Responses to salt and cold stresses of the hybrid ‘Yannong Hongxue’× ‘Yannong Chenghuang’ and its parent species

• Hybrid offspring have larger flowers and leaves than their parent plants. • Hybrid offspring are more salt-tolerant than the male plant. • The salt tolerance of the hybrid offspring is higher than that of the male plant. Abiotic stressors such as low temperature and salt stress severely compromise the growth, development, and geographical distribution of chrysanthemums, markedly limiting their application in landscape architecture. Consequently, the cultivation of ground-covering chrysanthemum varieties with both high ornamental value and certain resistance properties has become an important goal in chrysanthemum breeding. We obtained the hybrid offspring through crossbreeding. The leaf length, width, inflorescence diameter, and tubular flower length of the hybrid progenies were 4.37 cm, 3.35 cm, 4.63 cm and 2.27 cm, respectively, which were higher than the medium parent values. The proportion of polymorphic loci in the hybrids, as detected by SRAP markers, ranged from 66.67 % to 100 %. Under salt stress and low-temperature conditions, the activities of peroxidase, superoxide dismutase, catalase, and proline content, were significantly higher in the paternal “Yannong Chenghuang” and hybrid species than in the maternal species. Concurrently, we evaluated the expression levels of the relevant genes. When exposed to 200 mM NaCl, the expression levels of CmSOS1, CmSOS2, CmSOS3 and CmHKT in the hybrid offspring were 1.52, 2.4, 2.28 and 1.44 times higher than those in “Yannong Hongxue”, respectively. The expression levels of cold tolerance-related genes, namely, CmICE, CmCBF1 , and CmLEA , in the hybrids exhibited an increase of 1.1-fold, 1.41-fold, and 1.74-fold, respectively, compared with those in “Yannong Hongxue”. The findings revealed that the hybrid progenies exhibited increased inflorescence diameter and leaf size compared with their paternal parents. Moreover, the hybrids exhibited superior salt and cold tolerance compared with their maternal parents.