GENOMIC CHARACTERISATION OF SACCHARUM SPECIES HYBRIDS OF SUBTROPICAL INDIA: PREFERENTIAL CHROMOSOME PAIRING

摘要

Genomic affinity studies provide useful information on chromosome pairing relationships, and hence on transferring of desirable traits from one species to another. In general, a higher chiasma frequency in a species hybrid would indicate better pairing among the parental chromosomes involved. Although important in stabilising the transmission genetics and fertility of polyploid crops, chromosome pairing behaviour of many of the commercial or near commercial sugarcane genotypes has not been studied, in spite of their being used as parents in sugarcane breeding programs with special reference to sub-tropical India. With this in view, eight elite sugarcane genotypes (Saccharum spp. hybrids) of subtropical India were examined to elucidate the pattern oftheir bound arm associations at meiotic metaphase I. Algebraic estimations obtained from the observed data indicated a decrease in the frequency of chiasmate associations. A moderately strong (more than 2/3rd) diploidisation of chromosome pairing was observed. The present paper highlights the preferential bivalent formation vis-à-vis reduced multivalent frequency at diakinesis and metaphase I, and its role in ascertaining genomic stability.