Molecular Breeding (2021) 41 (12 - 76) - Delineating the elusive

Yaping Wang, Antje Habekuß, Rod J. Snowdon, Frank Ordon and Dragan Perovic (2021)
Delineating the elusive BaMMV resistance gene rym15 in barley by medium-resolution mapping
Molecular Breeding 41 (12 - 76)
Abstract: Barley mild mosaic virus (BaMMV), transmitted by the soil-borne protist Polymyxa graminis, has a serious impact on winter barley production. Previously, the BaMMV resistance gene rym15 was mapped on chromosome 6HS, but the order of flanking markers was non-collinear between different maps. To resolve the position of the flanking markers and to enable map-based cloning of rym15, two medium-resolution mapping populations Igri (susceptible) × Chikurin Ibaraki 1 (resistant) (I × C) and Chikurin Ibaraki 1 × Uschi (susceptible) (C × U), consisting of 342 and 180 F₂ plants, respectively, were developed. Efficiency of the mechanical inoculation of susceptible standards varied from 87.5 to 100% and in F₂ populations from 90.56 to 93.23%. Phenotyping of F₂ plants and corresponding F₃ families revealed segregation ratios of 250 s:92r (I × C, ÷² = 0.659) and 140 s:40r (C × U, ÷² = 0.741), suggesting the presence of a single recessive resistance gene. After screening the parents with the 50 K Infinium chip and anchoring corresponding SNPs to the barley reference genome, 8 KASP assays were developed and used to remap the gene. Newly constructed maps revealed a collinear order of markers, thereby allowing the identification of high throughput flanking markers. This study demonstrates how construction of medium-resolution mapping populations in combination with robust phenotyping can efficiently resolve conflicting marker ordering and reduce the size of the target interval. In the reference genome era and genome-wide genotyping era, medium-resolution mapping will help accelerate candidate gene identification for traits where phenotyping is difficult.
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Database assignments for author(s): Antje Habekuss, Frank Ordon, Dragan Perovic

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Barley mild mosaic virus	Barley (Hordeum vulgare)	Germany