Chromosome Karyotype Analysis and Evolutionary Trend of Half-Sib Families of Ancient Ginkgo Biloba L

The karyotype of 28 families from Shandong, Zhejiang, Guizhou and other 12 provinces exist in half-sib families of ancient Ginkgo biloba gemplasm repository was studied by squashing method with young leaves from these families. Results: The results showed that the number of chromosomes in 28 families was 2n=2x=24. The medium-short chromosomes and the medium-long chromosomes were dominant. The karyotype consists of three types: median region chromosome (m), submedian region chromosome (sm) and subterminal region chromosome (st). 71# family is the most primitive, while the 40# family is the most evolved. Families from southwestern China have a low degree of evolution, while those from eastern and southern China have a high degree of evolution.