Successful induction and the systematic characterization of tetraploids in cerasus humilis for subsequent breeding

The Chinese dwarf cherry (Cerasus humilis; 2n = 16) has been increasingly prized for its colorful fruits, high economic values, nutraceutical benefits, and wide adaptability for diverse soil and environmental conditions. Polyploid induction is an efficient way to develop new selections and cultivars of horticultural crops. In this study, successful induction of tetraploids (2n = 32) in C. humilis (cultivar: ‘Nongda 7’) was achieved and the tetraploid plants were subsequently characterized. The highest mutagenesis rate reached in our study was 30.0 % with 80 mg/L colchicine added to the solid Murashige and Skoog (MS) media for both the embryo and stem tip. In liquid media, the highest mutagenesis rate achieved was 16.7 % with the addition of 60 mg/L colchicine. Systematic examination of the induced tetraploid mutants, significant morphological differences were observed in leaves, stems, and roots. Tetraploid mutants exhibited larger leaves, shorter internodes, and thicker roots than their diploid counterparts. Moreover, average stomatal size of the tetraploid mutants was significantly larger than that of the diploids. At the same time, the stomatal density of tetraploid plants decreased significantly in comparison to the that of diploids. The tetraploid mutants have been and will be used in our breeding efforts of new cultivars with higher yields, better fruit quality and wider adaptability.