Physiological and biochemical changes attenuate the effects of drought on the Cerrado species Vatairea macrocarpa (Benth.) Ducke

Abstract

Drought is considered the main abiotic stress because it influences the distribution of plant species and limits the productivity of ecosystems. The aim of this study was to evaluate the effects of drought on physiological and biochemical parameters during the initial development of Vatairea macrocarpa, a native cerrado species. Plants were subjected to daily watering (control); suppression of watering during 90 days with field capacity (fc) 50% and 25% and then followed by rewatering. Relative leaf water content (RWC), gas exchange, photosynthetic pigments content, carbohydrate and amino acids content, antioxidant activities and growth were recorded. The RWC decreased according to the soil water restriction, causing reduction in stomatal conductance and decrease of 76.4% in net photosynthesis in plants submitted to 25% fc. Water restriction decreased the chlorophyll content, however increased carotenoid content and also improved the antioxidant activities of superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT). In addition, high levels of sugars (sucrose, raffinose) and amino acids (proline, tryptophan, valine, glutamine and GABA) were detected in drought stressed plants, contributing to osmoregulation and as sources of carbon and nitrogen after rehydration. Decreases in carbon assimilation promoted a reduction of the leaf area, however an increase in the root surface area was observed. After rewatering, the analized parameters became similar to the control plants indicating that the severe water stress did not impair the survival of young plants. Instead, adjustments were made to protect them against drought such as the maintenance of the assimilatory metabolism at minimal levels.

Expression of dehydrin and antioxidant genes and enzymatic antioxidant defense under drought stress in wild relatives of wheat

“…Since the detected enzyme activity is a consequence of both synthesis and decomposition, any reduction in net SOD under stress could be attributed to either the enhanced degradation or reduced synthesis of the enzyme [58]. GPX is another important enzyme that plays a key role in protecting against stresses through the removal of H 2 O 2 in chloroplasts and biosynthesizing lignin [59,60]. In this research, the maximum GPX activity occurred in Ae.…”

Biochemical and morphophysiological strategies of Myracrodruon

“…2016). The reduction in chlorophyll content during water restriction (Table 1) could be considered as an adaptive mechanism for low-energy absorption because the excess energy stored in chlorophyll molecules in their triplet state can be transferred to oxygen molecules and lead to the formation of singlet oxygen ( 1 O2), which is a ROS that can cause membrane-lipid peroxidation (Vieira et al 2017).…”

“…Under adverse environmental conditions, plants activate enzymatic and non-enzymatic antioxidant defense systems to avoid a severe damage caused by oxidizing molecules to their structures. Enzymatic antioxidants mainly consist of SOD, APX, CAT, and peroxidase whereas non-enzymatic antioxidants consist of glutathione, ascorbic acid, and carotenoids (Vieira et al 2017). Although water restriction led to increased antioxidant enzyme activities, reductions in enzyme activities may occur during senescence as observed in M. urundeuva control plants at the end of the experimental period (Table 2).…”

“…Other mechanisms used by plants under conditions of water scarcity are variations in epicuticular wax composition, stomatal density, water storage tissues, and the presence of trichomes (Barros and Soares 2013, Santos et al 2014, Maia et al 2017, Meira et al 2017 Under conditions of water deficit, plants adjust their sugar, protein, amino acid, chlorophyll, and carotenoid content in order to protect cells. For example, sugars and amino acids may affect osmotic adjustment by acting as osmoprotectants or serve as signaling molecules to prevent oxidative stress (Nishizawa et al 2008, Vieira et al 2017. Plant responses to various environmental factors are related to plants ability to control oxidants content, which is highly correlated with their tolerance to environmental stresses (Munné-Bosch et al 2013).…”

Mechanisms of desiccation tolerance in the bromeliad Pitcairnia burchellii Mez: biochemical adjustments and structural changes

“…In leaves and rhizomes of P. burchellii, an increase in the proline content was initiated at 30 days and maintained up to 90 days of water witholding, possibly contributing to the osmotic equilibrium, structure protection and as a source of nitrogen after rehydration (Vieira et al, 2017a). Proline acts as a nitrogen reserve for the synthesis of specific enzymes and as a molecular chaperone, stabilizing protein structures and protecting cells against ROS accumulation (Vicré et al, 2004;Krasensky and Jonak, 2012).…”