Screening for Resistance to PVY in Australian Potato Germplasm

Abstract

Potatoes are an important human food crop, but have a number of yield limiting factors, including disease susceptibility. Potato virus Y (PVY) is found worldwide, and is one of the main virus problems for potato growers. PVY is transmitted by aphids and mechanically by machinery, tools and people, and symptoms are variable across cultivars and strains, including being symptomless in some cultivars. Therefore, breeding resistant cultivars is the best way to control this virus. This study phenotypically screened 74 of the main commercial cultivars and a few other select cultivars grown in Australia, in order to identify sources of resistance to PVY. The cultivars were screened against PVY O and PVY NTN , with 23 out of 71 resistant to PVY O and 13 out of 74 resistant to PVY NTN , and all these 13 were resistant to both strains. When the phenotypic screening was compared to the results listed on the European Cultivated Potato Database, the majority of results were found to be consistent. We then evaluated three molecular markers RYSC3, M45, and STM0003 for the extreme resistance genes Ry adg and Ry sto , to validate the usefulness of the markers for marker-assisted selection (MAS) on Australian germplasm. The degree of correlation between the resistance phenotypes and the RYSC3, M45, and STM0003 markers for Ry adg and Ry sto conferred PVY resistance was determined. Three cultivars amplified the RYSC3 marker, while the M45 marker amplified the same 3 and an additional 9. Of the 12 cultivars, 11 phenotyped as resistant, but 1 was susceptible. The STM0003 marker was amplified from only 2 cultivars that both had resistant phenotypes. The RYSC3, M45, and STM0003 markers were therefore able to identify all the 13 cultivars that were resistant to both strains of PVY. Therefore, these markers will enable the identification of genotypes with resistance to PVY, and enable PVY resistant parents to be used for the development of superior progeny; these genetic markers can be used for MAS in the Australian potato breeding program.Genes 2020, 11, 429 2 of 15 mosaic symptoms on the leaves, and this can create a major risk for the spread of the virus in certified seed schemes [8]. Furthermore, the lack of symptoms in infected plants means that visual inspection will generally be ineffective, and that such plants provide a source of PVY inoculum in production areas. Therefore, breeding resistant cultivars is the best way to control this virus and remove inoculum.An effective potato breeding program aims to breed new cultivars that have traits that are superior or equivalent to those of current cultivars. In order to do this, potential parents need to be identified, which contain genes that control at least 40 desirable traits [9,10]. A list of traits that are important for the breeding of improved cultivars in Australia and their genetic control were listed by Slater et al. [10]. A number of these characters are considered to be controlled by single dominant genes, as they exhibit qualitative phenotypic variation. Simko et al.[11] l...

Genome Enhanced Marker Improvement for Potato Virus Y Disease Resistance in Potato

“…The marker systems currently in place for the selection of PVY resistant germplasm are ineffective due to the breakdown of association between the markers and the PVY resistant trait [25]. In this paper we will show that M6 will likely fall into the same category as other previously reported markers, resulting in no predictive diagnostic markers available that are 100% accurate for Ry adg .…”

“…Two populations (Lady Christl × La Ratte and Lady Claire × Friar consisting of 93 and 45 individuals, respectively) were developed to validate the developed molecular markers. Crosses were chosen on the basis that one cultivar (Lady Christl and Friar) contained the PVY resistance gene, Ry adg [25]. Seeds from the crosses were collected and grown to seedlings and all plants available from each cross sampled for DNA screening at 4 weeks.…”

“…Several markers have been developed to select for cultivars containing Ry adg , these include the sequence-characterized amplified region (SCAR) marker RYSC3 [22] and converted amplified fragment length polymorphism (AFLP) marker M45 [23], that have been primarily used to genotype the Australian collection. Slater et al [24,25] performed genotyping using both markers and found 10/74 cultivars were incorrectly genotyped as susceptible to PVY using the RYSC3 marker, while M45 delivered superior accuracy with only cv. Emma genotyping as resistant using both markers yet is phenotypically classified as susceptible to PVY.…”

“…With the genomic resources now available, the application of genetic mapping to find causal markers with more precision than classical biparental maps has been enabled. The aims of this paper are to use existing genomic resources and genotypic data from the Australian potato cultivar collection [24,25,31] to investigate the position of the Ry adg gene on Chromosome XI and develop a diagnostic SNP marker system for the reliable detection of the resistance allele for implementation in potato varietal improvement.…”

Single Nucleotide Polymorphisms: A Modern Tool to Screen Plants for Desirable Traits

“…These gave way to the popular techniques Amplified fragment polymorphism (AFLP) and Simple sequence repeats (SSRs) due to their ease in detection and automation. Simple sequence repeats have been extensively applied to screen for resistant germplasms, biotic and abiotic stress and variety identification in potato, groundnut rice [1][2][3]. SSR markers are generally PCR-based, their technicality is simple and relatively cheap.…”