Funktionsanalyse der asiatischen Resistenzloci Rpv12 und Rpv10 gegen den Falschen Mehltau (Plasmopara viticola) der Weinrebe
Zusammenfassung der Projektergebnisse
This project contributed to the analysis of Plasmopara viticola resistance mediated by the Asian resistance loci Rpv10 and Rpv12 in grapevine. The Rpv10 locus, already studied in some detail in previous investigations, was reduced from 84 to 54kb by a preliminary recombination analysis using novel InDel markers. The delimited region still contains the annotated RPS5-like NLR resistance gene as primary candidate to mediate resistance, besides an AP2/ERF type transcription factor gene. Further work should extend the recombination analysis to possibly reduce the locus to only one resistance gene candidate. The newly developed InDel markers will be helpful to this purpose and will also improve marker assisted breeding of resistant grapevines aiming at introgressions of Rpv10. The Rpv12 locus was shown to mediate a post-penetration resistance mechanisms with the production of rapid local necroses around the infection sites. Mycelial development was strongly inhibited in heterozygous Rpv12 carriers and almost absent in carriers of the locus Rpv12 in the homozygous state, indicating en effect of homozygosity on the resistance phenotype. A heterozygous carrier of Rpv12 was used to sequence its whole genome with separation of both haplophases by the TrioBinning approach performed in cooperation with CeBiTec Bielefeld (B. Weishaar and group) and MPI Cologne (B. Hüttel and group). The sequence was annotated in combination with extensive RNA-Seq data and differentially expressed genes during pathogen challenge were identified. The locus itself was resolved in the resistant haplotype. It covers one cluster of four ankyrin-like/ACD6-like genes that appear activated by pathogen challenge particularly in Rpv12 carriers in one cluster. In Arabidopsis, these genes are described to be involved in salicylic acid signaling and rapid cell death reactions. Their induction is in agreement with the cytological observation of rapid necrosis. A second cluster contains six putative resistance gene analogues probably involved in pathogen recognition. The locus showed strong structural variation from the corresponding genomic stretch of the susceptible haplotype and the Vitis reference genome. This new insight allows the highly advanced and well targeted use of the Rpv12 locus in grapevine resistance breeding. Molecular markers flanking both clusters applicable in marker assisted selection became available through this research. The results are a cornerstone for sophisticated approaches combining several resistance loci for durable resistance with detailed description and delimitation of the genetic factors required. However, functional analysis of the individual genes identified here newly as candidates for Rpv12 resistance will require gene transfer or gene knock-out experiments. These are very slow-going due to difficult and long-lasting regeneration procedures for grapevine and thus await future research.
Projektbezogene Publikationen (Auswahl)
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2021. Zytologische und molekulare Studien zum Resistenzlocus Rpv12 gegen den Falschen Mehltau der Rebe (Plasmopara viticola). Dissertation. Karlsruhe Institute of Technology (KIT). Faculty of Chemistry and Life Sciences.
Müllner, S.
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2022. The effect of homozygosity of locus Rpv12 on downy mildew resistance of grapevine leaves. Vitis 61, 71–76.
Müllner, S. & Zyprian, E.
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Phased grapevine genome sequence of anRpv12carrier for biotechnological exploration of resistance toPlasmopara viticola. (2022, 8, 6). American Geophysical Union (AGU).
Frommer, Bianca; Müllner, Sophia; Holtgräwe, Daniela; Viehöver, Prisca; Hüttel, Bruno; Töpfer, Reinhard; Weisshaar, Bernd & Zyprian, Eva
