ABSTRACT
Potatoes are one of the most genetically diverse cultivated plants. Considering the huge numbers of accessions that are held collectively in gene banks, potato genetic resource collections are deemed to harbor a wealth of undisclosed allelic variants. The challenge is how to unlock this variation. Allele mining is a promising approach to dissect naturally occurring allelic variation at candidate genes controlling key agronomic traits, which have potential applications in potato improvement programs. It helps in tracing the evolution of alleles, identification of new haplotypes, and development of allele-specific markers for use in marker-assisted selection. True allele mining includes the analysis of non-coding and regulatory regions of the candidate gene(s), in addition to analyzing sequence variations in the coding regions of the important genes so as to cover most of the functional variations of relevance in the genes. Two major approaches such as Eco-TILLING and or sequencing-based allele mining are available for the identification of sequence polymorphism for a given gene in the naturally occurring populations. In potato, the identification of genes or chromosome regions responsible for agronomic traits had been extensively attempted in the last 30 years, mainly for disease resistance and tuber traits. Despite the success of these studies, only few discoveries were incorporated to plant breeding programs or used in surveying germplasm. With the complete genome sequence of potato it is envisaged that identification of allelic variants and genes, also in vivo functionality will be dramatically increased, given the availability of genetic sequences of potato and tools to assess gene function. Moreover, assisted breeding based on markers derived from these genes/alleles will be in an ideal situation where cross-over cannot occur between the marker and the gene responsible for the trait. The lessons learned from functional studies can also be applied to other Solanaceae, such as tomato, eggplant, petunia, tobacco, and pepper, which present a high level of synteny with potato.
