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Powdery mildew (Erysiphe necator syn. Uncinula necator) and downy mildew (Plasmapora viticola) are the most harmful diseases to grapevine production in Turkey. The aim of this study was to generate hybrids between the susceptible Turkish wine grape variety ‘Bogazkere’ and powdery and downy mildew resistant microvine breeding lines and evaluate their resistance to these important diseases. Marker Assisted Selection (MAS) was used to determine the inheritance of powdery and downy mildew resistance and flower sex loci of the 36 F1 progeny plants obtained by cross-pollination at genotypic level. Based on the PCR results, phenotyping and leaf bioassay were performed to validate initial MAS for 11 and 9 representative progeny with four resistant and susceptible controls. As a result, two tall powdery and downy mildew-resistant vines, three powdery mildew-resistant microvines and two downy mildew-resistant microvines were obtained. The MAS results were also validated by leaf bioassays, which confirmed that resistance genes segregated to the F1 progeny are functional and provide resistance. To the best of our knowledge, this research provides the first photographic validation of the powdery and downy mildew resistance of the Turkish variety ‘Bogazkere’. Our findings could potentially provide the wine industry with a resistant wine grape cultivar and an addition to the wine grape germplasm, which could contribute to future breeding programs. Most importantly, the success of the resistance genes segregated into the candidate progeny could help significantly reduce the use of chemicals against grapevine pathogens.

The establishment of defense reactions to protect plants against pathogens requires the recognition of invasion patterns (IPs), mainly detected by plasma membrane-bound pattern recognition receptors (PRRs). Some IPs, also termed elicitors, are used in several biocontrol products that are gradually being developed to reduce the use of chemicals in agriculture. Chitin, the major component of fungal cell walls, as well as its deacetylated derivative, chitosan, are two elicitors known to activate plant defense responses. However, recognition of chitooligosaccharides (COS) in Vitis vinifera is still poorly understood, hampering the improvement and generalization of protection tools for this important crop. In contrast, COS perception in the model plant Arabidopsis thaliana is well described and mainly relies on a tripartite complex formed by the cell surface lysin motif receptor-like kinases (LysM-RLKs) AtLYK1/CERK1, AtLYK4 and AtLYK5, the latter having the strongest affinity for COS. In grapevine, COS perception has for the moment only been demonstrated to rely on two PRRs VvLYK1-1 and VvLYK1-2. Here, we investigated additional players by overexpressing in Arabidopsis the two putative AtLYK5 orthologs from grapevine, VvLYK5-1 and VvLYK5-2. Expression of VvLYK5-1 in the atlyk4/5 double mutant background restored COS sensitivity, such as chitin-induced MAPK activation, defense gene expression, callose deposition and conferred non-host resistance to grapevine downy mildew (Erysiphe necator). Protein-protein interaction studies conducted in planta revealed a chitin oligomer-triggered interaction between VvLYK5-1 and VvLYK1-1. Interestingly, our results also indicate that VvLYK5-1 mediates the perception of chitin but not chitosan oligomers showing a part of its specificity.