AUTHOR=Li Chunxin , Song Tingting , Zhan Lifeng , Cong Chunlong , Xu Huihui , Dong Li , Cai Hua 

TITLE=Overexpression of MsRCI2A, MsRCI2B, and MsRCI2C in Alfalfa (Medicago sativa L.) Provides Different Extents of Enhanced Alkali and Salt Tolerance Due to Functional Specialization of MsRCI2s

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.702195

DOI=10.3389/fpls.2021.702195

ISSN=1664-462X

ABSTRACT=<p>Rare cold-inducible 2/plasma membrane protein 3 (<italic>RCI2/PMP3</italic>) genes are ubiquitous in plants and belong to a multigene family whose members respond to a variety of abiotic stresses by regulating ion homeostasis and stabilizing membranes, thus preventing damage. In this study, the expression of <italic>MsRCI2A</italic>, <italic>MsRCI2B</italic>, and <italic>MsRCI2C</italic> under high-salinity, alkali and ABA treatments was analyzed. The results showed that the expression of <italic>MsRCI2A</italic>, <italic>MsRCI2B</italic>, and <italic>MsRCI2C</italic> in alfalfa (<italic>Medicago sativa</italic> L.) was induced by salt, alkali and ABA treatments, but there were differences between <italic>MsRCI2</italic> gene expression under different treatments. We investigated the functional differences in the MsRCI2A, MsRCI2B, and MsRCI2C proteins in alfalfa (<italic>Medicago sativa</italic> L.) by generating transgenic alfalfa plants that ectopically expressed these <italic>MsRCI2</italic>s under the control of the CaMV35S promoter. The <italic>MsRCI2A/B/C</italic>-overexpressing plants exhibited different degrees of improved phenotypes under high-salinity stress (200 mmol.L<sup>–1</sup> NaCl) and weak alkali stress (100 mmol.L<sup>–1</sup> NaHCO<sub>3</sub>, pH 8.5). Salinity stress had a more significant impact on alfalfa than alkali stress. Overexpression of <italic>MsRCI2</italic>s in alfalfa caused the same physiological response to salt stress. However, in response to alkali stress, the three proteins encoded by <italic>MsRCI2</italic>s exhibited functional differences, which were determined not only by their different expression regulation but also by the differences in their regulatory relationship with <italic>MsRCI2</italic>s or <italic>H<sup>+</sup>-ATPase</italic>.</p>