The chromosome number and karyotype analysis of Mirabilis jalapa

Mirabilis jalapa was perennial herbal flower with powerful capacity of reproduction as a invasive plant. This paper analyzed the chromosome number and karyotype of M. jalapa with treatments such as 12 h low temperature pretreatment of root tip, fixation with Carnoys solution, cell wall acid hydrolysis and staining. The results showed that the somatic chromosome number of the M. jalapa was 2n=56, and karyotype formula was K=2n=2x=28m+22sm+4st+2m（sat）, which belonged to 2B type. The variation range of the chromosome length was 2.330.78 m, and which was classified to small type. As the coefficient of nonsymmetry was 63.8%, the chromosome of M. jalapa was nonsymmetrical type. The study would provide some references to cytology for preventing and controlling M. jalapa.