Induction and Characterization of Tetraploids from Astragalus membranaceus (Fisch.) Bge. Seeds

Astragalus membranaceus (Fisch.) Bge., as a Traditional Chinese medicine, not only has ornamental and medicinal value but also plays a role in the effect of sand fixation. At present, the resources of wild A. membranaceus are exhausted with the deterioration of the ecological environment and the increase in market demand. Moreover, there are no excellent varieties for the artificial cultivation of A. membranaceus to meet the market demand. To establish a method to create an efficient induction of tetraploids by colchicine technique in A. membranaceus. The germinating seeds were soaked in different concentrations of colchicine solution and exposure times to induce tetraploids in A. membranaceus, and the induced plants were identified by morphological characteristics comparison and root-tip chromosome determination. The contents of polysaccharides, saponins, and flavonoids and the activity of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were measured in diploid and tetraploid plants. The results showed that the highest tetraploid induction ratio of germinating seeds in A. membranaceus is obtained from the 0.2% (w/v) colchicine treatment for 36 h, and the chromosome number of tetraploid seedlings was 2n = 4x = 32. The morphological traits and anatomical structure characteristics of leaves from tetraploid plants exhibited significant differences from the diploid plants. The contents of polysaccharides, saponins, and flavonoids and the activity of SOD, POD, and CAT are also increased in tetraploid plants. In summary, our study provided an effective method to induce A. membranaceus polyploidy, which could be used to develop new germplasm innovations for improving the medicinal value of A. membranaceus.