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1. Identification of Vitis Cultivars, Rootstocks, and Species Expressing Resistance to a Planococcus Mealybug

Author

Rachel P. Naegele, Peter Cousins, and Kent M. Daane

Subjects
host plant resistance, pest management, planococcus ficus, vineyard, Science
Abstract

Mealybugs cause economic loss to vineyards through physical damage, fouling fruit and leaves with honeydew, and the transmission of viruses. Planococcus ficus is one of several mealybug species in vineyards, and one that causes economic damage over a relatively large global range. To develop novel management tools, host resistance to P. ficus, which has not previously been identified for any grape cultivars, was studied. Ten grape lines (species, cultivars, and rootstocks) were evaluated for P. ficus resistance across two separate potted plant assays. Significant differences were detected among cultivars and rootstocks in the recorded number of P. ficus juveniles, adults, and egg sacs. Cabernet Sauvignon and Chardonnay were two of the most favorable grape cultivars for mealybug population growth, whereas rootstocks IAC 572, 10-17A, and RS-3 all demonstrated some level of resistance. Southern fire ant (Solenopsis xyloni) was positively associated with mealybug populations, but did not have a negative effect on the observed presence of other arthropod species including potential predators.

Published
2020
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2. Color Intensity of the Red-Fleshed Berry Phenotype of Vitis vinifera Teinturier Grapes Varies Due to a 408 bp Duplication in the Promoter of VvmybA1

Author

Ludger Hausmann, Ulrike Braun, Erika Maul, Florian Schwander, Reinhard Töpfer, Carina Moock, Franco Röckel, and Peter Cousins

Subjects
0106 biological sciences, 0301 basic medicine, lcsh:QH426-470, Myb, Berry, 01 natural sciences, Article, anthocyanin, Anthocyanins, 03 medical and health sciences, chemistry.chemical_compound, Gene Duplication, Gene duplication, Genetics, Vitis, Allele, Promoter Regions, Genetic, Enhancer, Gene, Genetics (clinical), Plant Proteins, berry color, biology, Pigmentation, Teinturier, fungi, teinturier, food and beverages, genetic diversity, biology.organism_classification, Phenotype, grapevine, lcsh:Genetics, 030104 developmental biology, chemistry, repetitive DNA element, Glucosyltransferases, Fruit, Anthocyanin, periclinal chimera, Transcription Factors, 010606 plant biology & botany
Abstract

Grapevine (Vitis vinifera) teinturier cultivars are characterized by their typical reddish leaves and red-fleshed berries due to ectopic anthocyanin formation. Wines of these varieties have economic importance as they can be used for blending to enhance the color of red wines. The unique and heritable mutation has been known for a long time but the underlying genetic mechanism still is not yet understood. Here we describe the association of the red-fleshed berry phenotype with a 408 bp repetitive DNA element in the promoter of the VvmybA1 gene (grapevine color enhancer, GCE). Three different clones of &lsquo, Teinturier&rsquo, were discovered with two, three and five allelic GCE repeats (MybA1t2, MybA1t3 and MybA1t5). All three clones are periclinal chimeras, these clones share the same L1 layer, but have distinct L2 layers with different quantities of GCE repeats. Quantitative real time PCR and HPLC analysis of leaf and berry samples showed that the GCE repeat number strongly correlates with an increase of the expression of VvmybA1 itself and the VvUFGT gene regulated by it and the anthocyanin content. A model is proposed based on autoregulation of VvmybA1t to explain the red phenotype which is similar to that of red-fleshed apples. This study presents results about the generation and modes of action of three MybA1t alleles responsible for the red-fleshed berry phenotype of teinturier grapevines.

Published
2020
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