A Novel Pear Scab (<i>Venturia nashicola</i>) Resistance Gene, <i>Rvn3</i>, from Interspecific Hybrid Pear (<i>Pyrus pyrifolia</i> × <i>P. communis</i>)
2021
Sewon Oh | Hyeondae Han | Daeil Kim
Asian pear scab is a fungal disease caused by <i>Venturia nashicola</i>. The identification of genes conferring scab resistance could facilitate the breeding of disease-resistant cultivars. Therefore, the present study aimed to identify a scab-resistance gene using an interspecific hybrid population ((<i>Pyrus pyrifolia</i> × <i>P. communis</i>) × <i>P. pyrifolia</i>). Artificial inoculation of <i>V. nashicola</i> was carried out for two years. The segregation ratio (1:1) of resistant to susceptible individuals indicated that resistance to <i>V. nashicola</i> was inherited from <i>P. communis</i> and controlled by a single dominant gene. Based on two years phenotypic data with the Kruskal–Wallis test and interval mapping, 12 common markers were significantly associated with scab resistance. A novel scab resistance gene, <i>Rvn3</i>, was mapped in linkage group 6 of the interspecific hybrid pear, and co-linearity between <i>Rvn3</i> and one of the apple scab resistance genes, <i>Rvi14</i>, was confirmed. Notably, an insertion in pseudo-chromosome 6 of the interspecific hybrid cultivar showed homology with apple scab resistance genes. Hence, the newly discovered <i>Rvn3</i> was considered an ortholog of the apple scab resistance gene. Since the mapping population used in the present study is a pseudo-BC<sub>1</sub> population, pyramiding of multiple resistance genes to pseudo-BC<sub>1</sub> could facilitate the breeding of pear cultivars with durable resistance.
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