NEW CHROMOSOME COUNTS AND NUCLEAR CHARACTERISTICS FOR SOME MEMBERS OF GESNERIACEAE SUBFAMILY CYRTANDROIDEAE FROM CHINA AND VIETNAM

Abstract

The morphological characteristics of mitotic interphase, prophase and metaphase nuclei were analysed for 21 taxa in 14 genera from three different tribes of subfamily Cyrtandroideae (Gesneriaceae) from Asia. Interphase nuclei were classified into three categories: (1) complex chromocentres, as in Ancylostemon, Briggsia, Briggsiopsis, Chirita, Loxostigma, Lysionotus, Oreocharis, Petrocosmea, Raphiocarpus and Whytockia, (2) simple chromocentres, as in Paraboea and Rhabdothamnopsis, and (3) round prochromosomes, as in Anna and Didymocarpus. Species with complex chromocentres seem to be most common among all three tribes. The data further indicate that tribe Didymocarpeae is cytologically much more heterogeneous than other tribes, which accords with the diversity in morphological characters. Three types of chromosome condensation pattern during mitotic prophase were observed, here described as interstitial, gradient and proximal. Except for Ancylostemon, exhibiting a proximal type, and Lysionotus and Whytockia possessing a gradient type, all other species analysed to date exhibit the interstitial type. Our study also reports the chromosome numbers of 12 species in 10 genera of subfamily Cyrtandroideae from China and Vietnam; 11 of these counts are new.