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[Objective] This study aimed at investigating the chromosomal characteristics and karyotypes of Gynura medica.[Method] Stem tips of G.medica seedlings were taken every 20 min from 6:30 to 10:30 am,and then were treated and squashed.The slices were observed under a microscope for investigating the chromosomal number and karyotypes of the cells in metaphase in which the chromosomes were well dispersed.[Result] In the total 102 stem tip cells in metaphase,96.08% of cells were with 20 chromosomes,and 3.92% of cells were with 40 chromosomes.Optimal time for sampling was from 7:50 to 9:30 am,when more cells were in metaphase.[Conclusion] G.medica is the diploid plant with 20 chromosomes.Karyotype analysis gets formula 2n = 2x = 20m,and all 10 pairs of chromosomes belong to type 1A.The article reports the chromosomes characteristics of G.medica firstly.
[Objective] This study aimed at investigating the chromosomal characteristics and karyotypes of Gynura medica. [Method] Stem tips of G. medica seedlings were taken every 20 min from 6:30 to 10:30 am, and then were treated and squashed. slices were observed under a microscope for investigating the chromosomal number and karyotypes of the cells in metaphase in which the chromosomes were well dispersed. [Result] In the total 102 stem tip cells in metaphase, 96.08% of cells were with 20 chromosomes, and 3.92 % of cells were with 40 chromosomes. Optimal time for sampling was from 7:50 to 9:30 am, when more cells were in metaphase. [Conclusion] G. medica is the diploid plant with 20 chromosomes. Karyotype analysis gets formula 2n = 2x = 20m, and all 10 pairs of chromosomes belong to type 1A. The article reports the chromosomes characteristics of G.medica first.