Abstract
Plants respond to drought stress through different physiological mechanisms. To highlight a specific adaptation strategy related to stem photosynthetic activity, woody tissue pigmentation was studied. In this work, 25 Vitis hybrids were studied in two experimental vineyards: one of them with sufficient water availability and the other showing drought stress. 1500 reflectance spectra of woody tissues were collected. Beside the spectral elaboration and interpretation, indexes for the pigment quantification were calculated. The content and the proportion in chlorophylls (a and b) in stems were significantly modified in response to water stress. Genotypes were classified based on their plasticity/elasticity and adaptive/susceptible behavior. The cluster analysis produced 4 main groups based on their average spectra and on the spectral variations between watered and stress conditions. The most interesting genotypes concerning this trait were pointed out. Nevertheless, this adaptation mechanism could also be due to an increased detoxification necessity related to other physiological disfunctions caused by water stress. A multi-parameter approach is encouraged for phenotyping of abiotic stress tolerant plant selection. In the next future, this work will support the release of new drought tolerant rootstocks for viticulture.
Highlights
The consequences of drought in plants are mainly due to the interlinked effects on hydraulic failure and carbon starvation (Vandegehuchte et al 2015)
A different strategy of woody tissues carbon fixation is made by corticular photosynthesis, that has been mainly documented in temperate-zone trees (Nilsen 1995; Aschan and Pfanz 2003; Cernusak and Cheesma 2015; Tikhonov et al 2017)
The photosynthetic activity of woody shoots in V. vinifera has been already demonstrated since 1971 (Kriedemann and Bottrose 1971) and the recent interpretations of the roles of corticular photosynthesis to cope drought emphasize the importance of this mechanism (Cernusak and Cheesma 2015; Vandegehuchte et al 2015)
Summary
The consequences of drought in plants are mainly due to the interlinked effects on hydraulic failure and carbon starvation (Vandegehuchte et al 2015). Stems frequently contribute to a significant proportion of the plant carbon fixation, being the primary photosynthetic organs in mostly of the desert CAM species (Nilsen 1995; Aschan and Pfanz 2003; Cernusak and Cheesma 2015). A different strategy of woody tissues carbon fixation is made by corticular photosynthesis (involving cortex of new shoots and/or ray parenchyma cells and/or bark), that has been mainly documented in temperate-zone trees (Nilsen 1995; Aschan and Pfanz 2003; Cernusak and Cheesma 2015; Tikhonov et al 2017). Stem photosynthesis allows the maintenance of physiological activity during stress; it increases the water use efficiency; it provides the carbon source for new organs; and it avoids hypoxia, raising the internal O2 concentration (Avila et al 2014; Vandegehuchte et al 2015)
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