Interspecific hybrids between Chrysanthemum grandiflorum (Ramat.) Kitamura and C. indicum (L.) Des Moul. and their drought tolerance evaluation

Chrysanthemum grandiflorum 'Yuhuaxingchen' is an important commercial chrysanthemum cultivar with excellent ornamental quality but low drought tolerance, whereas C. indicum has exceptional drought tolerance. In our earlier study, many hybrid seeds between them were obtained through interspecific hybridization. In the present study, we selected six putative hybrid lines with most drought tolerance from all the hybrid lines by withholding water, indentified their facticity by chromosome counting, and then evaluated their drought tolerance through determining foliar electrolyte leakage (EL), contents of malondialdehyde (MDA) and proline, and plant survival rate after 20% polyethylene glycol 6000 treatment. It was found that 155 out of 282 seeds germinated and only 132 seedlings survived. In addition, chromosome and morphological analysis showed that the six putative hybrids were real hybrids and their morphological features were intermediate between their parents. Furthermore, the density of leaf epidermal hair, proline content, and plant survival rate were the highest in C. indicum and the lowest in C. grandiflorum among the six hybrids and their parents. In contrast, EL value and MDA content were the highest in C. grandiflorum and the lowest in C. indicum. These results suggest that some true hybrids with improved drought tolerance can be obtained through interspecific hybridization in chrysanthemum breeding. Therefore, interspecific hybridization between chrysanthemum cultivars and their wild species may become a promising way to improve their biotic and abiotic resistance in the future breeding.