Phenotypic and epigenetic variation induced in newly synthesized allopolyploids and autopolyploids of potato

Abstract

Polyploidy is one of the most important events in plant evolution: the evidence suggests that more than 70% of the angiosperms underwent some event of genomic duplication during their diversification. In potato, the third more important crop worldwide, the effects of autopolyploidization at morphological, physiological and molecular levels have been explored and no evident phenotypic superiority of polyploid lines respect to the parental diploid lines has been found. On the other hand, the consequences of allopolyploidization have not been analysed so far in potato from a molecular point of view. In this work we study the variability induced by whole genome duplication in potato auto and allotetraploids obtained by chromosomal duplication of a S. kurtzianum genotype (autopolyploid model) and by chromosomal duplication of a diploid interspecific hybrid between S. tuberosum and S. kurtzianum (allopolyploid model). Polyploid lines in both models showed a tendency to increase the vigor in phenotypic characters compared with diploid parent they derived from. AFLP analysis showed no polymorphism between parental diploid and derived polyploids lines. However, there were DNA methylation changes between diploids and polyploids, indicating that polyploidization alters the epigenetic patterns in potato. It is possible that the superiority of the tetraploid can be explained as a heterotic response dependent on the presence of heterozygous loci and epistatic interactions inducing alterations in the gene regulation of the polyploid genomes.