Chromosome Karyotype Analysis and Evolutional Trend of Ancient Ginkgo biloba Half-sib Families

This study was based on the karyotype and evolution trend of 28 families from Shandong, Zhejiang, Guizhou and other 12 provinces which existed in ancient Ginkgo biloba half-sib families germplasm repository by squashing method with random young leaves as test materials. The result showed that the karyotype of all 28 families could be described as 2n=2x=24; The chromosome composition based on relative length of main medium-short and medium-long; The karyotype was mainly composed of median centromere chromosome (m), nearly median centromere chromosome (sm) and acrocentric chromosome(st), and the karyotype could be divided into 4 types, which were 2A, 2B, 3A and 3B; 40^# might be the most advanced while 71^# family might be the most primitive family. The families from southwest of China were more primitive, while the families from east and south were more advanced.