PT  - JOURNAL ARTICLE
AU  - Massonnet, Mélanie
AU  - Vondras, Amanda M.
AU  - Cochetel, Noé
AU  - Riaz, Summaira
AU  - Pap, Dániel
AU  - Minio, Andrea
AU  - Figueroa-Balderas, Rosa
AU  - Walker, M. Andrew
AU  - Cantu, Dario
TI  - Characterization of the grape powdery mildew genetic resistance loci in <em>Muscadinia rotundifolia</em> Trayshed
AID  - 10.1101/2021.11.23.469029
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.11.23.469029
4099  - http://biorxiv.org/content/early/2021/11/24/2021.11.23.469029.short
4100  - http://biorxiv.org/content/early/2021/11/24/2021.11.23.469029.full
AB  - Muscadinia rotundifolia cv. Trayshed is a valuable source of resistance to grape powdery mildew (PM). It carries two PM resistance (R) loci, Run1.2 on chromosome 12 and Run2.2 on chromosome 18. This study identified the nucleotide-binding leucine-rich repeat (NLR) genes composing each R locus and their associated defense mechanisms. Evaluation of PM disease development showed that introgression of both loci confers resistance to PM in a V. vinifera background, but with varying speed and intensity of the response. To better understand the effect of NLR composition on PM resistance, both haplotypes of each R locus were reconstructed and the gene models within each haplotype were manually refined. We found that the number and classes of NLR genes differed between Run1.2 and Run2.2 loci and between the haplotypes of each R locus. In addition, NLR genes composing Run1.2b or Run2.2 loci exhibited different levels of gene expression, pointing to candidate NLR genes responsible for PM resistance in Trayshed. Finally, a transcriptomic analysis that included six additional R loci showed differences in the defense mechanisms associated with Run1.2b and Run2.2 in response to PM and at constitutive level. Altogether, our results reveal that Trayshed’s R loci are composed of distinct NLRs that trigger different plant defense mechanisms in response to PM and at constitutive level, which would explain the variation of pathogen restriction between the two loci.Competing Interest StatementThe authors have declared no competing interest.