CMA staining analysis of chromosomes in several species of Aurantioideae

Fluorochrome staining with chromomycin A3 (CMA) was used to characterize and compare the CMA banding patterns of chromosomes of 17 species from 13 genera of Aurantioideae, which is one of the seven subfamilies of Rutaceae. All species used in this study had 2n = 18 chromosomes. These chromosomes were classified into five types based on the number and position of CMA-positive bands; B: one telomeric and one proximal band, C: two telomeric bands, D: one telomeric band, E: without bands and Dst: type D with a satellite chromosome. Each species possessed two or four types of chromosomes and unique CMA banding patterns. The CMA banding patterns were 6D + 12E in Clausena anisata (Willd.) Hook. f.,1C + 3D + 14E in Murraya koenigii (L.) Spreng., 1C + 11D + 6E in Murraya paniculata (L.) Jack, 1B + 1C + 10D + 6E in Merrillia caloxylon (Ridl.) Swing., 1C + 9D + 7E + 1Dst in Paramignya lobata Burkill, 2C + 5D + 11E in Severinia buxifolia (Poir.) Tenore, 5D + 13E in Hesperethusa crenulata (Roxb.) Roem., 16D + 2E in Citropsis gabunensis (Engl.) Swing. et M. Kell, 14D + 4E in Citropsis schweinfurthii (Engl.) Swing. et M. Kell, 8D + 10E in Atalantia monophylla DC., 1C + 3D + 14E in Atalantia ceylanica (Arn.) Oliv., 2D + 16E in Atalantia roxburghiana Hook. f., 18E in Swinglea glutinosa (Blanco) Merr., 2D + 16E in Aegle marmelos (L.) Corr., 4D + 14E in Afraegle paniculata (Schum.) Engl., 2B + 2D + 13E + 2Dst in Feronia limonia (L.) Swing. and 3B + 9D + 6E in Feroniella oblata Swing. The advanced genera in each tribe and subtribe such as Merrillia and Feroniella showed heterochromatin (CMA-positive bands) rich chromosome configuration in general. Swinglea glutinosa without heterochromatin rich chromosome, which is considered to be the most primitive chromosome configuration, seems to be the key genus for clarifying the evolution of the tribe Citreae.