Mapping and DNA sequence characterisation of the Rysto locus conferring extreme virus resistance to potato cultivar 'White Lady'.

Anita Sós-Hegedűs,Mihály Kondrák,Endre Barta,Edina Csákvári,Csilla Uri,Zsófia Bánfalvi,Andrea Kopp,István Cernák,Ajay Kumar,Mátyás Schiller,János Taller,Zsolt Polgár

doi:10.1371/journal.pone.0224534

Anita Sós-Hegedűs, Mihály Kondrák + Show 10 more

Open Access

https://doi.org/10.1371/journal.pone.0224534

Copy DOI

Abstract

Virus resistance genes carried by wild plant species are valuable resources for plant breeding. The Rysto gene, conferring a broad spectrum of durable resistance, originated from Solanum stoloniferum and was introgressed into several commercial potato cultivars, including ‘White Lady’, by classical breeding. Rysto was mapped to chromosome XII in potato, and markers used for marker-assisted selection in breeding programmes were identified. Nevertheless, there was no information on the identity of the Rysto gene. To begin to reveal the identification of Rysto, fine-scale genetic mapping was performed which, in combination with chromosome walking, narrowed down the locus of the gene to approximately 1 Mb. DNA sequence analysis of the locus identified six full-length NBS-LRR-type (short NLR-type) putative resistance genes. Two of them, designated TMV2 and TMV3, were similar to a TMV resistance gene isolated from tobacco and to Y-1, which co-segregates with Ryadg, the extreme virus resistance gene originated from Solanum andigena and localised to chromosome XI. Furthermore, TMV2 of ‘White Lady’ was found to be 95% identical at the genomic sequence level with the recently isolated Rysto gene of the potato cultivar ‘Alicja’. In addition to the markers identified earlier, this work generated five tightly linked new markers which can serve potato breeding efforts for extreme virus resistance.

Highlights

For sustainable intensification of crop production, disease control should, when possible, be achieved using genetics rather than using costly recurrent chemical sprays
Among the 457 tested F1 genotypes derived from a cross between ‘White Lady’ and ‘S440’, 220 resistant plants and 237 plants sensitive to PVYNTN infection were identified
Since STM0003 seemed to be too far from Rysto to start chromosome walking towards the resistance gene a fine mapping was carried out by testing the co-inheritance of the above listed four molecular markers with the virus resistant/sensitive phenotype in 400 genotypes derived from the ‘White Lady’ x ‘S440’ cross

Summary

Introduction

For sustainable intensification of crop production, disease control should, when possible, be achieved using genetics rather than using costly recurrent chemical sprays. Wild relatives of crop plants are a good source of genes for disease resistance. Potato (Solanum tuberosum), the world’s fourth most important food crop, following maize, wheat and rice, can be crossed with a number of wild Solanum species. Classical breeding for resistance is time-consuming, and it is extremely difficult to recover the parental combination necessary for beneficial. Rysto locus in potato design, data collection and analysis, decision to publish, or preparation of the manuscript

Methods

Results

Conclusion