The Contribution of Traditional Potato Breeding to Scientific Potato Improvement

Conventional potato breeding refers to development of new cultivars from sexual crosses followed by clonal propagation and selection. Nearly all new varieties of potato still emerge from this process free from modern technologies of gene insertion. Conventional breeding remains the most important force for introduction of new phenotypes underlain by new genes. However, these come from already selected potato breeding lines or named varieties or from wild potatoes or more distant solanaceous relatives that are amenable to somatic hybridization. Potato breeders are constantly searching for new germplasm, in part because the potato as a crop still remains highly vulnerable to biotic and abiotic stresses. In addition, the widening of the genetic base is seen as a means of increasing heterozygosity. Despite a highly conscious import of genetic variability, commercial varieties often emerge from a relatively restricted genetic pool. This is due to the long list of traits that must fall within narrow boundaries of performance. The potato must be able to navigate the conditions of modern agriculture, withstand unusual weather events, and arrive at harvest with skin and flesh appealing to the market for which it is intended. A storage period must also be endured during which appearance and suitability for processing or the consumer’s kitchen must be maintained. A lapse in any of these phases usually signals that a new variety will exit commercial use as fast as it entered. The inconvenient accompaniment of introducing exotic genetic variation is that the breeding products are often outside of the targeted market niche. It is not surprising that many new varieties stem from crosses from older named varieties. Efforts to diversify are in conflict with conformism leading to relatively high co-ancestry coefficients between advanced breeding lines. Conventional breeding has advanced through the last hundred years the appearance, sugar status, Verticillium resistance, and yield of larger sized tubers in statistically robust ways. Potato arrived from the new world and very quickly became the secret solution to famine for the poor by virtue of its productivity and nutrient content. Meanwhile, in modern times, challenges to the consumption of potato come from a sedentary and carbohydrate over-satiated society. The genetic repository of potato germplasm is so rich that a new era of potato varieties beneficial to health may be at hand. Conventional breeding will certainly be a major part of this.