Molecular markers save time and money for evaluating virus resistance in potato breeding

Breeding potatoes for disease resistance can be costly. A recent study shows that compared with the conventional approach, the use of molecular marker analysis allows breeders to evaluate virus resistance twice as fast, while saving nearly 90% of the cost.

Hannele Lindqvist-Kreuze, a molecular breeder at CIP in Lima, Peru, is part of a team that has shown how molecular markers can be used to cut costs in plant breeding. By using molecular markers to identify virus resistance in potato plants, plant breeders can cut costs by 88%, compared with conventional methods. “We are constantly looking for ways to improve the efficiency of the potato breeding program at CIP, and marker-assisted selection (MAS) is certainly a great tool to take us faster towards the goal of increased genetic gains in the farmers’ fields,” says Lindqvist-Kreuze.

The conventional method of evaluating resistance to PLRV (potato leafroll virus) and potato virus Y involves several steps of tedious, painstaking work. To confirm the results, the potato plants also have to be screened for viruses using serological tests for the antibodies in a lab. Moreover, the virus resistance assays require several plants of the same type which have to be producing tubers or they have to be propagated by cuttings (i.e., bigger, older plants). The whole procedure can take 105 days.

With the new, alternative method, molecular markers are used to identify the genes that are known to confer resistance to disease. These genes can be assayed from a single leaf of a young plant, by isolating the DNA and assessing it for the presence or absence of the genes. The procedure can be accomplished in just 50 days and the resistance to both viruses can be tested at once, from the same sample. The costs of using the conventional phenotyping method was USD68.80 per plant, versus just USD8.00 for molecular markers. Costs could be lowered even further using a high- throughput genotyping system, if many samples are assayed at once.

Therefore, much time and money can be saved by using molecular marker analysis. Conventional phenotyping costs over eight times as much money and takes twice as long, and requires more screenhouse space and expensive serological and other tests to check for disease resistance. Although molecular markers are frequently asserted to be efficient, Lindqvist-Kreuze and her team provide actual numbers to confirm such claims. In the future, breeders will be able to select resistant genotypes and cross them earlier in the breeding cycle.