Phytoprostanes and Phytofurans—Oxidative Stress and Bioactive Compounds—in Almonds are Affected by Deficit Irrigation in Almond Trees

Abstract

Almonds have gained consumers’ attention due to their health benefits (they are rich in bioactive compounds) and sensory properties. Nevertheless, information about phytoprostanes (PhytoPs) and phytofurans (PhytoFs) (new plant markers of oxidative stress and compounds with biological properties for human health) in almonds under deficit irrigation is scarce or does not exist. These compounds are plant oxylipins synthesized by the oxidation of α-linolenic acid (ALA). Besides, they are biomarkers of plant oxidative degradation and biologically active molecules involved in several plant defense mechanisms. hydroSOStainable or hydroSOS mean plant foods made from from plants under controlled water stress. Almonds are a good source of polyunsaturated fatty (PUFAs) acids, including a high content of ALA. This paper aimed to describe the influence of diverse irrigation treatments on in vitro anti-oxidant activity (AAc) and total phenolic content (TPC), as well as on the level of ALA, PhytoP, and PhytoF in “Vairo” almonds. The AAc and TPC were not affected by the irrigation strategy, while the in vivo oxidative stress makers, PhytoPs and PhytoFs, exhibited significant differences in response to water shortage. The total PhytoP and PhytoF contents ranged from 4551 to 8151 ng/100 g dry weight (dw) and from 33 to 56 ng/100 g dw, respectively. The PhytoP and PhytoF profiles identified in almonds showed significant differences among treatments. Individual PhytoPs and PhytoFs were present above the limit of detection only in almonds obtained from trees maintained under deficit irrigation (DI) conditions (regulated deficit irrigation, RDI, and sustained deficit irrigation, SDI) but not in control almonds obtained from fully irrigated trees. Therefore, these results confirm PhytoPs and PhytoFs as valuable biomarkers to detect whether an almond-based product is hydroSOStainable. As a final conclusion, it can be stated that almond quality and functionality can be improved and water irrigation consumption can be reduced if controlled DI strategies are applied in almond orchards.

Metabolomics-Based Evaluation of Crop Quality Changes as a Consequence of Climate Change

“…In turn, as ABA participates in fruit ripening, it is expected that its induction under drought or salt stress will affect the fruit metabolic composition, in particular the sugar and anthocyanin content [14,86,135] (Figure 2). For these reasons, several irrigation strategies have been essayed to obtain high-quality fruits without a great loss in crop yield while optimizing the water use [62,81,136]. As the response to abiotic stress is commonly species-and cultivar-dependent, the stress impacts on fruit metabolism must be monitored individually to obtain the best performance [81].…”

“…For these reasons, several irrigation strategies have been essayed to obtain high-quality fruits without a great loss in crop yield while optimizing the water use [ 62 , 81 , 136 ]. As the response to abiotic stress is commonly species- and cultivar-dependent, the stress impacts on fruit metabolism must be monitored individually to obtain the best performance [ 81 ].…”

“…In contrast, in almonds, the total content of phytoprostanes increased as stress increased, being higher under severe stress, while the total phytofuranes were higher under moderate stress than under severe stress [ 62 ]. In this sense, phytoprostanes and phytofuranes can be considered as potential osmotic stress biomarkers.…”

“…Therefore, the effects on the total content of these beneficial compounds depend on the species. Moreover, when individual analyses of individual compounds are performed, the obtained profiles depend on the severity of the stress; therefore, they can be used as markers to determine which kind of stress the plant has suffered [ 62 ]. For example, the most abundant phytoprostanes in pistachios increased, as did their total content, under moderate stress, while less abundant phytoprostanes were highest in plants under full irrigation regimes [ 61 ].…”

METLIN Neutral Loss Database Enhances Similarity Analysis

“…Overall, METLIN-NL empirically derived data will enable new types of analyses facilitating more rapid identification of unknown compounds via both fragment ion and neutral loss similarity searching. 2 Both biologists and chemists will be able applying METLIN-NL to the structure elucidation of unknowns derived from animals, 19 plants, 14,20 or microbiota 21 ; and METLIN-NL can also be used as a resource for identifying unexpected synthetic chemical or enzymatically modified drug products (e.g. pharmaceuticals 22 ) as it is populated with both biological and chemical entities.…”