On the Value of Wild Solanum Species for Improved Crop Disease Resistance: Resistances to Nematodes and Viruses

Abstract

The genus Solanum includes important crop species and numerous wild species. The wild Solanum species are a genetic diversity treasure trove useful for the improvement of crops, with disease resistance being of critical importance. In this chapter, I review the status of research and breeding efforts for improved nematode and virus resistance in Solanum crops, especially potato and tomato. In total, 33 disease resistance genes are described; virtually all originate from wild relatives of potato and tomato. This observation underscores the utility of wild Solanum species and the need to prioritize their conservation through in situ and ex situ approaches. Trends in research well positioned to impact trait discovery in wild Solanum species and introgression into crop species are outlined. Included are the potential to mine genebank collections for novel disease resistance alleles using target DNA sequencing approaches, visualization of deep evolutionary and allele diversification patterns across the Solanaceae, and streamlined gene mapping and cloning methodologies. The potential impacts of Marker Assisted Breeding, genetic transformation, gene-editing, and conversion of cultivated potato to a diploid species are explored. A growing world population and changing global climate that requires crop plants to tolerate increasingly chaotic production environments present the need for urgent investment in the genetic improvement of crops, with crop wild relatives being critical donors of useful traits.