Induction and ploidy identification of autotetraploid black wax gourd

Objective  To explore efficient induction method of autotetraploid Benincasa hispida and seek a simple, convenient, large flux and accurate method of ploidy level identification.

Method  The seedlings of diploid B. hispida inbred lines were used as materials. Autotetraploid B. hispida was induced using different concentrations of colchicine and oryzalin at different times including 06:00 to 07:00, 12:00 to 13:00 and 17:00 to 18:00 to treat the growth points of seedlings. Ploidy levels of mutated plants were determined by using the methods based on plant morphology, cytology, flow cytometric analysis and chromosome numbers of root tips.

Result  There were certain induction effects by using different concentrations of colchicine and oryzalin at different times, but the induction rate of colchicine was overall higher than that of oryzalin, and the highest induction rate was 32.18% using 2 g·L^–1 colchicine from 06:00 to 07:00. The ploidy identification result from the combination of methods based on plant morphology, cytology and flow cytometric analysis was the same as the result based on chromosome numbers of root tips.

Conclusion  The optimum method of obtaining autotetraploid was using 2 g·L^–1 colchicine from 06:00 to 07:00. The combination of plant morphology, cytology and flow cytometric analysis was a simple, convenient, large flux and accurate way to identify ploidy level.