Evaluation of Salinity Tolerance and Genetic Diversity of Thirty-Three Switchgrass (Panicum virgatum) Populations

Switchgrass (Panicum virgatum) is a warm-season C4 grass that is a target lignocellulosic biofuel species. Salt stress is one of the major limiting factors for switchgrass growth in many regions. The objective of this study was to examine relative salt tolerance and genetic diversity among 33 switchgrass populations. Seeds of each population were planted in cone-tainers and grown in a greenhouse. Two months after establishment, the switchgrass were grown in half strength Hoagland’s nutrient solution with either 0 mM NaCl (control) or half strength Hoagland’s nutrient solution with 250 mM NaCl (salt stress treatment) for 24 days. Salt stress tolerance was determined based on a variety of parameters including leaf electrolyte leakage (EL), chlorophyll content (Chl content), leaf photochemical efficiency (F v/F m), photosynthetic rate (P n), stomatal conductance (g s), and transpiration rate (T r). Significant differences in salt stress tolerance were found among the 33 populations. Based on the P n and salt tolerance trait index (STTI), lowland populations AM-314/MS-155, Kanlow, TEM-LoDorm, Alamo, and BN-13645-64, as well as upland populations T-2086, T-2101, BN-11357-63, and BN-12323-69 were classified as salt tolerant. In contrast, upland populations BN-18757-67, 70SG0021, Summer, 70SG0016, T16971, Dacotah, Turkey, 70SG003, and Pathfinder were classified as salt sensitive populations. Sequence-related amplified polymorphism (SRAP) marker analysis was employed to determine the genetic diversity among the 33 switchgrass populations. UPGMA cluster analysis showed that salt tolerant switchgrass populations TEM-LoDorm, Alamo, Kanlow, BN-12323-69, AM-314/MS-155, T2101, BN-11357-63, T-2086, and BN-13645-64 clustered into one group, indicating that these salt tolerant populations may have a similar genetic background.