Editorial: Recent Advances and Approaches in the Application of Elicitors to Enhance Resistance Mechanisms in Fresh Produce

Ghulam Khaliq^1*, Sajid Ali², Nigel Gapper³ and Silvana Nicola⁴

• ¹Lasbela University of Agriculture, Water and Marine Sciences, Pakistan
• ²Bahauddin Zakariya University, Pakistan
• ³The New Zealand Institute for Plant and Food Research Ltd, New Zealand
• ⁴University of Turin, Italy

Fruits and vegetables have appreciable amounts of flavonoids, anthocyanins, tannins, vitamin C and other phytochemicals. They contain health promising compounds such as anti-inflammatory, anti-oxidative, radical-scavenging activity and gastroprotective properties (Liu, 2013). However, fruits and vegetables are highly perishable food items that cannot store for very long time. Keeping losses to a minimum before and after harvesting is, therefore, a key challenge, not only from an economic standpoint but from an environmental one as well. Pre-harvest and postharvest abiotic stresses remain the greatest challenge to maintain quality and increase production of highly perishable crops worldwide (Suwannachot et al.). These abiotic stresses have the potential to cause a series of morphological, physiological, biochemical, and molecular changes that adversely affect plant growth, productivity, and quality attributes (Ali et al., 2022). Abiotic stresses impact not only the productivity, and nutritional characteristics of perishables, but the quality and shelf-life, and these changes can cause huge losses to growers, industries, and retailers.Increasing concerns over the use of chemicals for maintaining the postharvest quality of fresh produce and unacceptability in terms of public and environmental risk have favoured the introduction of elicitors (Raffo and Paoletti). In recent years, the use of physical, biological, and/or chemical elicitors to induce natural resistance in horticultural crops has drawn more attention, and is now regarded as a preferred quality management method. This research topic was launched to gather novel information on the abiotic stress responses in horticultural plants from the field to the consumer. The articles included in this research topic examined the activation of resistance mechanisms through physical or chemical treatments , and explored the efficacy of plant elicitors treatments for reducing oxidative damage as plants demonstrated adaptive responses when exposed to elicitors.
Fruits and vegetables are subjected to a variety of abiotic stresses during production, handling, storage, and distribution. Some of these stresses may be very intense, which would lead to quality reductions (Hodges et al., 2005). It is crucial for understanding the types of abiotic stresses that impact fruits and vegetables, as well as their nature. Fruits and vegetables are facing abiotic stresses (e.g. drought, extreme temperatures, light and salinity) which affect plant's susceptibility to postharvest quality and shelf life. Abiotic stress induces metabolic changes associated with ripening, storage and nutritional status (Sommano et al.). Low temperature stress results in the production of, superoxide anions, hydrogen peroxide and lipid peroxidation products as well as to reductions of flavor volatile compounds in sensitive fruits and vegetables (Khaliq, 2015). The metabolism of ethylene is impacted by chilling stress and hastening the softening process. Additionally, it alters the metabolism of cell walls, which causes the upregulation of enzymes that break down cell walls, like endopolygalacturonase and pectin methylesterase enzymes.
Elicitors are crucial in triggering the defences responses against abiotic stressors. It is well known that when fruits and vegetables are exposed to elicitors, exhibited adaptive mechanisms. Fresh produce kept at low temperature was protected from abiotic stressors by exogenous application of γ-aminobutyric acid (Ali et al., 2022). Similarly, hydrogen peroxide (Duarte-Sierra et al.) and nitric oxide (Khaliq et al., 2021) delayed ripening and enhanced resistance of broccoli and custard apple fruits, respectively. Elicitors play a role in a number of defensive processes, including the regulation of enzyme activity, cellular defence against oxidative damage, and abiotic stress tolerance. Elicitors have a role in a number of defence mechanisms, including the activation of chitinase or β-1,3-glucanase enzyme activities, the production of proteins related to resistance, and the stimulation of the enzymes needed to produce phytoalexins and lignin. Plants can adapt to stress conditions when exogenous elicitors have applied. This collection covers the exogenous pre-harvest and post-harvest uses of elicitors to initiate defence responses against various stresses.
In summary, the articles in this research topic identified different abiotic stresses factors and evaluated the effect of elicitors for improving tolerance against abiotic stresses. This research topic also highlighted the importance of fruit quality maintenance, shelf life extension and overall to meet consumers' satisfaction. The application of elicitors might be a simple and effective technique for maintaining the postharvest quality of fresh produce.