Variety-specific response of wheat (Triticum aestivum L.) leaf mitochondria to drought stress

Abstract

The main objective of the present work was to examine leaf respiratory responses to dehydration and subsequent recovery in three varieties of winter wheat (Triticum aestivum L.) known to differ in their level of drought tolerance. Under dehydration, both total respiration and salicylhydroxamic acid (SHAM)-resistant cytochrome (Cyt) pathway respiration by leaf segments decreased significantly compared with well-watered plants. This decrease was more pronounced in the drought-sensitive Sadovo and Prelom genotypes. In contrast, the KCN-resistant SHAM-sensitive alternative (Alt) pathway became increasingly engaged, and accounted for about 80% of the total respiration. In the drought-tolerant Katya variety, increased contribution of the Alt pathway was accompanied by a slight decrease in Cyt pathway activity. Respiration of isolated leaf mitochondria also showed a variety-specific drought response. Mitochondria from drought-sensitive genotypes had low oxidative phosphorylation efficiency after dehydration and rewatering, whereas the drought-tolerant Katya mitochondria showed higher phosphorylation rates. Morphometric analysis of leaf ultrastructure revealed that mitochondria occupied approximately 7% of the cell area in control plants. Under dehydration, in the drought-sensitive varieties this area was reduced to about 2.0%, whereas in Katya it was around 6.0%. The results are discussed in terms of possible mechanisms underlying variety-specific mitochondrial responses to dehydration.

Drought stress and carbon assimilation in a warming climate: Reversible and irreversible impacts

“…The response of different genotypes of the same crop species to drought or heat periods may vary in wide range (Vassileva et al, 2009(Vassileva et al, , 2011(Vassileva et al, , 2012Erice et al, 2010Erice et al, , 2011Yin et al, 2010 ;Parry et al, 2011;Prior et al, 2011;Cao et al, 2014 ;Habash et al, 2014;Topbjerg et al, 2014;Acuna-Galinda et al, 2015 ;Lopes et al, 2015;Wani et al, 2015;Wehner et al, 2015). This is the basis for breeding of crop varieties with a better performance under abiotic stresses.…”

“…Most of the protective enzymes and solutes mentioned above are not directly involved in photosynthesis, but are relevant for maintaining the metabolism in chloroplasts as well as in other subcellular compartments in a functional state (Vassileva et al, 2009;Grigorova et al, 2012). Such protective mechanisms are relevant for stress phases, but may also be relevant for the performance of plants after a stress period by influencing the velocity and the degree of recovery (Gallé and Feller, 2007;Gallé et al, 2007;Vassileva et al, 2011).…”

“…The decrease in net CO2 assimilation during a heat period is initially reversible, but depending on the leaf temperature reached and the duration of the stress it may be only partially reversible or even irreversible (Haldimann andFeller, 2004, 2005;Haldimann et al, 2008;Vassileva et al, 2009;Cano et al, 2014;Zwicke et al, 2015). The performance of a crop depends on the processes during a stress period as well as during the pre-stress phase and during a subsequent recovery phase after the stress period.…”

“…Therefore the integral performance during the whole season is relevant for a comprehensive evaluation of a species or of a genotype. Net photosynthesis does not only depend on photosynthetic electron transport and Calvin cycle activity, since carbon losses via decarboxylation processes also contribute to the overall performance (Wingler et al, 1999;Haupt-Herting et al, 2001;Noctor et al, 2002;Bai et al, 2008;Rivero et al, 2009;Vassileva et al, 2009Vassileva et al, , 2011. The impact of heat and drought on respiration is also crucial for the carbon balance and should be considered when comparing genotypes (Flexas et al, 2006;Vassileva et al, 2011).…”

Drought, high temperature, and their combination affect ultrastructure of chloroplasts and mitochondria in wheat (Triticum aestivumL.) leaves

“…Plant stress responses to individual and combined application of drought and high temperature are often species specific, but there are also differences among varieties and cultivars within a species Demirevska et al 2008;Vassileva et al 2011). Changes in water and temperature regimes affect plant structure and functions differently, as drought-sensitive cultivars are more vulnerable to stress damages than drought-tolerant cultivars (Ristic and Cass 1991;Vassileva et al 2009). The tolerant cultivars show an enhanced ability to recover after stress exposure.…”