Abstract
Key messageWe have elucidated the Andigena origin of the potato Ryadg gene on chromosome XI of CIP breeding lines and developed two marker assays to facilitate its introgression in potato by marker-assisted selection.Potato virus Y (PVY) is causing yield and quality losses forcing farmers to renew periodically their seeds from clean stocks. Two loci for extreme resistance to PVY, one on chromosome XI and the other on XII, have been identified and used in breeding. The latter corresponds to a well-known source of resistance (Solanum stoloniferum), whereas the one on chromosome XI was reported from S. stoloniferum and S. tuberosum group Andigena as well. To elucidate its taxonomic origin in our breeding lines, we analyzed the nucleotide sequences of tightly linked markers (M45, M6) and screened 251 landraces of S. tuberosum group Andigena for the presence of this gene. Our results indicate that the PVY resistance allele on chromosome XI in our breeding lines originated from S. tuberosum group Andigena. We have developed two marker assays to accelerate the introgression of Ryadg gene into breeding lines by marker-assisted selection (MAS). First, we have multiplexed RYSC3, M6 and M45 DNA markers flanking the Ryadg gene and validated it on potato varieties with known presence/absence of the Ryadg gene and a progeny of 6,521 individuals. Secondly, we developed an allele-dosage assay particularly useful to identify multiplex Ryadg progenitors. The assay based on high-resolution melting analysis at the M6 marker confirmed Ryadg plex level as nulliplex, simplex and duplex progenitors and few triplex progenies. These marker assays have been validated and can be used to facilitate MAS in potato breeding.
Highlights
Potato viruses are increasingly a source of concern with less predictable insect vector population due to climate changes directly on reducing crop yield, and because1 3 Vol.:(0123456789)Theoretical and Applied Genetics (2018) 131:1925–1938 they spread through healthy-looking tubers (Solomon-Blackburn and Barker 2001)
This paper describes the development of a reliable, cost-effective and a mid-throughput marker assay of the RYSC3, M45 and M6 markers to be used in large-scale progeny screening for potato virus Y (PVY) resistance, and a molecular assay of the M6 marker for assessing the dosage of resistant alleles of Ryadg referred to as a “plex” assay
The RYSC3 marker allele associated with resistance was present in the clone A6 which is susceptible to PVY and used for PVY strain identification
Summary
Potato viruses are increasingly a source of concern with less predictable insect vector population due to climate changes directly on reducing crop yield, and because1 3 Vol.:(0123456789)Theoretical and Applied Genetics (2018) 131:1925–1938 they spread through healthy-looking tubers (Solomon-Blackburn and Barker 2001). Genes for resistance to PVY have been mapped from S. chacoense, S. stoloniferum, S. tuberosum group Andigena and S. tuberosum group Tuberosum (Simko et al 2007). Brigneti et al (1997) located the PVY resistance gene on chromosome XI using a large population derived from the cross 83W28-50 × I-1039 (I-1039 carries the Rysto gene) and referred to it as Rysto. Ny-Smira gene from cultivar Sarpo Mira was mapped to a location on the chromosome IX corresponding to Rychc and Ny-1 genes for PVY resistance. Ny(o,n)sto gene from S. stoloniferum was identified in potato cultivars in a position corresponding to the Rysto on chromosome XI described by Brigneti et al (1997) (Van Eck et al 2017)
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