Genetic Analysis of Diploid and Colchi-Tetraploid Mulberry (Morus indica and Morus alba) by Molecular and Morphological Markers

This study attempts a comparative assessment of morphogenetic changes in mulberry due to colchicine treatment and doubling of chromosome complement. Out of the 10 morphological (qualitative) traits studied, eight showed changes in the diploid in comparison to its tetraploid in one or more traits. The two traits (lobation and leaf apex) remained unchanged in all the varieties irrespective of the treatment with colchicine and doubling of chromosome number. Although the SPAD (Soil Plant Analytical Device) value increased in many tetraploids in comparison to its diploids, S-13 and S-34 showed a negative correlation for SPAD values and thereby increase in ploidy levels. However, the SPAD value was significantly correlated with increased ploidy in the case of K-2 and S-36. Stomatal frequency was negatively correlated with higher ploidy, except in the case of K-2 and S-13. Among the 45 primers utilized for DNA fingerprinting, 35 showed at least one marker variation among one or more pairs of diploid mulberry varieties with respect to their colchitetraploid derivatives. Sequence analysis of the diploids and its tetraploids showed variation in the noncoding region of the genome. The result of the present investigation reveals that colchicine is capable of inducing ploidy, thus interfering at the morphological and molecular levels. It also demonstrates that RAPD markers are informative in divulging genetic variations taking place in the genome.