Quantitative trait loci affecting pathogen resistance and ripening of grapevines.

Grapevines (Vitis vinifera L.) form the basis of viticulture, and are susceptible to diseases such as downy mildew (Plasmopara viticola) and powdery mildew (Erysiphe necator). Therefore, successful viticulture programs require the use of pesticides. Breeding for resistance is the only eco-friendly solution. Marker-assisted selection is currently widely used for grapevine breeding. Consequently, traits of interest must be tagged with molecular markers linked to quantitative trait loci (QTL). We herein present our findings regarding genetic mapping and QTL analysis of resistance to downy and powdery mildew diseases in the progenies of the GF.GA-47-42 ('Bacchus' × 'Seyval') × 'Villard blanc' cross. Simple sequence repeats and single nucleotide polymorphisms of 151 individuals were analyzed. A map consisting of 543 loci was screened for QTL analyses based on phenotypic variations observed in plants grown in the field or under controlled conditions. A major QTL for downy mildew resistance was detected on chromosome 18. For powdery mildew resistance, a QTL was identified on chromosome 15. This QTL was replaced by a novel QTL on chromosome 18 in 2003 (abnormally high temperatures) and 2004. Subsequently, both QTLs functioned together. Additionally, variations in the timing of the onset of veraison, which is a crucial step during grape ripening, were studied to identify genomic regions affecting this trait. A major QTL was detected on linkage group 16, which was supplemented by a minor QTL on linkage group 18. This study provides useful information regarding novel QTL-linked markers relevant for the breeding of disease-resistant grapevines adapted to current climatic conditions.

Alterations in grapevine leaf metabolism upon inoculation with Plasmopara viticola in different time-points.

Grapevines are easily infected by plant pathogens. It was found that resistant grapevines induce a wide range of phenolics upon the pathogen-infection. In this study in order to gain insight into these processes in different time-points the metabolic changes during the interaction of two grapevine cultivars, 'Regent' (resistant) and 'Trincadeira' (susceptible), with the downy mildew pathogen (Plasmopara viticola) were investigated. Nuclear magnetic resonance (NMR) spectroscopy on leaf extracts was used at several time points after experimental inoculation. A wide range of metabolites were identified using various two-dimensional (2D)-NMR techniques. Multivariate data analysis characterized both the resistant and the susceptible cultivars and their response against the pathogen. Metabolites responsible for their discrimination were identified as a fertaric acid, caftaric acid, quercetin-3-O-glucoside, linolenic acid, and alanine in the resistant cultivar 'Regent', while the susceptible 'Trincadeira' showed higher levels of glutamate, succinate, ascorbate and glucose. This study portrays the analytical capability of NMR spectroscopy and multivariate data analyses methods for the metabolic profiling of plant samples. The results obtained will underline the role of phenylpropanoids and flavonoids in resistance against biotic stresses which in turn provides a firm platform for the metabolic engineering of grapevine cultivars with higher resistance towards pathogens.

Cultivar-specific kinetics of gene induction during downy mildew early infection in grapevine.

The oomycete pathogen Plasmopara viticola (Berk. et Curt.) Berl. et de Toni is the causing agent of the destructive downy mildew disease in grapevine. Despite the advances towards elucidation of grapevine resistance mechanisms to downy mildew, increased knowledge of the biological and genetic components of the pathosystem is important to design suitable breeding strategies. Previously, a cDNA microarray approach was used to compare two Vitis vinifera genotypes Regent and Trincadeira (resistant and susceptible to downy mildew, respectively) in field conditions. The same cDNA microarray chip was used to confirm field-based results and to compare both genotypes under greenhouse conditions at 0, 6, and 12 h post-inoculation with P. viticola. Results show that when comparing both cultivars after pathogen inoculation, there is a preferential modulation of several defense, signaling, and metabolism associated transcripts in Regent. Early transcriptional changes are discussed in terms of genetic background and resistance mechanism. This study is the first to directly compare resistant and susceptible cultivars responses as early as 6 hpi with P. viticola, providing several candidate genes potentially related to the expression of resistance traits.

NMR metabolic fingerprinting based identification of grapevine metabolites associated with downy mildew resistance.

Grapevine (Vitis vinifera ssp. vinifera L.) and grapes have been extensively studied due to their numerous nutritional benefits and health affecting activities. In this study, metabolite fingerprinting of crude leaf extracts, based on (1)H nuclear magnetic resonance (NMR) spectroscopy and multivariate data analyses, has been used for the metabolic characterization of six different grapevine cultivars including downy and powdery mildew resistant 'Regent' and susceptible 'Lemberger' among others. Several two-dimensional (2D)-NMR techniques were also employed leading to the identification of a number of different types of compounds. Principal component analysis (PCA), hierarchical cluster analysis (HCA), and partial least-squares-discriminant analysis (PLS-DA) of the processed (1)H NMR data revealed clear differences among the cultivars. Metabolites responsible for the discrimination in different grapevine cultivars belong to major classes, that is, organic acids, amino acids, carbohydrates, phenylpropanoids and flavonoids. A differentiation of the cultivars based on their resistance to downy mildew infection was also achieved, and metabolites associated with this trait, namely, quercetin-3-O-glucoside and a trans-feruloyl derivative, were identified. On the basis of these results, the distribution of different plant metabolites among the different grapevine cultivars is presented.

Phylogenetic analysis of Fosterella L.B. Sm. (Pitcairnioideae, Bromeliaceae) based on four chloroplast DNA regions.

The about 31 species of Fosterella L.B. Sm. (Bromeliaceae) are terrestrial herbs with a centre of diversity in the central South American Andes. To resolve infra- and intergeneric relationships among Fosterella and their putative allies, we conducted a phylogenetic analysis based on sequence data from four chloroplast DNA regions (matK gene, rps16 intron, atpB-rbcL and psbB-psbH intergenic spacers). Sequences were generated for 96 accessions corresponding to 60 species from 18 genera. Among these, 57 accessions represented 22 of the 31 recognized Fosterella species and one undescribed morphospecies. Maximum parsimony and Bayesian inference methods yielded well-resolved phylogenies. The monophyly of Fosterella was strongly supported, as was its sister relationship with a clade comprising Deuterocohnia, Dyckia and Encholirium. Six distinct evolutionary lineages were distinguished within Fosterella. Character mapping indicated that parallel evolution of identical character states is common in the genus. Relationships between species and lineages are discussed in the context of morphological, ecological and biogeographical data as well as the results of a previous amplified fragment length polymorphism (AFLP) study.

AFLP analysis of genetic relationships in the genus Fosterella L.B. Smith (Pitcairnioideae, Bromeliaceae).

The neotropical genus Fosterella L.B. Smith (Pitcairnioideae, Bromeliaceae) comprises about 30 species, with a centre of diversity in semiarid to humid habitats of the Andean slopes and valleys of Bolivia. Morphologic differentiation of species is difficult because of a paucity of diagnostic characters, and little is known about the infrageneric phylogeny. Here, we present the results of an amplified fragment length polymorphism (AFLP) analysis of 77 Fosterella specimens, covering 18 recognized species and 9 as-yet undescribed morphospecies. Eight primer combinations produced 310 bands, which were scored as presence/absence characters. Neighbour-joining tree reconstruction revealed 12 clusters (A-L) with various levels of support. Well-supported species groups were also recovered by a principal coordinates analysis. With few exceptions, morphologically defined species boundaries were confirmed by the molecular data. Phylogenetic relationships between species groups remained ambiguous, however, because of short internal branch lengths. The AFLP data were complemented by a survey of the leaf anatomy of 19 Fosterella species. Species concepts and assemblages are discussed in the context of molecular, morphologic, anatomic, ecologic, and biogeographic data. The data suggest that accidental long-distance dispersal and founder events have been important for Fosterella speciation.