Physiological Characteristics and Strategies to Improve Salt Tolerance in Alfalfa

Non-Peer ReviewedThere are 6 million ha of cropland affected by soil salinity in Canada. Alfalfa is not only an important forage legume to the Canadian beef and forage industries, but also is the candidate legume for reclamation of saline areas. We investigated physiological and genetic variations of salt tolerant ‘Halo’ and salt intolerant ‘Vernal’ alfalfa cultivars in five gradients of salt stresses (Electrical conductivities of 0 dS m-1- 16 dS m-1) in a sand based hydroponic system. Elements and organic compounds in different tissues were studied at the Canadian Light Source. RNA-Seq analysis of leaf and root tissues of ‘Halo’ and ‘Vernal’ alfalfa were studied at three time points after salt treatment at 12 dS m-1. ‘Halo’ showed significantly greater germination percentage and seed vigor than ‘Vernal’ at higher salt level, but no difference was found at lower salt gradients. The leaf and stem tissue of ‘Halo’ had higher amide concentration than ‘Vernal’ at all salt gradients. This study identified 14 (leaf) and 9 (root) candidate genes consistently expressed in ‘Halo’ under salt stress, indicating potential genes for marker development. In addition, a number of new salt tolerant breeding lines were developed under this project. Future research includes testing of possible beneficial interactions between alfalfa populations and halophile bacteria that could help mitigate salt stress on the plant. Link to Video Presentation: https://youtu.be/QGpr13PKGg