Karyotype Analysis in Three Morphological Forms of Lasia spinosa (L.) Thwaites (Araceae)

抄録

Three morphological forms based on the leaf character of Lasia spinosa (L.) Thwaites viz. i) sagittate, ii) lamina dissected and iii) a mixed of sagittate and lamina dissected were cytogenetically investigated. The sagittate form had 2n=27. A minute subtelocentric chromosome was found in the sagittate form. Both lamina dissected and mixed form possessed 2n=26 chromosomes. The centromeric formula of sagittate form was 19m+7sm+1st. It was 9m+15sm+2st in the lamina dissected form and 14m+11sm+1t in the mixed form. The total length of 2n chromosome complement was 102.23 μm in the sagittate form, 57.78 μm in the lamina dissected form and 74.46 μm in the mixed form. In orcein-staining, one satellite was found in sagittate form, 2 in the lamina dissected form and 5 in the mixed form. In CMA-staining, 2 big CMA-positive satellites were found in the sagittate form. Two small CMA-positive satellites were found in the lamina dissected form. The mixed form had 1 big and 1 small satellite. Two CMA-positive bands were found in sagittate, 5 in lamina dissected and 3 in mixed form. The percentage of GC-rich region was 2.88 in the sagittate, 11.23 in the lamina dissected and 6.79 in the mixed form. The above features indicated that the mixed form might be a natural hybrid between the sagittate and the lamina dissected form. Each form possessed specific karyotype which could be applied to elucidate the taxonomic rank of these 3 forms in Lasia spinosa.