Physiological response to salt tolerance of a waxy mutant of Dianthus spiculifolius

Salt stress can cause osmotic stress and ion toxicity, leading to cell dehydration, inhibition of photosynthesis and respiration, and further effects on the growth and development of plants. Plant cuticular wax can prevent non-stomatal water loss from leaves, reduce transpiration, and slow down physiological drought caused by stress. In this study, the wild-type (WT) and a mutant with increased cuticular wax (WM) of Dianthus spiculifolius ornamental ground-cover species were used, and their phenotypic, physiological, and biochemical indicators under NaCl stress were compared. The results showed that, under NaCl stress, the waxy mutant showed a more salt-tolerant phenotype resulting from its higher water content. In addition, the waxy mutant showed higher peroxidase (POD) and catalase (CAT) activity, soluble sugar content, proline content, photosynthetic capacity, and lower malondialdehyde (MDA) content under NaCl stress. Dewaxing experiments showed that the difference in relative water content and water retention between the waxy mutant and the wild-type under NaCl stress was directly related to cuticular wax. These results suggest that cuticular wax plays an important role in the plant’s response to salt stress.