The Himalayan strains of maize, especially Sikkim primitives (SP 1 and SP 2) have aroused considerable interest in recent years among crop plant evolutionists. In order to obtain an explanation of the presence of primitive maize in the North-Eastern Himalayan region, cytological studies were undertaken. Distribution of constitutive heterochromatin was studied in some Indian and exotic strains of maize and teosinte during mitosis. Table 1 gives an idea of the C-banding pattern of some of these strains.
There are striking differences in the pattern of C-banding between primitive forms of maize and teosinte. The chromosomes of primitive strains of maize carry fewer and relatively smaller bands than in the evolved races of maize and teosinte. Apart from the conspicuous bands which are found at the terminal and sub-terminal regions, smaller and less distinct bands were also observed at the median and sub-median positions on chromosomes in teosinte and some strains of maize.
The banding pattern in chromosomes of the Himalayan races SP 1 and SP 2, which are derivatives of a widely grown cultivated variety variously named as Murli, Muralia, Poorvi Botapa, etc. in Sikkim, Meghalaya, and other parts of North-eastern Himalayan regions, do not correspond to those in the Mexican primitives. SP 1 and SP 2 chromosomes carried as many as 14 bands. Other collections from Meghalaya and Sikkim, however, showed fewer C-bands.
J. K. S. Sachan, K. R. Sarkar and Ryuso Tanaka*
*Botanical Institute, Faculty of Science, Hiroshima University, Hiroshima, 730, Japan
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