Induction and characterization of tetraploid pear from the seeds of 'Dangshansuli' (Pyrus bretschneideri Rehd.)

Pear is one of the most economically important fruit crops widely distributed around the world. To enrich the pear germplasm resources for obtaining the polyploid plants, the seeds from pear cultivar of 'Dangshansuli' (Pyrus bretschneideri) were treated with colchicine solution under concentration gradients of 0.1%, 0.5% and 1.0% for 12-, 24- and 48-h, respectively. Our results showed that colchicine could inhibit seed germination, and the inhibitory effect was positive with the treated concentration of colchicine. We detected that the 0.1% colchicine solution for 12 h was the most effective treatment for inducing pear polyploidy. Furthermore, compared with the wild diploid pear plants, a significant morphological variation, such as shorter plants, smaller and oval leaves were observed in the induced tetraploid pear plants. Significant changes in leaf anatomy, including larger and sparse stomata and the epidermal cells with irregularly or polygonal-shape were also detected in tetraploid pear plants. In addition, the contents of 10 cuticular wax compounds from the leaves of diploid and tetraploid pear plants were also detected with significant difference. Taken together, this study lays the foundation for polyploid breeding of pear for contributing diverse characteristics.