Abstract
Fungal pathogens are the cause of the most common diseases in grapevine and among them powdery mildew represents a major focus for disease management. Different strategies for introgression of resistance in grapevine are currently undertaken in breeding programs. For example, introgression of several resistance genes (R) from different sources for making it more durable and also strengthening the plant defense response. Taking this into account, we cross-pollinated P09-105/34, a grapevine plant carrying both RUN1 and REN1 pyramided loci of resistance to Erysiphe necator inherited from a pseudo-backcrossing scheme with Muscadinia rotundifolia and Vitis vinifera ‘Dzhandzhal Kara,’ respectively, with the susceptible commercial table grape cv. ‘Crimson Seedless.’ We developed RUN1REN1 resistant genotypes through conventional breeding and identified them by marker assisted selection. The characterization of defense response showed a highly effective defense mechanism against powdery mildew in these plants. Our results reveal that RUN1REN1 grapevine plants display a robust defense response against E. necator, leading to unsuccessful fungal establishment with low penetration rate and poor hypha development. This resistance mechanism includes reactive oxygen species production, callose accumulation, programmed cell death induction and mainly VvSTS36 and VvPEN1 gene activation. RUN1REN1 plants have a great potential as new table grape cultivars with durable complete resistance to E. necator, and are valuable germplasm to be included in grape breeding programs to continue pyramiding with other sources of resistance to grapevine diseases.
Highlights
Grapevine (Vitis vinifera L.) is one of the most important fruit crops worldwide
Single nucleotide polymorphism of E. necator β-tubulin to discriminate genetically different groups A and B showed that all the isolates analyzed carry the restriction site recognized by AccI present only in the genetic group B
To further understand the grapevine defense response against E. necator associated with RUN1 and/or REN1 loci, we studied the expression patterns of genes related to immune response in plants
Summary
Grapevine (Vitis vinifera L.) is one of the most important fruit crops worldwide. It is affected by a large number of pathogenic microorganisms causing severe diseases with detrimental effects on yield and grape quality (Armijo et al, 2016b). Effective penetration continues with the development of feeding structures or haustoria, by which the fungus retrieves nutrients and secretes effectors that suppress host defenses, allowing the colonization of plant tissue surfaces by the development of secondary hypha. It produces dissemination structures or conidiophores, which sporulate to infect other host tissues and start a new infection cycle (Campbell et al, 2003; Glawe, 2008; Dry et al, 2010; Gadoury et al, 2012; Qiu et al, 2015)
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