Genetic Variation in Salt Stress Response and Germplasm Resource Evaluation among <i>Lycium</i>Accessions

Genetic variation between naturally occurring ecotypes can be helpful to elucidate the mechanism controlling salt stress response in different environments. The salt stress response of 20 natural accessions or cultivars of Lycium was characterized at a physiological level, following exposed to 300 mM NaCl for 15 days. It is shown that salt stress increased Na+, betaine and malondialdehyde (MDA) content, as well as the relative permeability of plasma membranes, but decreased K+, chlorophyll and glutathione (GSH) content, as well as K+/Na+ ratio compared with their respective control value in most of the varieties, though the increasing or decreasing extent has a clear genetic diversity. The physiological response was utilized to evaluate the salt-tolerant capacity of these varieties by principal component analysis and clustering analysis, and in which total chlorophyll, K+/Na+ ratio and partially GSH have the maximum weight relatively. These varieties could be categorized into four sub-groups, means greatly resistance (Heiguo, Ninqi No. 2 and Beifang), moderately resistant, sensitive, and mostly sensitive (Ninqi No. 7) to salt stress. Our results provide a theoretical basis and practical guidance for the improvement of saline-alkali land and rational utilization of Lycium germplasm resources in the future.