Plant Secondary Metabolism as a Response to Single or Multiple Stresses

A special issue of Agriculture (ISSN 2077-0472). This special issue belongs to the section "Crop Production".

Deadline for manuscript submissions: closed (15 January 2023) | Viewed by 26721

Special Issue Editors


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Guest Editor
Department of Agricultural Sciences, University of Naples Federico II, 80055 Portici, Italy
Interests: vegetable quality; sustainable agriculture; horticultural crops; hydroponics and soilless culture; biofortification; microgreens; functional foods; microbial and non-microbial biostimulants; carbon sequestration; nutrient cycling
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Department of Agricultural Sciences, University of Naples Federico II, 80055 Portici, Italy
Interests: horticultural crops; microgreens; protected cultivation; hydroponics; plant biostimulants; nutrient eustress; biofortification; space farming; nutrient recovery from urine
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Secondary metabolites (e.g., flavonoids, anthocyanins, polyphenols) are an innate defense against stress, as all plants can synthesize them. In some species, stress response is enhanced by previous mild or short-term stresses, during which the plant channels its energy towards the synthesis of secondary molecules, to the detriment of growth or other metabolic activities. The type or quantity of secondary metabolites in plants can vary according to pre-harvest factors and plant phenological stage (e.g., microgreens, baby leaf, adult stage). In a scenario of rapid and intense climate change, the activation of the secondary metabolism must be just as rapid and intense to allow the plant to survive. Furthermore, plants are subjected not only to single biotic or abiotic stresses, but also to multiple stresses. Genetic variability cannot quickly create plant organisms capable of surviving such stresses. The choice of eco-sustainable agricultural practices that can both reduce the impact on natural resources (e.g., soil, air, water) and increase the plant defense response is a valuable solution for modern agriculture. On the other hand, at present, consumers’ interest is directed towards functional foods which are rich in secondary metabolites. This Special Issue aims to understand the agronomic, metabolic, and physiological factors which contribute to activate the secondary metabolism in response to single or multiple abiotic and/or biotic stresses.

Dr. Maria Giordano
Dr. Christophe El-Nakhel
Guest Editors

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Keywords

  • secondary metabolites
  • climate change
  • single/multiple stresses
  • biotic/abiotic stresses
  • eco-sustainable agricultural practices
  • functional foods
 

Published Papers (8 papers)

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Research

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26 pages, 4092 KiB  
Article
The Impact of Salinity on Growth, Physio-Biochemical Characteristics, and Quality of Urospermum picroides and Reichardia picroides Plants in Varied Cultivation Regimes
by Nikolina Vidalis, Maria Kourkouvela, Dimitrios-Christos Argyris, Georgios Liakopoulos, Alexios Alexopoulos, Spyridon A. Petropoulos and Ioannis Karapanos
Agriculture 2023, 13(9), 1852; https://doi.org/10.3390/agriculture13091852 - 21 Sep 2023
Viewed by 951
Abstract
Salinity stress is severely affecting modern horticulture and puts food security under threat for current and future generations. The aim of the present study was to evaluate the effect of saline conditions (three salinity levels: 2.0, 5.0 and 10.0 dS m−1) [...] Read more.
Salinity stress is severely affecting modern horticulture and puts food security under threat for current and future generations. The aim of the present study was to evaluate the effect of saline conditions (three salinity levels: 2.0, 5.0 and 10.0 dS m−1) on the growth, physiological processes and quality of two wild edible species (Urospermum picroides and Reichardia picroides) grown under three different cropping systems (pots indoors (GP) and outdoors (FP); and floating hydroponics (FH)). Our results indicate that high salinity affected growth parameters in all the studied cropping systems in the case of U. picroides, whereas R. picroides was not affected only when grown in pots outdoors. Moreover, total soluble solids content and titratable acidity in both species were not affected by high salinity for any of the cropping systems, except for in the case of FP system. Similarly, carotenoids content decreased under high salinity when both species were grown in the FP system. A varied effect was recorded for total phenolic compounds content in response to salinity levels, although the FP system resulted in considerably higher phenolics accumulation in both species, while proline content increased when plants were subjected to high salinity, regardless of the cropping system. The antioxidant activity also varied among the studied treatments for both assays (TEAC and FRAP), although cultivation outdoors in pots resulted in considerably higher values compared to the other systems. Finally, nitrate content showed decreasing trends with increasing salinity in plants grown in the GP (both species) and FP system (only U. picroides), whereas no significant differences in physiological parameters in comparison to the control treatment were recorded, except for the stomatal conductance (FP and GP system) and transpiration rate (FP) of R. picroides plants. In conclusion, it seems that the tested plant species responded differently to the salinity treatments but they both displayed a lack of severe stress even at high salinity. Full article
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22 pages, 4136 KiB  
Article
Agronomic, Physiological, Genetic and Phytochemical Characteristics of Onion Varieties Influenced by Daylength Requirements
by Zahra Kiani, Kambiz Mashayekhi, Nadezhda Golubkina, Seyyed Javad Mousavizadeh, Khalil Zaynali Nezhad and Gianluca Caruso
Agriculture 2023, 13(3), 697; https://doi.org/10.3390/agriculture13030697 - 17 Mar 2023
Cited by 3 | Viewed by 2037
Abstract
The evaluation of A. cepa biodiversity provides onion breeders with great prospects to obtain plants with high resistance to environmental factors, remarkable yield, and product quality. Genetic diversity assessment of a collection of nine short- and long-day onion landraces and varieties originated from [...] Read more.
The evaluation of A. cepa biodiversity provides onion breeders with great prospects to obtain plants with high resistance to environmental factors, remarkable yield, and product quality. Genetic diversity assessment of a collection of nine short- and long-day onion landraces and varieties originated from different Iranian regions, using ISSR markers and UPGMA dendrograms, was carried out for the first time. Short-day landraces (Sarze, Sarkoreh, and Kerman) originated from low latitude and short-day hybrids (Mirela and Soberana) demonstrated high genetic similarity, in terms of physiological responses to day length and temperature during the crop cycle and bulbing stage initiation. Contrarily, high latitude landraces (Azarshahr, White Gorgan, Kurdistan, and Esfahan) showed low biometrical, agronomic and genetic similarity with commercial short-day onions. Specific differences in morphological reactions between these two groups displayed diverse responses of plants to day length and temperature. Long- and short-day cultivars displayed significant differences in the dynamics of leaf and scale number, leaf and root length, dry and fresh weight, and bulbing ratio and bulb diameter, which were in accordance with ISSR data. The local landraces Azarshahr, Kurdistan, and Esfahan had high antioxidant status, suggesting high prospects for their utilization as an alternative to foreign F1 hybrid varieties. Full article
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14 pages, 1992 KiB  
Article
Effects of Melatonin Dose on Fruit Yield, Quality, and Antioxidants of Strawberry Cultivars Grown in Different Crop Systems
by Volkan Okatan, Mehmet Atilla Aşkın, Mehmet Polat, Ibrahim Bulduk, Ayşen Melda Çolak, Sultan Filiz Güçlü, İbrahim Kahramanoğlu, Alessio Vincenzo Tallarita and Gianluca Caruso
Agriculture 2023, 13(1), 71; https://doi.org/10.3390/agriculture13010071 - 26 Dec 2022
Cited by 4 | Viewed by 1672
Abstract
Melatonin acts as a seed germination activator, plant growth regulator, leaf senescence retardant, and, in general, has a multifunctional role as a ‘defence molecule’; furthermore, by interacting with other molecules, such as phytohormones and gaseous molecules, it greatly enhances plant adaptation to different [...] Read more.
Melatonin acts as a seed germination activator, plant growth regulator, leaf senescence retardant, and, in general, has a multifunctional role as a ‘defence molecule’; furthermore, by interacting with other molecules, such as phytohormones and gaseous molecules, it greatly enhances plant adaptation to different environments. However, there are not enough studies about the use of melatonin on horticultural crops, and even fewer studies have outlined the differences related to this phytohormone use between protected environment and in open field. The two latter systems have different growing conditions that could lead to diversified application doses. As the choice of melatonin dose depends on all crop system components, the present research aimed to assess the effects of three melatonin concentrations (1 ppm, 5 ppm and 10 ppm) plus an untreated control, on yield, quality, and antioxidants of four strawberry cultivars (i.e., Kabarla, Fortuna, Sweet Ann, Festival) grown either in greenhouse or in open field. Research was conducted to assess the yield parameters were better affected by greenhouse than open field, and mean fruit weight was the highest in cultivar Sweet Ann. In open field 10 ppm showed the highest values of fruit number and yield, but in greenhouse did not differ from 5 ppm which led to the highest fruit number. At all melatonin doses, cultivar Kabarla demonstrated the highest yield, compared to the other cultivars, with the maximum value of about 46 t·ha−1. Plant dry weight was 90% higher under greenhouse than in open field conditions, and 52% or 132% higher with cultivar Kabarla in comparison with Fortuna and Sweet Ann, respectively. The melatonin dose of 10 p.p.m showed 56% higher plant dry weight in comparison to the untreated control. Fortuna showed higher values of fruit dry matter, soluble solids, and glucose than Sweet Ann. The fruit dry matter was 7% lower at 10 ppm melatonin than in the untreated control. Fructose was higher under 1 ppm melatonin with 245 mg·g−1 d.w. compared to the untreated control with 220 mg·g−1 d.w. in Festival, whereas in Fortuna was the highest in the control fruits, the latter also showing the highest titratable acidity in Fortuna and Sweet Ann. The highest phenolics content was recorded under 10 ppm melatonin in open field, and with 5 ppm in greenhouse; the phenolics content was the highest under 1 ppm melatonin dose in Kabarla and 5 ppm in Fortuna. Under the protected environment 5 and 10 p.p.m. melatonin elicited the highest accumulation of ascorbic acid; 10 ppm were more effective in Fortuna and Sweet Ann, and 5 ppm in Festival. The most enhanced antioxidant activity was recorded under 5 p.p.m. melatonin dose in Fortuna and Festival. The present study confirms that the dose of melatonin to apply to strawberry crop closely relates both to cultivar and crop system. Full article
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21 pages, 4064 KiB  
Article
Comparison Study on Wild and Cultivated Opuntia sp.: Chemical, Taxonomic, and Antioxidant Evaluations
by Fares Boudjouan, Walid Zeghbib, João Carneiro, Raquel Silva, João Morais, Vitor Vasconcelos and Graciliana Lopes
Agriculture 2022, 12(11), 1755; https://doi.org/10.3390/agriculture12111755 - 24 Oct 2022
Cited by 3 | Viewed by 2089
Abstract
Opuntia species are well-known for their use in folk medicine and richness in many bioactive compounds. This study aims to realize a taxonomic study and to evaluate the polyphenols content and antioxidant potential of edible parts of cultivated and wild Opuntia sp. fruits, [...] Read more.
Opuntia species are well-known for their use in folk medicine and richness in many bioactive compounds. This study aims to realize a taxonomic study and to evaluate the polyphenols content and antioxidant potential of edible parts of cultivated and wild Opuntia sp. fruits, using different in-vitro bioassays. The phylogenetic analysis confirmed the assignment of the samples to Opuntia genera. The Opuntia fruit fractions (seeds, pulp, and entire fruit) exhibited different amounts of polyphenols, with the highest values recorded for the wild species, and particularly their pulp (1140.86 mg GAE/100 g DM, and 155.62 QE/100 g DM for total phenolic and flavonoid compounds, respectively). Among the antioxidant activities, wild pulp exhibited the greatest antioxidant potential with a high radical scavenging activity (72.34% and 92.12% for hydrogen peroxide and hydroxyl radicals, respectively). The best nitric oxide scavenging activity was found for cultivated fruit fraction, with 55.22%. The statistical analysis also confirmed a significant correlation between the antioxidant activities and the phenolic compounds and flavonoids (>0.90, p ≤ 0.001) in all Opuntia extracts. Finally, both Opuntia fruits demonstrated a good antioxidant potential, enhancing the interest of this species as a non-pharmacological approach in a wide variety of disorders and diseases associated with oxidative stress, and paving the way to Opuntia sp. economic valorization. Full article
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15 pages, 1218 KiB  
Article
A Field Screening of a Pomegranate (Punica granatum) Ex-Situ Germplasm Collection for Resistance against the False Spider Mite (Tenuipalpus punicae)
by Sharavan Manbhar Haldhar, Ramesh Kumar, Giandomenico Corrado, Mukesh Kumar Berwal, Jagan Singh Gora, Narit Thaochan, Dilip Kumar Samadia, Tajamul Hussain, Youssef Rouphael, Pradeep Kumar and Boris Basile
Agriculture 2022, 12(10), 1686; https://doi.org/10.3390/agriculture12101686 - 13 Oct 2022
Cited by 9 | Viewed by 1743
Abstract
Mite management is a major problem in pomegranate (Punica granatum L.) cultivation in the arid and semi-arid regions of India and other Asian countries. The aim of this work was to investigate the susceptibility to the false spider mite (Tenuipalpus punicae [...] Read more.
Mite management is a major problem in pomegranate (Punica granatum L.) cultivation in the arid and semi-arid regions of India and other Asian countries. The aim of this work was to investigate the susceptibility to the false spider mite (Tenuipalpus punicae) in a germplasm collection of Indian pomegranates. A field screening of 73 accessions allowed to define different classes of susceptibility (from very low to very high) based on the percentage of infested leaves. Twenty-two accessions, representative of the empirically identified five susceptibility classes, were further tested. The field screening against the mite, extended to another two years, showed that the infestation level did not display a significant interaction with the growing season, and highly correlated between the different growing seasons. The analysis of the tree vegetative growth (height, canopy size, and stem diameter), main phytochemical classes (total phenolics, flavonoids, and tannins) and the antioxidant activity of the leaves indicated strong significant negative correlations between the infestation level and the biochemical traits. Multidimensional reduction of the measured traits revealed that the extreme classes of susceptibility to mites are mainly separated according to the accumulation of phytochemicals in leaves. This work, for the first time, allowed the identification of pomegranate germplasm with low susceptibility to T. punicae, with positive and useful implications for the establishment of new orchards, plant breeding, and the identification of allelochemicals of the leaves directly affecting mites. Full article
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18 pages, 1590 KiB  
Article
Biostimulants Improve Plant Growth and Bioactive Compounds of Young Olive Trees under Abiotic Stress Conditions
by Giulia Graziani, Aurora Cirillo, Paola Giannini, Stefano Conti, Christophe El-Nakhel, Youssef Rouphael, Alberto Ritieni and Claudio Di Vaio
Agriculture 2022, 12(2), 227; https://doi.org/10.3390/agriculture12020227 - 04 Feb 2022
Cited by 14 | Viewed by 2944
Abstract
The negative impacts of extreme heat and drought on olive plants have driven the quest for mitigation approaches based on the use of biostimulants, which have proved to be effective in contrasting environmental stresses. The aim of our study was to evaluate the [...] Read more.
The negative impacts of extreme heat and drought on olive plants have driven the quest for mitigation approaches based on the use of biostimulants, which have proved to be effective in contrasting environmental stresses. The aim of our study was to evaluate the effectiveness of six biostimulants in mitigating high temperature and water stress in young olive trees in terms of vegetative and eco-physiological parameters as well as bioactive compound content. Biostimulants based on glycine betaine and macro- and micro-algae effectively protected the plants from abiotic stress by improving their eco-physiological and vegetative parameters. At the end of the growing season, olive plants were experiencing water deficit which had built up through the summer months. At this time, the glycine betaine-treated plants had a three-fold higher stomatal conductance compared with the control, while plants sprayed with the seaweed mix had a relative water content 33% higher than the control. The kaolin treatment resulted in higher total phenolics and antioxidant activities (DPPH, FRAP and ABTS) in water stress conditions and caused an increase of 238.53 and 443.49% in leaves total polyphenols content in 100% and 50% water regime, respectively. This study showed the effectiveness of biostimulants in mitigating the damage from abiotic stress on young olive trees, by improving some vegetative, eco-physiological and leaf nutraceutical parameters. Further studies are needed to test the efficiency of these biostimulants in open field conditions on olive trees in full production. Full article
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11 pages, 1870 KiB  
Article
Pigment Production under Cold Stress in the Green Microalga Chlamydomonas reinhardtii
by Supakorn Potijun, Chonlada Yaisamlee and Anchalee Sirikhachornkit
Agriculture 2021, 11(6), 564; https://doi.org/10.3390/agriculture11060564 - 20 Jun 2021
Cited by 13 | Viewed by 3614
Abstract
Microalgae have long been used for the commercial production of natural colorants such as carotenoids and chlorophyll. Due to the rising demand for carotenoids and other natural products from microalgae, strategies to increase production efficiency are urgently needed. The production of microalgal biorefineries [...] Read more.
Microalgae have long been used for the commercial production of natural colorants such as carotenoids and chlorophyll. Due to the rising demand for carotenoids and other natural products from microalgae, strategies to increase production efficiency are urgently needed. The production of microalgal biorefineries has been limited to countries with moderate climates. For countries with cooler climates and less daylight, methodologies for the efficient production of microalgal biorefineries need to be investigated. Algal strains that can be safely consumed as whole cells are also attractive alternatives for developing as carotenoid supplements, which can also contain other compounds with health benefits. Using such strains helps to eliminate the need for hazardous solvents for extraction and several other complicated steps. In this study, the mesophilic green alga Chlamydomonas reinhardtii was employed to study the effects of cold stress on cell physiology and the production of pigments and storage compounds. The results showed that temperatures between 10 and 20 °C induced carotenoid and chlorophyll accumulation in the wild-type strain of C. reinhardtii. Interestingly, the increased level of carotenoids suggested that they might play a crucial role in cold stress acclimation. A temperature of 15 °C resulted in the highest carotenoid and chlorophyll productivity. At this temperature, carotenoid and chlorophyll productivity was 2 times and 1.3 times higher than at 25 °C, respectively. Subjecting a mutant defective in lutein and zeaxanthin accumulation to cold stress revealed that these two carotenoids are not essential for cold stress survival. Therefore, cold temperature could be used as a strategy to induce and increase the productivity of pigments in C. reinhardtii. Full article
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Review

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30 pages, 355 KiB  
Review
Response and Defence Mechanisms of Vegetable Crops against Drought, Heat and Salinity Stress
by Maria Giordano, Spyridon A. Petropoulos and Youssef Rouphael
Agriculture 2021, 11(5), 463; https://doi.org/10.3390/agriculture11050463 - 19 May 2021
Cited by 106 | Viewed by 9554
Abstract
Environmental pollution, increasing CO2 atmospheric levels and the greenhouse effect are closely associated with the ongoing climate change and the extreme climatic events we are witnessing all over the Earth. Drought, high temperature and salinity are among the main environmental stresses that [...] Read more.
Environmental pollution, increasing CO2 atmospheric levels and the greenhouse effect are closely associated with the ongoing climate change and the extreme climatic events we are witnessing all over the Earth. Drought, high temperature and salinity are among the main environmental stresses that negatively affect the yield of numerous crops, challenging the world food safety. These effects are more profound in vegetable crops which are generally more susceptible to climate change than field or tree crops. The response to single or combined environmental stressors involves various changes in plant morphology and physiology or in molecular processes. Knowing the mechanisms behind these responses may help towards the creation of more tolerant genotypes in the long-term. However, the imediacy of the problem requires urgently short-term measures such as the use of eco-sustainable agricultural practices which can alleviate the negative effects of environmental pollution and allow vegetable crops to adapt to adverse climatic conditions. In this review, the main abiotic stressors were examined, namely drought, heat and salinity stress, focusing on the mechanisms involved in the most common vegetable crops responses. Moreover, the use of eco-sustainable cultural techniques, such as biostimulants, grafting and genomic sequencing techniques, to increase the quality of tomato crop under adverse environmental conditions are also presented. Full article
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