Presentation_1_Breeding new seedless table grapevines for a more sustainable viticulture in Mediterranean climate.pptx

The growing demand for sustainable and environmentally friendly viticulture is leading to a multiplication of breeding programs aimed at obtaining vines that are resistant to powdery mildew (PM) and downy mildew (DM), the two most damaging vine diseases. In Puglia, the most important Italian region for the production of table grapes, an extensive crossing program was launched in 2015 with 113 crosses, including elite table varieties, seedless varieties, and resistant varieties. The main seedling production parameters were measured for each cross. In particular, berries harvested as well as the number of seeds and seedlings obtained were considered. Approximately 103,119 seedlings were obtained and subjected to marker-assisted selection for seedlessness using the marker VvAGL11 and for resistance to PM and DM with appropriate markers. Approximately one third (32,638) of the progenies were selected as putative seedless and seventeen thousand five hundred-nine (17,509) were transferred to the field for phenotypic evaluation, including 527 seedless individuals putatively resistant, of which 208 confirmed to be resistant to DM, 22 resistant to PM, and 20 individuals that combined resistance and seedlessness traits. The work discusses the effects of parental combinations and other variables in obtaining surviving progeny and pyramiding genes in table grapes and provides useful information for selecting genotypes and increasing the efficiency of breeding programs for seedless disease-resistant grapes.</p

Table_1_Breeding new seedless table grapevines for a more sustainable viticulture in Mediterranean climate.xlsx

The growing demand for sustainable and environmentally friendly viticulture is leading to a multiplication of breeding programs aimed at obtaining vines that are resistant to powdery mildew (PM) and downy mildew (DM), the two most damaging vine diseases. In Puglia, the most important Italian region for the production of table grapes, an extensive crossing program was launched in 2015 with 113 crosses, including elite table varieties, seedless varieties, and resistant varieties. The main seedling production parameters were measured for each cross. In particular, berries harvested as well as the number of seeds and seedlings obtained were considered. Approximately 103,119 seedlings were obtained and subjected to marker-assisted selection for seedlessness using the marker VvAGL11 and for resistance to PM and DM with appropriate markers. Approximately one third (32,638) of the progenies were selected as putative seedless and seventeen thousand five hundred-nine (17,509) were transferred to the field for phenotypic evaluation, including 527 seedless individuals putatively resistant, of which 208 confirmed to be resistant to DM, 22 resistant to PM, and 20 individuals that combined resistance and seedlessness traits. The work discusses the effects of parental combinations and other variables in obtaining surviving progeny and pyramiding genes in table grapes and provides useful information for selecting genotypes and increasing the efficiency of breeding programs for seedless disease-resistant grapes.</p

Historical Introgression of the Downy Mildew Resistance Gene <i>Rpv12</i> from the Asian Species <i>Vitis amurensis</i> into Grapevine Varieties

<div><p>The Amur grape (<i>Vitis amurensis</i> Rupr.) thrives naturally in cool climates of Northeast Asia. Resistance against the introduced pathogen <i>Plasmopara viticola</i> is common among wild ecotypes that were propagated from Manchuria into Chinese vineyards or collected by Soviet botanists in Siberia, and used for the introgression of resistance into wine grapes (<i>Vitis vinifera</i> L.). A QTL analysis revealed a dominant gene <i>Rpv12</i> that explained 79% of the phenotypic variance for downy mildew resistance and was inherited independently of other resistance genes. A Mendelian component of resistance–a hypersensitive response in leaves challenged with <i>P. viticola</i>–was mapped in an interval of 0.2 cM containing an array of coiled-coil NB-LRR genes on chromosome 14. We sequenced 10-kb genic regions in the <i>Rpv12⁺</i> haplotype and identified polymorphisms in 12 varieties of <i>V. vinifera</i> using next-generation sequencing. The combination of two SNPs in single-copy genes flanking the NB-LRR cluster distinguished the resistant haplotype from all others found in 200 accessions of <i>V. vinifera</i>, <i>V. amurensis</i>, and <i>V. amurensis</i> x <i>V. vinifera</i> crosses. The <i>Rpv12⁺</i> haplotype is shared by 15 varieties, the most ancestral of which are the century-old ‘Zarja severa’ and ‘Michurinets’. Before this knowledge, the chromosome segment around <i>Rpv12⁺</i> became introgressed, shortened, and pyramided with another downy mildew resistance gene from North American grapevines (<i>Rpv3</i>) only by phenotypic selection. <i>Rpv12⁺</i> has an additive effect with <i>Rpv3⁺</i> to protect vines against natural infections, and confers foliar resistance to strains that are virulent on <i>Rpv3⁺</i> plants.</p> </div

Phenotypic distribution of downy mildew resistance.

<p>Two families segregating for <i>Rpv12⁺</i> (panel <b>A</b>) and for the combination of <i>Rpv12⁺</i> and <i>Rpv3⁺</i> (panel <b>B</b>) were analysed. Resistance scores in panel <b>A</b> are based on the OIV452 parameter (1 = most sensitive, 9 = most resistant) scored on field-grown seedlings under natural infection. Resistance scores in panel <b>B</b> are based on the cumulative OIV452 parameter (∑OIV452 = sum of daily OIV452 scores from 3 to 8 dpi) in artificially inoculated leaf discs. The average phenotypic value in the upper left corner of the panels <b>A</b>–<b>B</b> refers to individuals grouped by their allelic status at the <i>Rpv12</i> and <i>Rpv3</i> genes, which was estimated based on the flanking markers UDV014/UDV370 for <i>Rpv12</i>, and on UDV305/UDV737 for <i>Rpv3 </i><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0061228#pone.0061228-DiGaspero1" target="_blank">[8]</a>. Recombinants in those intervals were excluded from this estimate. QTL plots that explain the phenotypic variance shown in panel <b>B</b> are given in panel <b>C</b>.</p

Host–pathogen interaction observed between host and pathogen genotypes.

<p>Leaf discs of four host genotypes including (panels <b>A</b>, <b>E</b>) a double homozygous recessive grapevine (<i>Rpv12⁻</i> and <i>Rpv3⁻</i>), (panels <b>B</b>, <b>F</b>) a grapevine carrying <i>Rpv3⁺</i> in the absence of <i>Rpv12⁺</i>, (panels <b>C</b>, <b>G</b>) a grapevine carrying <i>Rpv12⁺</i> in the absence of <i>Rpv3⁺</i>, and (panels <b>D</b>, <b>H</b>) a double heterozygous grapevine for both <i>Rpv12⁺</i> and <i>Rpv3⁺</i> were inoculated with two isolates of <i>P. viticola</i>, (panels <b>A</b>–<b>D</b>) <i>Rude</i> (<i>avrRpv3⁺</i>/<i>avrRpv12⁺</i>) and (panels <b>E</b>–<b>H</b>) <i>Pv127</i> (<i>avrRpv3⁻</i>/<i>avrRpv12⁺</i>). Pictures were taken at 6 dpi.</p