic Fungi Controls the Physicochemical Status of Maize Crop under Salt Stress

“…Similarly, Azotobacter chrocoocum (A101) as a plant growth promoting rhizobacteria (PGPR) controlled proline contents, water uptake, photosynthetic efficiency and water use efficiency in the basil plants subjected to stress [47]. Proline accumulation in plants can be normalized through down or up-regulation of the enzyme that are responsible for the degradation or biosynthesis of proline [48]. So it might be possible that plant-microbe interation regulates the proline production by controlling the expression of proline metabolizing enzymes.…”

Halotropism: Phytohormonal Aspects and Potential Applications

“…Newest findings suggest that PAs can adjust the quality control of post-transcriptional regulation ( Poidevin et al., 2019 ). Some important N-containing metabolite like proline amino acid ( Szepesi and Szollosi, 2018 ; Guan et al., 2020 ) or gamma-aminobutyric acid (GABA) as endproduct of PA catabolism could be involved in abiotic stress responses ( Su et al., 2019 ). PA catabolism can synthesize secondary messengers like hydrogen peroxide or GABA ( Wang W. et al., 2019 ), involved in sublethal and lethal salt stress ( Takács et al., 2017 ).…”