Population Diversity of Grape Phylloxera in California and Evidence for Sexual Reproduction

Abstract

Until recently, the foliar forms of grape phylloxera have been absent or very rare in California, and nodosities have not been common on resistant rootstocks. Foliar phylloxera are now widely spread in the mothervine plantings of grape rootstock nurseries in Yolo and Solano counties. Nodosities on resistant rootstocks have also been frequently observed. To determine the genetic relationships within and among these seemingly new types of phylloxera, collections were made across California from 2009 to 2011. Foliar-feeding phylloxera strains were collected from rootstock mothervines at the National Clonal Germplasm Repository in Winters, CA; University of California, Davis (UCD), vineyards; and six commercial rootstock nursery plantings in Yolo and Solano counties. Root-feeding samples were collected from a rootstock trial at the UCD Oakville research station vineyard in Napa County, which had previously been sampled in 2006 and 2007. Root-feeding samples were also collected from commercial vineyards in Napa and Sonoma counties and UCD vineyards. All samples were tested and genotyped using simple sequence repeat markers, and the genetic structure of the populations was analyzed. The results identified four genetically distinct populations of phylloxera in California, which were named Davis, Foliar, Napa1, and Napa2. Davis, Napa1, and Napa2 were composed of root-feeding samples. Multilocus genotypes with identical DNA-fingerprint profiles were detected in the 2006 to 2007 samples from the Oakville research station. More genetic divergence was observed in the Davis, Napa1, and Napa2 populations, with evidence for sexual reproduction between members of Napa1 and Napa2. The Foliar population consisted of only foliar-feeding samples with multilocus genotypes that were not detected prior to 2009; asexual reproduction was clearly the primary reproductive mode.

Grape phylloxera (Daktulosphaira vitifoliaeFitch) in Argentina: ecological associations to diversity, population structure and reproductive mode

“…As previously found in other regions (Vorwerk and Forneck , , Islam et al , Forneck et al , Riaz et al ), the parthenogenetic nature of the insect in Argentina is confirmed by P sex values, the excess of heterozygous individuals and the significant deviations from the Hardy–Weinberg equilibrium. The possible occurrence, however, of sporadic sexual reproduction cannot be discarded.…”

First European leaf-feeding grape phylloxera (Daktulosphaira vitifoliae Fitch) survey in Swiss and German commercial vineyards

“…The likely patterns of the introductions of phylloxera into worldwide viticulture regions from its native habitat have Table 2 Genetic diversity parameters for grape phylloxera populations obtained in 9 Swiss (CH) and German (DE) regions been extensively analyzed by different authors using diverse genetic markers, including mitochondrial (Downie 2002) and nuclear polymorphisms (Forneck et al 2000;Lund et al 2017;Riaz et al 2017). Whereas phylloxera populations from Vitis species like V. vulpina and V. arizonica are suggested to be the more likely source of introductions into viticulture regions like California (USA), South Africa, Australia, New Zealand and South America (Arancibia et al 2018;Downie 2002;Lund et al 2017), there is a general agreement that all European phylloxera introductions are likely to come from northeastern American populations, where V. riparia dominates (Downie 2002).…”

“…A set of seven highly polymorphic SSR markers (Phy_III_55, Phy_III_30, Phy_III_36, Dvit6, DV4, DV8 and DVSSR4 (Forneck et al 2017a)) were selected and analyzed in the 335 phylloxera samples. Polymerase chain reaction (PCR), separation of fragments and allele calling was performed following the procedures detailed in Riaz et al (2017) and Forneck et al (2017a).…”

Population Structure, Diversity and Reproductive Mode of the Grape Phylloxera (Daktulosphaira vitifoliae) across Its Native Range

“…Foliar phylloxera has been rare in California, until the discovery of a widespread outbreak of leaf-galling phylloxera that occurred in grape rootstock nursery plantings in Yolo and Solano counties. One hundred and twenty-two of the 170 leaf-galling phylloxera samples tested in a previous study [ 32 ] were determined to be the same clone, represented in this study by the WEO4802 sample; the remaining samples were closely related. STRUCTURE analysis determined that the WEO4802 sample was a mixture of the V .…”