CYTOLOGICAL STUDIES ON ERICACEAE (I)

CHROMOSOME NUMBERS AND KARYOTYPES OF THE SUBGENUS RHODODENDORON

Abstract

Somatic chromosome numbers and karyotypes of seven species in the subgenus Rhododendoron (Ericaceae) were studied. Root tips of these plants were pretreated with 8-oxyquinorin and fixed with ethanol-acetic acid solution (3:1 mixing ratio). After being hydrolized in 1N-HCl, the materials were squashed in acetic orcein on a slide glass, and preserved for the microscopic observation.The results obtained are summarized as follows:
R. Kaempferi, K=(2n)=26A^m+^tB^sm+4C^sm+D^m+3E^t+F^t+G^m+H^t
R. kiusianum, K=(2n)=262A^st+B^sm_sc+C^st+2D^t+E^m+2F^t+G^st+H^t+2I^m
R. Oomurasaki, K=(2n)=26^tA^t+2B^m+2C^sm+6D^m+E^m+F^sm
R. linearifolium macrosepalum, K=(2n) =26A^sm+2B^t+C^m+D^sm+2E^t+2F^m+G^t+H^m+2I^m
R. obtsum (KURUME, KURENO-YUKI), K=(2n) =26A^st+^tB^t+C^m+D^t_sc+E^st+F^t+G^m+2H^t+2I^m_sc +2J^m
R. Schlippenbahii, K=(2n) =26A^m_st+B^t+C^sm+2D^st+E^m+F^t+^tG^t+H^st+3I^m+J^m
R. indicum (AZALEA, SUMIYOSHI-NISHIKI), K=(2n) =26^tA^st+^tB^sm+2C^m+^tD^sm+2E^m+F^m_sc+G^t+2H^st+^tI^t+J^m
From the similarity in karyotypes of R. Kaempferi, R. kiusianum, and R. Oomurasaki, these three species seems to be akin with each other. The seminal-formation of R. obtusum occurs scarcely and R. indicum is sterile. These two species carry different karyotypes from the other species, such as C^m chromosome in the former plant and ^tA^st and ^tD^sm in the later. These chromosomes may have some relation to the sterility of these plants.