Karyotype analysis in rice. II. Identification of extra chromosomes in trisomic plants and banding structure on some chromosomes.

Abstract
In cultivated rice [Oryza sativa], 12 strains of primary trisomes were examined by karyotype analysis. Four strains, B, C, E and H types apparently had individual extra chromosomes K6, K12, K4 and K10, respectively. Between K5 and K9 and among K7, K8 and K11 chromosomes, there were some difficulty in discriminating one from the other. In well conditioned nuclei K5, K7, K9 and K11 extra chromosomes were carried by the A, D, L and F type trisomes. Extra chromosome K8 was present in G, I, J and K type trisomes. Three kinds of extra chromosomes (K1, K2, K3) were not found in these 12 strains. The modified technique for stretching the chromosomes appeared promising to characterize chromosome bands.