Induced Mutations for Plant Breeding·Agricultural Biotechnology
WANG Zhilan, TANG Chuchu, XIA Meilin, DU Xiaofen, LIAN Shichao, LI Yuxin, HAN Kangni, WANG Jun
Salt stress is one of the key abiotic constraints limiting crop growth and productivity. To screen salt-tolerant and salt-sensitive mutants from a foxtail millet (Changnong 35) ethyl methanesulfonate (EMS) mutant library, the salt tolerance of 489 mutants under 180 mmol·L-1 NaCl treatment during the germination stage were evaluated. Six parameters including relative germination potential (RGP), relative germination rate (RGR), relative root length (RRL), relative bud length (RBL), relative salt damage rate (RSDR), and relative root-to-bud ratio (RRSR) were analyzed. Comprehensive multivariate analysis methods, including principal component analysis (PCA), correlation analysis, membership function method, cluster analysis, were conducted for comprehensive salt tolerance assessment. The results indicated that there were extensive variations among the mutants, with the coefficient of variation ranging from 15.02% to 95.69%. The six relative indicators were correlated to varying degrees. Through principal component analysis, the six individual indicators were condensed into three comprehensive indicators, and the D value of the comprehensive evaluation index was calculated. Based on the D value, the 489 mutants were categorized into four groups: 70 salt-tolerant mutants, 235 moderately salt-tolerant mutants, 172 intermediate mutants, and 12 salt-sensitive mutants. Additionally, the salt tolerance indices and antioxidant enzyme activities of the salt-tolerant mutant E162 and the salt-sensitive mutant E219 at the germination stage were compared. The results showed that the germination rate, shoot length, and root length of salt-tolerant mutant E162 were significantly higher than those of salt-sensitive mutant E219 after salt treatment. Furthermore, compared to the control (deionized water), the activities of CAT, POD, and SOD were significantly or highly significantly increased in the salt-tolerant mutant E162 under the treatment with 180 mmol·L-1 NaCl while no significant difference was observed for the salt-sensitive mutant E219. The results indicated that salt-tolerant mutants had enhanced antioxidative capacity to mitigate salt-induced oxidative damage. This study provides valuable genetic resources for elucidating salt tolerance mechanisms and improving salt tolerance in foxtail millet.