Morphological and physiological responses of Dianthus spiculifolius high wax mutant to low-temperature stress

Cuticular wax plays a role in plant responses to environmental stresses. To understand the contribution of cuticular wax to plant responses to low-temperature stress, the morphological and physiological responses of a Dianthus spiculifolius high-wax (HW) mutant and wild type (WT) were compared. Under low-temperature stress (0 and −10 °C), HW plants showed a lower mortality rate and electrolyte leakage (El) than that WT plants. In plants treated with low-temperature stress (0 and −10 °C), HW mutant leaves exhibited higher soluble sugar and free proline contents and lower malondialdehyde contents than those WT leaves. The photosynthetic capacity, net photosynthetic rate, stomatal conductance, and maximal photochemical efficiency of photosystem II in HW mutant leaves were the least inhibited by low temperature than those in WT leaves. The dewaxing experiments showed no significant difference in the phenotype and El between the dewaxed-treated HW mutant and WT leaves under low-temperatures stress, indicating that cuticular wax causes differences in resistance to low-temperatures between HW and WT. Principal component analysis and the membership function value of the physiological data showed that the average membership value of the HW mutant was greater than that in WT. In general, the results indicated that high cuticular wax contributes positively to the response to low-temperature stress by D. spiculifolius.