Cytological studies on three species of Gastrodia, myco-heterotrophic orchids

Abstract

　Cytological studies on three species of Gastrodia, myco-heterotrophic orchids, were carried out. Gastrodia gracilis had the chromosome number of 2n=22. The chromosome complement at resting stage showed the complex chromocenter type, and the metaphase chromosomes showed a bimodal karyotype in length consisted of two large chromosomes of 2.7 μm and 20 small ones varied from 2.1-1.1 μm. Gastrodia nipponica had the 2n=24 chromosomes showing the intermediate type between the simple chromocenter type and the complex chromocenter type at resting stage, and a gradual karyotype at metaphase chromosomes varied from 2.2-1.1 μm. Gastrodia flavilabella showed the 2n=26 chromosomes showing the intermediate type between the simple chromocenter type and the complex chromocenter type at resting stage, and a gradual decrease in size from the largest to the smallest chromosomes at metaphase varied from 1.6-0.9 μm. Thus, the different chromosome numbers existed in Gastrodia; 2n=22 in G. gracilis, G. confusa (Aoyama and Tanaka 1986) and G. pubilabiata (Nakata 2004); 2n=24 in G. nipponica; 2n=26 in G. flavilabella; 2n=36 in G. elata (Aoyama and Tanaka 1986), G. angusta (n=18, Liang 1984) and G. javanica (Aoyama and Yokota 2011).