Response of Mycorrhizal 'Touriga Nacional' Variety Grapevines to High Temperatures Measured by Calorespirometry and Near-Infrared Spectroscopy.

Amaia Nogales,Julio Nogales-Bueno,Augusto Peixe,Elsa F Gonçalves,Lee D Hansen,Hélia Cardoso,Hugo Ribeiro,Ana Elisa Rato,Wanda Viegas,João Lucas Coito

doi:10.3390/plants9111499

Abstract

Heat stress negatively affects several physiological and biochemical processes in grapevine plants. In this work, two new methods, calorespirometry, which has been used to determine temperature adaptation in plants, and near-infrared (NIR) spectroscopy, which has been used to determine several grapevine-related traits and to discriminate among varieties, were tested to evaluate grapevine response to high temperatures. ‘Touriga Nacional’ variety grapevines, inoculated or not with Rhizoglomus irregulare or Funneliformis mosseae, were used in this study. Calorespirometric parameters and NIR spectra, as well as other parameters commonly used to assess heat injury in plants, were measured before and after high temperature exposure. Growth rate and substrate carbon conversion efficiency, calculated from calorespirometric measurements, and stomatal conductance, were the most sensitive parameters for discriminating among high temperature responses of control and inoculated grapevines. The results revealed that, although this vine variety can adapt its physiology to temperatures up to 40 °C, inoculation with R. irregulare could additionally help to sustain its growth, especially after heat shocks. Therefore, the combination of calorespirometry together with gas exchange measurements is a promising strategy for screening grapevine heat tolerance under controlled conditions and has high potential to be implemented in initial phases of plant breeding programs.

Highlights

Grapevine (Vitis vinifera L.) is one of the most important crops worldwide with 7449 thousand hectares of cultivated area
Leaf chlorophyll content and electrolyte leakage have traditionally been used as indirect measures of heat stress tolerance in diverse plant species [33,82,83,84,85,86], as high stressful temperatures commonly lead to a decrease in the amount of photosynthetic pigments [85,87,88] and affect the integrity and functions of biological membranes, enhancing their permeability and leading to cell electrolyte leakage [9]
A major challenge to phenotyping heat stress tolerance is the selection of suitable phenotypic traits to measure

Summary

Introduction

Grapevine (Vitis vinifera L.) is one of the most important crops worldwide with 7449 thousand hectares of cultivated area. Direct negative effects of heat stress include protein denaturation and aggregation, and increased fluidity of membrane lipids, while indirect heat injuries include inactivation of enzymes in chloroplast and mitochondria, inhibition of protein synthesis, protein degradation, and loss of membrane integrity [10]. Such responses can adversely affect photosynthesis, respiration, and water relations, as well as modulate hormones and primary and secondary metabolite levels [9]

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