In vitro induced tetraploid of Dendranthema nankingense (Nakai) Tzvel. shows an improved level of abiotic stress tolerance

The tetraploid of Dendranthema nankingense (Nakai) Tzvel. was induced by the colchicine treatment using nodal segments. Ploidy level was determined by an analysis of flow cytometry and chromosome counting. The morphological characteristics such as the stomata, leaves, flowers and pollen grains of the tetraploid were significantly larger than those of the diploid. The tolerance responses of the diploid and tetraploid were compared under the imposition of heat, cold, drought and salinity stress. Semi-lethal temperatures suggest that cold tolerance is improved by polyploidization, but the heat tolerance is reduced. Under drought and salt stress, the activity of peroxidase (POD) and relative water content (RWC) in the tetraploid were higher than those in the diploid. Accordingly its malondialdehyde (MDA) content maintained a lower level. The content of chlorophyll (a + b) in the tetraploid was higher, and decrease of its content was postponed in tetraploid compared with the diploid under salt stress. It suggested that polyploidization could alleviate oxidative stress, maintain good water balance and higher chlorophyll (a + b) content, thereby enhanced the drought and salt tolerance in colchicine induced tetraploid.

Research highlights▶ The tetraploid of Dendranthema nankingense (Nakai) Tzvel. was induced by colchicines. ▶ Stomata, leaves, flowers and pollen grains of the tetraploid were larger. ▶ Tetraploid showed better cold, drought and salt tolerance, but worse heat tolerance. ▶ Polyploidization could alleviate oxidative stress. ▶ Tetraploid maintained good water balance and higher chlorophyll (a + b) content.