This study provides information that allows for improvements in strawberry fruit quality by agronomic management, with a potential beneficial effect on the health of consumers. © 2018 Society of Chemical Industry.

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.

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.

BACKGROUND: Strawberries are consumed worldwide. In Chile, strawberry production has been established in Andisols, were phosphorus is scarce. Traditional fertilization (TF) and organic fertilization (OF) have both been established there. This study examined their impact on the polyphenolic content of strawberries. RESULTS: Two anthocyanins were identified by high performance liquid chromatography with diode array detection coupled to mass spectrometry (HPLC-DAD-ESI-MS/MS). The average total anthocyanin concentrations were found to be 651 mg kg −1 fresh weight in 100% OF, which represents a 56% increase compared to fruits that were not fertilized. In the case of flavonols, only quercetin-rhamnoside was identified, and its concentration reached 14.6 mg kg −1 with 100% OF. The ascorbic acid concentration reached 0.54 g kg −1 in 50% TF (a 20% increase over fruits without fertilization, WF). The antioxidant activities slightly increased in the fruits subjected to TF and OF in comparison with WF treatment. CONCLUSION: These results support a management strategy for obtaining the best quality and potential beneficial effects in health by increasing anthocyanins and other polyphenols under OF. ReagentsThe commercial standard of pelargonidin-3-glucoside chloride (98.95%) was obtained from Phytolab (Vestenbergsgreuth, Germany). Quercetin (> 95%) and ascorbic acid (99.7%) was acquired from Sigma-Aldrich (Steinheim, Germany). The standards of TROLOX (6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxilic acid), ABTS (2,2 ′ -azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)), gallic acid and sodium carbonate were obtained from Sigma-Aldrich. HPLC grade solvents as water, methanol, acetonitrile and p.a. grade as formic acid, ammoniac, and hydrochloric acid were acquired from Merck (Darmstandt, Germany). Identification and quantification of anthocyanins and flavonolsHigh performance liquid chromatography with diode array detection coupled to mass spectrometry (HPLC-DAD-ESI-MS/MS) analyses of anthocyanins were carried out using a Shimadzu HPLC system (Tokyo, Japan) equipped with a quaternary LC-20AT pump with a DGU-20A5R degassed unit, a CTO-20A oven, an SIL-20a autosampler, and a UV-vis diode array spectrophotometer (SPD-M20A). The compounds were identified by a HPLC-DAD system coupled to a mass spectrometer (QTrap LC/MS/MS 3200 Applied Biosystem MDS Sciex system (Foster City, CA, USA)). The instrument was controlled and data were collected using Analyst J Sci Food Agric 2019; 99: 2404-2410

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