BackgroundThe increasing temperature associated with climate change impacts grapevine phenology and development with critical effects on grape yield and composition. Plant breeding has the potential to deliver new cultivars with stable yield and quality under warmer climate conditions, but this requires the identification of stable genetic determinants. This study tested the potentialities of the microvine to boost genetics in grapevine. A mapping population of 129 microvines derived from Picovine x Ugni Blanc flb, was genotyped with the Illumina® 18 K SNP (Single Nucleotide Polymorphism) chip. Forty-three vegetative and reproductive traits were phenotyped outdoors over four cropping cycles, and a subset of 22 traits over two cropping cycles in growth rooms with two contrasted temperatures, in order to map stable QTLs (Quantitative Trait Loci).ResultsTen stable QTLs for berry development and quality or leaf area were identified on the parental maps. A new major QTL explaining up to 44 % of total variance of berry weight was identified on chromosome 7 in Ugni Blanc flb, and co-localized with QTLs for seed number (up to 76 % total variance), major berry acids at green lag phase (up to 35 %), and other yield components (up to 25 %). In addition, a minor QTL for leaf area was found on chromosome 4 of the same parent. In contrast, only minor QTLs for berry acidity and leaf area could be found as moderately stable in Picovine. None of the transporters recently identified as mutated in low acidity apples or Cucurbits were included in the several hundreds of candidate genes underlying the above berry QTLs, which could be reduced to a few dozen candidate genes when a priori pertinent biological functions and organ specific expression were considered.ConclusionsThis study combining the use of microvine and a high throughput genotyping technology was innovative for grapevine genetics. It allowed the identification of 10 stable QTLs, including the first berry acidity QTLs reported so far in a Vitis vinifera intra-specific cross. Robustness of a set of QTLs was assessed with respect to temperature variation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0588-0) contains supplementary material, which is available to authorized users.

<p class="Abstract" style="text-align: justify;"><strong>Aim:</strong> In the long term, genetic improvement is one of the major strategies to support sustainable wine production in a changing climate. Over the past 5 years, we have developed an interdisciplinary research program that aimed to: i) characterize the impact of temperature increase sensed by the entire plant or individual bunches on the development and functioning of the plant, ii) identify the physiological and molecular mechanisms regulating the response of vegetative and reproductive development to heat stress and iii) develop tools to map quantitative trait loci (QTLs) of plant and berry development in duly controlled, stable, and contrasting environmental conditions.</p><p class="Abstract" style="text-align: justify;"><strong>Methods and results:</strong> Performing high-throughput genomic analyses combined with the use of innovative experimental designs (fruiting cuttings, microvines, single berry sampling) was critical to decipher the ecophysiological and molecular mechanisms involved in the vine response to high temperature.</p><p class="Abstract" style="text-align: justify;"><strong>Conclusion:</strong> Warming promotes vegetative growth and hampers plant carbon balance, disturbing flower set and young berry development. High temperatures modify primary and secondary fruit metabolisms, desynchronizing sugar and organic acid metabolisms and delaying sugar and polyphenol accumulation during ripening. The study of day and night transcriptomic and proteomic signatures associated with heat highlighted key players of the response to temperature in the fruit. </p><p class="Abstract" style="text-align: justify;"><strong>Significance and impact of the study:</strong> Capitalizing on this knowledge, a new program is being proposed for the selection of cultivars limiting the accumulation of sugars in the berry while maintaining other qualitative compounds.</p>

Grapevine (Vitis) is considered to be one of the major fruit crops in the world based on hectares cultivated and economic value. Grapes are used not only for wine but also for fresh fruit, dried fruit, and juice production. Wine is by far the major product of grapes, and the focus of this chapter is on wine grape cultivars. Grapevine cultivars of Vitis vinifera L. have a reputation for producing premium quality wines. These premium quality wines are produced from a small number of cultivars that enjoy a high level of consumer acceptance and are firmly entrenched in the market place because of varietal name branding and the association of certain wine styles and regions with specific cultivars. In light of this situation, grapevine improvement by a transgenic approach is attractive when compared to a classical breeding approach. The transfer of individual traits as single genes with a minimum disruption to the original genome would leave the traditional characteristics of the cultivar intact. However, a reliable transformation system is required for a successful transgenic approach to grapevine improvement. There are three criteria for achieving an efficient Agrobacterium-mediated transformation system: (1) the production of highly regenerative transformable tissue, (2) optimal cocultivation conditions for both grapevine tissue and Agrobacterium, and (3) an efficient selection regime for transgenic plant regeneration. In this chapter, we describe a grapevine transformation system that meets these criteria. We also describe a protocol for the production of transformed roots suitable for functional gene studies and for the production of semi-transgenic grafted plants.

Aim: In the long term, genetic improvement is one of the major strategies to support sustainable wine production in a changing climate. Over the past 5 years, we have developed an interdisciplinary research program that aimed to: i) characterize the impact of temperature increase sensed by the entire plant or individual bunches on the development and functioning of the plant, ii) identify the physiological and molecular mechanisms regulating the response of vegetative and reproductive development to heat stress and iii) develop tools to map quantitative trait loci (QTLs) of plant and berry development in duly controlled, stable, and contrasting environmental conditions.Methods and results: Performing high-throughput genomic analyses combined with the use of innovative experimental designs (fruiting cuttings, microvines, single berry sampling) was critical to decipher the ecophysiological and molecular mechanisms involved in the vine response to high temperature.Conclusion: Warming promotes vegetative growth and hampers plant carbon balance, disturbing flower set and young berry development. High temperatures modify primary and secondary fruit metabolisms, desynchronizing sugar and organic acid metabolisms and delaying sugar and polyphenol accumulation during ripening. The study of day and night transcriptomic and proteomic signatures associated with heat highlighted key players of the response to temperature in the fruit. Significance and impact of the study: Capitalizing on this knowledge, a new program is being proposed for the selection of cultivars limiting the accumulation of sugars in the berry while maintaining other qualitative compounds.