The grapevine reproductive cycle has a number of unique features. Inflorescences develop from lateral meristems (anlagen) in latent buds during spring and summer and enter a dormant state at a very immature stage before completing development and producing flowers and berries the following spring. Lateral meristems are unique structures derived from the shoot apical meristem and can either develop into an inflorescence or a tendril. How the grapevine plant controls these processes at the molecular level is not understood, but some progress has been made by isolating and studying the expression of flowering genes in wild-type and mutant grapevine plants. Interestingly, a number of flowering genes are also expressed during berry development. This paper reviews the current understanding of the genetic control of grapevine flowering and the impact of viticulture management treatments and environmental variables on yield. While the availability of the draft genome sequence of grapevine will greatly assist future molecular genetic studies, a number of issues are identified that need to be addressed--particularly rapid methods for confirming gene function and linking genes to biological processes and traits. Understanding the key interactions between environmental factors and genetic mechanisms controlling the induction and development of inflorescences, flowers, and berries is also an important area that requires increased emphasis, especially given the large seasonal fluctuations in yield experienced by the crop and the increasing concern about the effect of climate change on existing wine-producing regions.

Phenol extraction of proteins is an alternative method to classical TCA-acetone extraction. It allows efficient protein recovery and removes nonprotein components in the case of plant tissues rich in polysaccharides, lipids, and phenolic compounds. We present here a tried and tested protocol adapted for two dimensional electrophoresis (2-DE) and further proteomic studies. After phenol extraction, proteins are precipitated with ammonium acetate in methanol. The pelleted proteins are then resuspended in isoelectric focusing buffer, and the protein concentration is measured with a modified Bradford assay prior to electrophoresis. The important points for successful use of this protocol are (1) keeping samples at very low temperature during the first step and (2) careful recovery of the phenolic phase after the centrifugations, which are major features of this protocol.

Numerous studies have revealed the extent of genetic and phenotypic variation between both species and cultivars of tomato. Using a series of tomato lines resulting from crosses between a cherry tomato and three independent large fruit cultivar (Levovil, VilB, and VilD), extensive profiling of both central primary metabolism and volatile organic components of the fruit was performed. In this study, it was possible to define a number of quantitative trait loci (QTLs) which determined the levels of primary metabolites and/or volatile organic components and to evaluate their co-location with previously defined organoleptic QTLs. Correlation analyses between either the primary metabolites or the volatile organic compounds and organoleptic properties revealed a number of interesting associations, including pharmaceutical aroma–guaiacol and sourness–alanine, across the data set. Considerable correlation within the levels of primary metabolites or volatile organic compounds, respectively, were also observed. However, there was relatively little association between the levels of primary metabolites and volatile organic compounds, implying that they are not tightly linked to one another. A notable exception to this was the strong association between the levels of sucrose and those of a number of volatile organic compounds. The combined data presented here are thus discussed both with respect to those obtained recently from wide interspecific crosses of tomato and within the framework of current understanding of the chemical basis of fruit taste.

SUMMARYA grapevine model system is described that is suitable for rapid forward and reverse genetic studies in small controlled environments. It is based on the Vvgai1 mutant allele that confers a dwarf stature, short generation cycles and continuous flowering ('microvine'). Black and white berry microvine genotypes were developed that can be transformed by Agrobacterium tumefaciens. Near-homozygous lines were created for efficient bi-allelic single nucleotide polymorphism (SNP) marker mapping and mutagenesis studies. A genetic mapping strategy based on picovine-derived microvine progeny populations was used to rapidly phenotype and map the flower sex and fleshless berry loci and identify a new lethal recessive locus, Vvlrl1. The microvine provides a unique model system for rapid genetic studies of grapevine by changing the perennial long life cycle of the plant to one with features and advantages similar to an annual plant.

Tomato texture is one of the critical components for the consumer's perception of fruit quality. Texture is a complex character composed of several attributes that are difficult to evaluate and which change during fruit ripening. This study investigated the texture of tomato fruits at the rheological, sensory, morphological, and genetic levels, and attempted to correlate several parameters. Analyses were performed on tomato fruits from introgressed lines carrying quantitative trait loci (QTLs) associated with texture traits localized on different chromosomes, in two genetic backgrounds. Rheological measurements were used to determine resistance to deformation and fruit elasticity. Sensory analysis was used to assess flesh firmness, juiciness, mealiness, and skin toughness. Image analysis was used to study fruit morphology and to define the cellular structure and heterogeneity of the pericarp. A highly significant correlation was observed between instrumental and sensory firmness. Moreover, correlations were also established between some texture traits and parameters of the pericarp cellular structure. Compared with QTLs detected in a previous study, the phenotypic effects expected for mealiness were confirmed in all lines, whereas, for firmness, they were not confirmed. Significant interactions between QTL and genetic background were observed for several traits. In addition, kinetic analysis showed that differences in firmness occurred from the early stages of fruit development. These results provide both a broad description of texture components and preliminary information to understand their genetic control.

The effect of a gene involved in the variation of a quantitative trait may change due to epistatic interactions with the overall genetic background or with other genes through digenic interactions. The classical populations used to map quantitative trait loci (QTL) are poorly efficient to detect epistasis. To assess the importance of epistasis in the genetic control of fruit quality traits, we compared 13 tomato lines having the same genetic background except for one to five chromosome fragments introgressed from a distant line. Six traits were assessed: fruit soluble solid content, sugar content and titratable acidity, fruit weight, locule number and fruit firmness. Except for firmness, a large part of the variation of the six traits was under additive control, but interactions between QTL leading to epistasis effects were common. In the lines cumulating several QTL regions, all the significant epistatic interactions had a sign opposite to the additive effects, suggesting less than additive epistasis. Finally the re-examination of the segregating population initially used to map the QTL confirmed the extent of epistasis, which frequently involved a region where main effect QTL have been detected in this progeny or in other studies.

We developed primers for the amplification of 24 polymorphic nuclear microsatellites in apricot (Prunus armeniaca L.). Thirteen loci originated from three genomic libraries enriched for TC, TG and AAG motifs. Eight loci were developed from three fruit EST (Expressed‐Sequence‐Tag) libraries and three from a leaf cDNA microsatellite‐enriched library. There were up to nine alleles per polymorphic locus in 12 different cultivars. No difference in allele numbers were shown between cDNA and genomic‐source loci. Mean expected heterozygosity was 0.65 (range: 0.15–0.87). Mendelian segregation was confirmed for all loci. These markers should be helpful for diversity studies, genome mapping and cultivar identification in apricot and related species.

The efficiency of marker-assisted backcross for the introgression of a quantitative trait locus (QTL) from a donor line into a recipient line depends on the stability of QTL expression. QTLs for six quality traits in tomato (fruit weight, firmness, locule number, soluble solid content, sugar content and titratable acidity) were studied in order to investigate their individual effect and their stability over years, generations and genetic backgrounds. Five chromosome regions carrying fruit quality QTLs were transferred following a marker-assisted backcross scheme from a cherry tomato line into three modern lines with larger fruits. Three sets of genotypes corresponding to three generations were compared: (1) an RIL population, which contained 50% of each parental genome, (2) three BC3S1 populations which segregated simultaneously for the five regions of interest but were almost fully homozygous for the recipient genome on the eight chromosomes carrying no QTL and (3) three sets of QTL-NILs (BC3S3 lines) which differed from the recipient line only in one of the five regions. QTL detection was performed in each generation, in each genetic background and during 2 successive years for QTL-NILs. About half of the QTLs detected in QTL-NILs were detected in both years. Eight of the ten QTLs detected in RILs were recovered in the QTL-NILs with the genetic background used for the initial QTL mapping experiment, with the exception of two QTLs for fruit firmness. Several new QTLs were detected. In the two other genetic backgrounds, the number of QTLs in common with the RILs was lower, but several new QTLs were also detected in advanced generations.