AUTHOR=Guan Cong , Cui Xin , Liu Hua-yue , Li Xue , Li Meng-qi , Zhang  Yun-wei 

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

JOURNAL=Frontiers in Plant Science

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.00046

DOI=10.3389/fpls.2020.00046

ISSN=1664-462X

ABSTRACT=<p>Understanding the regulation of proline metabolism necessitates the suppression of two <italic>Δ<sub>1</sub>-pyrroline-5-carboxylate</italic> synthetase enzyme (<italic>P5CS</italic>) genes performed in switchgrass (<italic>Panicum virgatum</italic> L.). The results reveal that overexpressing <italic>PvP5CS1</italic> and <italic>PvP5CS2</italic> increased salt tolerance. Additionally, transcript levels of spermidine (Spd) and spermine (Spm) synthesis and metabolism related genes were upregulated in <italic>PvP5CS OE</italic>-transgenic plants and downregulated in the <italic>PvP5CS RNAi</italic> transformants. According to salt stress assay and the measurement of transcript levels of Polyamines (PAs) metabolism-related genes, <italic>P5CS</italic> 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 <italic>PvP5CS</italic>-<italic>RNAi</italic> and WT plants, but transcript levels were even lower in <italic>PvP5CS</italic>-<italic>RNAi</italic> 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.</p>