Physiological and Enzymatic Antioxidant Responses of Solanum tuberosum Leaves to Arbuscular Mycorrhizal Fungal Inoculation under Water Stress.

Solanum tuberosum is one of the most widely cropped plant species worldwide; unfortunately, drought is one of the major constraints on potato productivity because it affects the physiology, biochemical processes, and yield. The use of arbuscular mycorrhizal fungi (AMF) has exhibited beneficial effects on plants during drought. The objective of this study was to analyse the effect of AMF inoculation on two genotypes of potato plants exposed to water stress, and the photosynthetic traits, enzymatic antioxidant activity, and exudation of low-molecular-weight organic acids (LMWOAs) of potato plants inoculated with two strains of AMF, Claroideoglomus claroideum (CC) and Claroideoglomus lamellosum (HMC26), were evaluated. Stomatal conductance exhibited a similar trend in the CC and HMC26 treatments for both potato genotypes; moreover, the photosynthetic rate significantly increased by 577.9% between the 100% soil humidity (S0) and 40% soil humidity (S2) stress levels for the VR808 genotype under the CC treatment. The activities of the enzymes catalase (CAT) and ascorbate peroxidase (APX) showed similar trends. In this study, there were different responses among genotypes and treatments. Inoculation with CC under S2 stress levels is a promising potential approach for improving potato growth under drought conditions.

Antioxidant Response, Phenolic Compounds and Yield of Solanum tuberosum Tubers Inoculated with Arbuscular Mycorrhizal Fungi and Growing under Water Stress.

Solanum tuberosum (potato) is one of the most common crops worldwide; however, it is sensitive to water stress, which necessitates the identification of alternative tools to improve their production. Here, we evaluated the inoculation of two arbuscular mycorrhizal fungi (AMF) strains, Claroideoglomus claroideum (CC), Claroideoglomus lamellosum (HMC26), and the MIX (CC + HMC26) in yield and phenolic and antioxidant response using chromatographic and spectroscopic methods in potato crops, at increasing levels of water stress, namely, with 100% (0), 70% (S1), and 40% (S2) soil humidity. Two caffeoylquinic acid isomers were detected and their levels showed a tendency to increase under stress together with the AMF inoculation, reaching up to 19.2 mg kg-1 of 5-caffeoylquinic acid and 7.4 mg kg-1 of caffeoylquinic acid isomer when CC was inoculated, and potato plants grew at the highest water starvation condition (S2). Regarding antioxidant activities, a differentiated response was detected depending on the AMF strain, highlighting the effect of HMC26 on Trolox equivalent antioxidant capacity (TEAC) method and CC in cupric reducing antioxidant capacity (CUPRAC) method, reaching up to 1.5 µmol g-1 of TEAC in plants inoculated with HMC26 and 0.9 µmol g-1 of CUPRAC in plants inoculated with CC, both in potato tubers of plants growing under the S2 stress condition. Meanwhile, the use of AMF did not influence the number and biomass of the tubers, but significant changes in the biochemical properties of tubers were observed. The results suggest that specific AMF adaptations to water stress must be considered when inoculation procedures are planned to improve the yield and quality of tubers in potato crops.

Stability of Phenolic Compounds, Antioxidant Activity and Color Parameters in Colored-Flesh Potato Chips.

Potato (Solanum tuberosum) chips are the most consumed snacks worldwide today. Colored potato chips prepared from potato cultivars with red and purple flesh are a novel alternative to traditional potato chips because of their higher phenolic compound content, such as anthocyanins and hydroxycinnamic acid derivatives (HCADs), which might make these chips healthier compared with traditional chips. There is little information on the stability of these compounds. In this study, the nutritional value of these chips was evaluated by determining phenolic profiles, antioxidant activity and color parameters with liquid chromatography diode array and mass spectrometry detection (HPLC-DAD-ESI-MS/MS) and spectrophotometric methods during storage for four months. Five anthocyanins and three HCADs were detected, with the latter compounds being the most abundant, with concentrations on average between the first (97.82 mg kg-1) and the last (31.44 mg kg-1) week of storage. Similar trends were observed in antioxidant activity and stability, with the CUPRAC method showing the highest response among all the methods employed. The color indices were stable throughout the storage time. Based on these results, colored-flesh potato chips are an optimal alternative for consumption because of their high retention of phenolic compounds and antioxidant activity during storage, providing potential benefits to human health.

Evaluation of the Antifungal Potential of Grape Cane and Flesh-Coloured Potato Extracts against Rhizoctonia sp. in Solanum tuberosum Crops.

Potato (Solanum tuberosum) is one of the most important food crops worldwide, and Rhizoctonia solani infection is one of the most common diseases. The objective of this study was to evaluate the antifungal activity of Vitis vinifera byproducts (VIDES) and flesh-coloured potato (FCP) extracts against Rhizoctonia sp. in potato crops. Photosynthetic traits, phenolic profiles, and antioxidant and enzymatic activities were determined. The VIDES extract showed a 151.4% improvement in stomatal conductance and a 258.5% improvement in the photosynthetic rate compared to the plants without infection. Regarding the enzymatic antioxidant activity, the best response was found in the FCP treatments with 30 min of application, with increases of 25%, 161%, and 450% in ascorbate peroxidase, catalase (CAT), and glutathione reductase (GR) activities, respectively, compared to plants without infection. For the VIDES extract, a 15 min application produced an 83% increase in CAT activity, whereas a 181% increase in GR activity compared to plants without infection was produced after a 30 min application. A similar behaviour was observed for antioxidant compounds, where FCP had a higher concentration of compounds and antioxidant activity. This finding suggests that FCP and VIDES promote the synthesis of plant-defence compounds against Rhizoctonia sp. in potato crops, in which the application time is a determining factor.

Physiological and Metabolic Effects of the Inoculation of Arbuscular Mycorrhizal Fungi in Solanum tuberosum Crops under Water Stress.

Solanum tuberosum is one of the most important crops in the world; however, drought has caused significant losses in its production. One solution is the use of arbuscular mycorrhizal fungi (AMF). In this study, the phenolic profiles and antioxidant activity of the leaves of two potato genotypes (VR808 and CB2011-104) were evaluated over time in crops inoculated with two strains of AMF, as well as a consortium, in combination with a commercial fungicide. In addition, three usable humidity levels were established after the beginning of tuberization. The phenolic compounds found during the first sampling time in the VR808 genotype reached a maximum of 3348 mg kg-1, and in the CB2011-104 genotype, they reached a maximum of 2982 mg kg-1. Seven phenolic compounds were detected in the VR808 genotype, and eleven were detected in the CB2011-104 genotype, reaching the highest concentration at the last sampling time. The antioxidant activity in the first sampling was greater than the Trolox equivalent antioxidant capacity (TEAC), and in the third sampling, the cupric reducing antioxidant capacity (CUPRAC) predominated. The association of AMF with the plant by PCA demonstrated that these fungi assist in protecting the plants against water stress, since in the last harvest, the results were favorable with both mycorrhizae.

Effect of Inoculation with Arbuscular Mycorrhizal Fungi and Fungicide Application on the Secondary Metabolism of Solanum tuberosum Leaves.

In potato (Solanum tuberosum) crops, the use of fungicides to control some diseases is widespread; however, it has been reported that this practice can modify the potato polyphenolic content, and new strategies oriented to the potato defense system are necessary. One alternative is the use of arbuscular mycorrhizal fungi (AMF) to improve the defense mechanisms of plants. In this study, phenolic profiles and antioxidant activities in leaves of three potato genotypes (CB2011-509, CB2011-104, and VR808) were evaluated in crops inoculated with three AMF strains (Claroideoglomus claroideum, Claroideoglomus lamellosum, and Fumneliformis mosseae) and with AMF in combination with the use of two commercial fungicides (MONCUT [M] and ReflectXtra [R]). Eight phenolic compounds were detected, mainly hydroxycinnamic acids (HCAD) and flavonols, in samples where the highest concentrations of HCAD were obtained, 5-caffeoylquinic acid was the most abundant phenolic. The antioxidant activity was higher using the cupric reducing antioxidant capacity (CUPRAC) and ferric reducing antioxidant power (FRAP) methods. The association of AMF with plants had benefits on the secondary metabolism; however, the response differed according to genotype. The different combinations of potato genotypes, AMF strain, and fungicide modified the content of phenolic compounds in leaves in different ways; the treatment using C. lamellosum and ReflectXtra was the ideal combination for the genotypes analyzed here, with the higher antioxidant response, which supports the further technological evaluation of efficient AMF strains and fungicides in potato crops.

Metabolic and antioxidant effects of inoculation with arbuscular mycorrhizal fungi in crops of flesh-coloured Solanum tuberosum treated with fungicides.

BACKGROUND: Solanum tuberosum tubers have higher content of phenolic compounds such as hydroxycinnamic acid derivatives (HCAD) and anthocyanins in coloured genotypes. The use of fungicides for crops is common, but there are few studies regarding the interaction of fungicides and arbuscular mycorrhizal fungi (AMF). Here, the AMF-plant interactions and the metabolic responses of three potato genotypes with different tuber colorations (VR808, CB2011-509 and CB2011-104) inoculated with Claroideoglomus claroideum (CC), Claroideoglomus lamellosum (HMC26) or Funneliformis mosseae (HMC7) were studied together with the use of the fungicides MONCUT (M) and ReflectXtra (R). Mycorrhizal traits, phenolic compound profiles and antioxidant activity (AA) were evaluated. RESULTS: Despite only two HCADs being identified, with 5-caffeolquinic acid the most abundant, four anthocyanins were detected only in purple potato genotypes. The anthocyanin and HCAD profiles, as well as AA, showed that the CB2011-104 genotype had better characteristics than the other genotypes, while VR808 and CB509 showed similar responses. The responses were dependent on the specific combinations of genotype, fungicide and the AMF strain, and generally showed better responses when colonized by AMFs. CONCLUSION: The three potato genotypes had differential responses depending on the inoculated AMFs and the fungicide applied before sowing, where the optimal combinations for antioxidant response, mycorrhization degree and performance were HMC26/R for VR808, HMC7/M for CB2011-509 and HMC26/M for CB2011-104. Our results suggest the existence of functional compatibility that can be registered as beneficial effects even at the genotypic level of the host regarding a specific AMF strain. © 2021 Society of Chemical Industry.

Noticeable Quantities of Functional Compounds and Antioxidant Activities Remain after Cooking of Colored Fleshed Potatoes Native from Southern Chile.

The effect of cooking on the concentrations of phenolic compounds and antioxidant activities in 33 colored-fleshed potatoes genotypes was evaluated. The phenolic profiles, concentrations, and antioxidant activity were evaluated with a liquid chromatography diode array detector coupled to a mass spectrometer with an electrospray ionization interface (HPLC-DAD-ESI-MS/MS). Eleven anthocyanins were detected; in the case of red-fleshed genotypes, these were mainly acyl-glycosides derivatives of pelargonidin, whereas, in purple-fleshed genotypes, acyl-glycosides derivatives of petunidin were the most important. In the case of the purple-fleshed genotypes, the most important compound was petunidin-3-coumaroylrutinoside-5-glucoside. Concentrations of total anthocyanins varied between 1.21 g kg-1 in fresh and 1.05 g kg-1 in cooked potato and the decreases due to cooking ranged between 3% and 59%. The genotypes that showed the highest levels of total phenols also presented the highest levels of antioxidant activity. These results are of relevance because they suggest anthocyanins are important contributors to the antioxidant activity of these potato genotypes, which is significant even after the drastic process of cooking.

Effect of the frying process on the composition of hydroxycinnamic acid derivatives and antioxidant activity in flesh colored potatoes.

Phenolic composition of potatoes (Solanum tuberosum) with colored flesh has been previously reported, highlighting their anthocyanin composition. However, there is less information available about the profiles and concentrations of hydroxycinnamic acid derivatives (HCADs) in these potatoes. In pigmented potatoes from Southern Chile, three HCADs have been detected, corresponding to the trans isomers of 3-, 4- and 5-caffeoylquinic acid. It is remarkable that after frying, the HCAD concentrations increased 493% compared to those of fresh potatoes. The same tendency has been observed for total phenols and antioxidant activity of the chips. The results obtained are relevant in relation to the classification of pigmented potatoes as functional foods not only due to their anthocyanin content but also due to their higher content of HCADs, especially since their concentration increases considerably after frying, thus contributing to their antioxidant activity and potential beneficial effects for human health compared with uncolored genotypes.