SCREENING AND VALIDATION OF MOLECULAR MARKERS FOR RPI GENES IN POTATO VARIETIES AND INTERSPECIFIC HYBRID CLONES FROM THE VIR COLLECTION

BACKGROUND: Genes of potato resistance to late blight (Phytophthora infestans Mont. de Bary) have been identified and cloned in wild and cultivated potato species, foreign varieties, and clones. DNA markers of the Rpi-R1, Rpi-R2, Rpi-R3a, Rpi-R3b, and Rpi-blb1/Rpi-sto1 genes were found in Russian domestic varieties and breeding clones. However, no association between late blight resistance and the presence of these markers was found. To date nucleotide sequences of the Rpi-gene markers revealed in Russian domestic varieties and breeding clones has not been compared with the reference sequence of the target genes.

AIM: Screening potato samples from the VIR collection with different responses to late blight for Rpi genes and study of the structural features of their markers

METHODS: Molecular genetic analysis: PCR, cloning and sequencing of amplicons; phytopathological and statistical analysis

RESULTS: Molecular screening for the presence of the Rpi-R1, Rpi-R3b, Rpi-blb1 and Rpi-R8 genes markers detected differences among 95 potato genotypes in the frequency of Rpi-genes markers and a significant relationship between the presence of markers and the origin of clones of interspecific potato hybrids: Pearson’s chi-squared test = 28.68, (df = 15, p = 0.01). Out of 55 potato genotypes evaluated for resistance to late blight in field trials in 2023-2024, the resistant (11), moderately resistant (16), moderately susceptible (21) and susceptible (7) genotypes were identified. No association between the Rpi-R1, Rpi-R3b and Rpi-R8 genes markers presence in potato genotypes and their resistance to late blight was found. A relatively strong correlation of the Rpi-blb1 gene markers presence and resistance potato to late blight was found – Pearson’s chi-squared test = 8.209 (df = 1, р = 0.004). Both markers of the Rpi-blb1 gene were found in 12 resistant or medium-resistant potato genotypes, and in two medium-susceptible ones, missing in all susceptible genotypes. Verification of Rpi-genes markers was carried out in potato genotypes which differ for reaction to late blight. SNPs were detected in all amplicons obtained with primers recommended to CDS regions of the Rpi-R1, Rpi-R3b, Rpi-blb1, and Rpi-R8 genes. Markers of the Rpi-R1, Rpi-R3b, and Rpi-blb1 genes detected in Nayada, Magelanes, Sarpo Mira, and Sudarynya varieties and hybrid clones 171-3 and 16/27-09 have high similarity (over 99%) to the reference sequences. SNPs were found in similar positions of Rpi-R3b-378 in the hybrid clone 171-3 and Sarpo Mira, and in similar positions of Rpi-sto1-890 in the Sudarynya variety and clone 16/27-09. The CAPS marker IKR8-2-711+ BstAFI (467+244) was developed and allowed to identify the Rpi-R8 gene in Sarpo Mira, Nevsky and Gusar varieties..

CONCLUSION: The Rpi-R1-1205, Rpi-R3b-378, Rpi-blb1-821, and Rpi-sto1-890 markers are effective for the Rpi-R1, Rpi-R3b, and Rpi-blb1 genes detection in domestic potato varieties and hybrid clones. Both Rpi-blb1 markers are essential for selection the potato samples resistant to late blight.

Keywords

Solanum tuberosum, Phytophthora infestans, genes for resistance, DNA markers, breeding