Abstract

High temperatures and extreme drought are increasingly more frequent in Portugal, which represents a strong threat to viticulture in certain regions of the country. These multifactorial abiotic stresses are threatening viticultural areas worldwide, and the problem can hardly be overcome only by changing cultural practices. This scenario has raised a major challenge for plant scientists to find ways to adapt existing varieties to the new conditions without loss of their characteristic flavors, yield, and associated varietal character of wines. Aragonez (syn. Tempranillo) is one such variety, widely cultivated in Portugal and Spain, with specific characteristics associated with terroir. In this context, insight into intravarietal variability to enable its exploitation for selection becomes an important tool to mitigate the effect of multifactorial stresses driven by climate changes. The present work describes an innovative selection approach: selection for abiotic stress tolerance, measured by the leaf temperature of clones under environmental conditions of drought and extreme heat. This evaluation was complemented with values of yield and quality characteristics of the must (pH, acidity, °Brix, and anthocyanins). The application of this methodology was done in an experimental population of 255 clones of Tempranillo for 3 years. The genotypes were then ranked according to their level of tolerance to abiotic stress without loss of yield/quality. To understand the differences at the transcription level that could account for such variability, several of the most tolerant and most sensitive genotypes were analyzed for key genes using reverse transcriptase–quantitative polymerase chain reaction. The results enabled the selection of a group of genotypes with increased tolerance to stress, in relation to the average of the variety, which maintained the typical must quality of Aragonez. In parallel, several transcripts previously acknowledged as markers for abiotic stress tolerance were identified in several clones and are possible targets for plant breeding and genetic modification and/or to develop screening procedures to select genotypes better adapted to the abiotic stress driven by climate change.

Highlights

  • Grapevine is one of the most economically important crop species in Portugal

  • Viticulture is highly dependent upon climatic conditions during the growing season, and wine production is being affected by climate change

  • From the results obtained from the univariate analysis (Table 1), it was possible to verify that there is significant genetic variability within the variety for the trait Surface leaf temperature (SLT) (P < 0.001)

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Summary

Introduction

Grapevine is one of the most economically important crop species in Portugal. Grapes, feeds the wine sector, highly significant for the national economy and a major export. In 2018, Portugal was the fifth wine producer in the European Union, and the 11th worldwide (International Organisation of Vine and Wine [OIV], 2018). Viticulture is highly dependent upon climatic conditions during the growing season, and wine production is being affected by climate change. Return on investment is driven by yield and its quality; it is relevant to study the impact of climate change, namely, the implications of changes in temperature levels and patterns, radiation, and water availability on those parameters. Portugal is extremely rich in autochthonous grapevine varieties with more than 250 already known and with a high level of intravarietal variability (Martins and Gonçalves, 2015)

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