Find in Library

Sugarcane, which is an allopolyploid with genome contributions from Saccharum officinarum and S. spontaneum, is having high chromosome number of 2n=100 to 130 in different cultivars. The ‘Saccharum complex’ has species with varying ploidy level and the chromosome number ranges from 2n=20 to ~200. The high polyploidy and heterozygosity due to hybridization has restricted the classical genetic studies in sugarcane. There have been many studies recently on the effect of genome duplication and hybridization in gene expression and evolution of allopolyploids. In newly formed polyploids the diploidization mechanisms operate for stabilizing the genomes. Genome restructuring and gene expression modifications such as gene silencing and subfractionalization occur by which the allopolyploid may even have altered phenotype compared to the parents. Gene redundancy due to polyploidy provides a selective advantage for a wider geographical adaptation, increased vigour, sucrose and fibre content of sugarcane crop. There is increased global demand for alternative fuel sources and sugarcane is gaining importance as a biofuel crop with its high biomass production potential, besides being a major sugar crop. This review is on the significance of polyploidy in conventional and molecular approaches to genetic improvement of sugarcane in view of a large amount of recent literature available on the genomics and gene expression in allopolyploids. There are many features in sugarcane that makes it a model crop for studying the effects of allopolyploidy and hybridity in plants.