Plant biofortification with selenium in interaction with the application of an arbuscular mycorrhizal fungi (AMF)-based formulate,with the goal of enhancing Se bioavailability, is beneficial for the development of the environmentally friendly production of functional food with a high content of this microelement. Research was carried out in order to assess the effects of an AMF-based formulate and a non-inoculated control in factorial combination with two selenium treatments with an organic (selenocystine) or inorganic form (sodium selenate) and a non-treated control on the yield, quality, antioxidant properties, and elemental composition of shallot (Allium cepa L. Aggregatum group). Selenocystine showed the best effect on the growth and yield of mycorrhized plants, whereas sodium selenate was the most effective on the non-inoculated plants. The soluble solids, total sugars, monosaccharides, titratable acidity, and proteins attained higher values upon AMF inoculation. Sodium selenate resulted in higher soluble solids, total sugars and monosaccharide content, and titratable acidity than the non-treated control, and it also resulted in higher monosaccharides when compared to selenocystine; the latter showed higher protein content than the control. Calcium, Na, S, and Cl bulb concentrations were higher in the plants inoculated with the beneficial microorganisms. Calcium and sodium concentrations were higher in the bulbs of plants treated with both the selenium forms than in the control. Selenocystine-treated plants showed enhanced accumulation of sulfur and chlorine compared to the untreated plants. The AMF inoculation increased the bulb selenium content by 530%, and the Se biofortification with selenocystine and sodium selenate increased this value by 36% and 21%, respectively, compared to control plants. The AMF-based formulate led to increases in ascorbic acid and antioxidant activity when compared to the non-inoculated control. The bulb ascorbic acid was increased by fortification with both selenium forms when compared to the non-treated control. The results of our investigation showed that both AMF and selenium application represent environmentally friendly strategies to enhance the overall yield and quality performances of shallot bulbs, as well as their selenium content.

Leek (Allium porrum) is known for its high antioxidant activity and the ability to accumulate significant amounts of potassium and iron. We assessed yield, quality indicators, antioxidants and elemental composition of nine leek cultivars grown in greenhouses under organic or conventional systems in the Moscow region. The management system did not affect yield, which attained the highest value with the cultivar Giraffe and the lowest with Premier and Cazimir. Pseudo-stem dry matter and sugars were higher with organic management, whereas nitrate concentration was higher with conventional management. The cultivars Vesta and Summer Breeze showed the highest dry matter and total sugar content, whereas Goliath had the highest antioxidant, selenium and potassium concentrations. Among the antioxidants, ascorbic acid attained higher values with organic management. The antioxidant system of leek was characterized by highly significant positive correlations between: Se and polyphenols, Se and ascorbic acid, Se and K, ascorbic acid and polyphenols, ascorbic acid and K, polyphenols and K (r = 0.94, 0.94, 0.95, 0.94, 0.95, 0.96, respectively, at P ≤ 0.001). Negative correlations were recorded between leaf and pseudo-stem Se and between leaf and pseudo-stem polyphenols (r = −0.922 and −0.976, respectively, at P ≤ 0.001). Among the mineral elements, only K was significantly affected by the management system, showing a higher content in organically grown pseudo-stems. Varietal differences in pseudo-stem element composition showed strong positive correlations of: Al with As, Co, Li, Pb and V; Cr with I, Mg, Si, Ca; V with As, Co and Fe; negative correlations of Se with Cr and I. Compared to related species such as garlic (A. sativum), leek accumulated levels equal to garlic of K, Mg, P, Cd, Cu, Mn, Se, Zn, lower levels of Si and significantly higher amounts of Ca, Na, Al, As, Cr, Ni, Pb, Sr, V, Sn, B, Co, Fe, I, Li. The strong relationships between quality, antioxidant and mineral components in leek plants may give wide possibilities in breeding programs for both conventional and organic management systems in greenhouses.

The fundamental direction of modern agriculture development is elaboration and utilization of technologies that ensure environmental safety, high plant productivity and quality of crop production. In this connection, the issues of optimization of mineral nutrition and water supply, immunity enhancement and protection of plants against various forms of biotic and abiotic stresses without significant environmental stress are of current interest. Normal growth and development of almost all plants on the Earth depends on the presence of mycorrhizal fungi in the soil, which ensure optimal plant nutrition and water supply due to the huge number of hyphae. The review discusses the prospects for the use of arbuscular mycorrhizal fungi in the cultivation of Allium species, as the most responsive plants to the effects of mycorrhizae due to the poorly developed root system that hinders the nutrition of plants. It is noted that utilization of arbuscular mycorrhizal fungi may provide the reduction of the amount of fertilizers, herbicides and insecticides needed for high productivity of crops. The review deals with the peculiarities of symbiotic interrelations of different species of mycorrhizal fungi (pure and mixed cultures, mainly of the genus Glomus) with different Allium species (onion, garlic, shallot, leek, A. roylei, A. fistulosum, A. galanthum). Questions of agricultural crops quality as affected by arbuscular mycorrhizal fungy are discussed. Data on the effect of climatic conditions on the efficiency of arbuscular mycorrhizal fungi utilization in Allium production are discussed. The possibility of increasing the efficiency of biofortification of Allium species with selenium via utilization of arbuscular-mycorrhizal fungi is noted, as well as an increase in the content of biologically active sulfur-containing compounds in garlic. Particular attention is paid to the necessity of the development of arbuscular mycorrhizal fungi preparations in Russia – the country not using this ecologically friendly technology at present.

Production of functional food with significant antioxidant and anti-carcinogen activity is considered to be extremely significant in conditions of global ecological crisis. Among Allium species, wild garlic (Allium ursinum L.) along with the ordinary garlic are known to be the leaders in accumulation of natural antioxidants and sulfur-containing compounds with strong anti-carcinogen activity. Taking into consideration that Allium species belong to a group of natural accumulators of selenium, foliar biofortification of wild garlic with sodium selenate was achieved in Gudermes region of the Chechen republic. It was demonstrated that fortification of plants with selenium resulted in significant increase of chlorophyll a and b as well as carotene content, and two-fold increase of both polyphenol concentration and total antioxidant activity. Total dose of 2 mg Na2Se04 per square meter provided 14.4-fold increase of selenium content in A. ursinum leaves. Biofortification of plants with selenium resulted in 1.36, 1.28 and 1.38-fold increase of Cr, Fe and V concentration in leaves compared to leaves of non fortified plants. Leaves of A. ursinum fortified with selenium showed anomalously low Si content compared to non fortified plants. Compared to A. ursinum grown in Moscow region, wild garlic of the Chechen republic accumulated 2-fold lower levels of dry matter and 4.8-fold higher levels of monosaccharides. Compared to non fortified garlic leaves, those of A. ursinum demonstrated significantly higher levels of Cu, Fe, Mg и Zn. The results obtained suggest that A. ursinum fortified with selenium may be considered as a new functional food with strong antioxidant activity.

Garlic (Allium sativum L.) is a widely consumed bulbous crop both worldwide and in Russia. About 200,000 tons of garlic is produced in Russia annually (https://rosstat.gov.ru/). Significant pre- and post-harvest losses of garlic regularly occur due to Fusarium sp. (Taylor et al., 2013). Since September 2018, rotting has been observed in Russia during garlic bulb storage (data of the Federal Scientific Vegetable Center, FSVC, Moscow Region). The outer bulb surface looked healthy, but underneath the integumentary scales, the cloves had light brown and brown spots. When grown, diseased plants were characterized by root and bulb disruption and leaf drying; for some cultivars, up to 100% of plants died. In January 2020, cv. Strelets and Dubkovsky bulbs, collected in July 2019, with rot symptoms, were taken from the FSVC storage. Necrotic clove tissue fragments (0.2-0.5 cm) were cut, sanitized with 70% ethanol for 3 min, rinsed with sterile water, and incubated on potato dextrose agar (PDA) with 1 mg/ml ampicillin at 22°C in the dark. Four single-spore cultures were obtained from four diseased bulbs. After 6 days of incubation, the isolates produced abundant aerial white mycelia and acquired a purple pigmentation. The hyphae were hyaline with septation. All isolates (Dubkovsky, Dubkovsky 2, Strelets, and Strelets 2) produced numerous oval unicellular microconidia without septa, 4.1 to 11.6 × 1.3 to 3.4 µm (n = 50) and very few macroconidia with 3-4 septa (21 to 26 × 3 to 4 µm (n = 30)), narrowed at both ends. The cultural and conidial characteristics of the isolates corresponded to Fusarium species (Leslie and Summerell 2006). To determine the species, DNA was extracted from four isolates, and the internal transcribed spacer (ITS), and genes of translation elongation factor 1α (EF1α) and subunits 1 and 2 of DNA-directed RNA polymerase II (RPB1 and RPB2) were amplified and sequenced with primers ITS1/ITS4 (White et al. 1990), EF1/EF2 (O'Donnell et al. 1998a), RPB1-F5/RPB1-R8 (O’Donnell et al. 2010) and fRPB2-5F/fRPB2-7cR (Liu et al. 1999). The obtained sequences were identical for all four isolates. The isolate Strelets sequences were deposited in NCBI GenBank (MW149129 (ITS), MW161161 (EF1α), MW413302 (RPB1) and MW413303 (RPB2)); their analysis in MLST (http://fusarium.mycobank.org) showed 98.8-99.8% similarity to F. proliferatum (NRRL 13582, 13598 and others), which is part of the F. fujikuroi complex (O'Donnell et al. 1998b). The test on pathogenicity was performed two times according to (Leyronas et al. 2018). For this, three replicates of 10 cloves (cv. Strelets) were soaked in a conidial suspension (~106 conidia/ml; Strelets isolate) for 24 h. Ten control cloves were soaked in sterile water. The cloves were incubated on Petri dishes (5 cloves on a dish; on filter paper wettened with sterile water) in the dark at 23°C. After 5 days, brown lesions and white mycelium developed on the surface of the treated cloves. The taxonomic status of the fungus isolated from necrotic tissue was determined as F. proliferatum according to the ITS, EF1α, RPB1 and RPB2 analysis. Garlic basal and bulb rot is known to be caused by F. oxysporum f. sp. cepae and F. proliferatum (Snowdon 1990). This study is the first report of F. proliferatum causing rot of garlic bulbs during storage in Russia. F. proliferatum produces a variety of mycotoxins during bulb infestation, and our findings are important for diagnosing a Fusarium disease and the use of garlic crop in culinary and medicine. Funding The reported study was funded by Russian Foundation for Basic Research, project number 20-316-70009. References: Leslie, J. F., and Summerell, B. A. 2006. Page 224 in: The Fusarium Laboratory Manual. Blackwell, Oxford, UK. https://doi.org/10.1002/9780470278376 Leyronas, C., et al. 2018. Plant Dis. 102:2658 https://doi.org/10.1094/PDIS-06-18-0962-PDN Liu, Y.J. et al. 1999. Mol. Biol. Evol. 16: 1799 https://doi.org/10.1093/oxfordjournals.molbev.a026092 O'Donnell, K, et al. 1998a. Proc Natl Acad Sci USA. 95(5):2044. https://doi.org/10.1073/pnas.95.5.2044. O’Donnell, et al. 1998b. Mycologia 90:465 O’Donnell, K., et al. 2010. J. Clin. Microbiol., 48: 3708 https://doi.org/10.1128/JCM.00989-10 Snowdon, A. L. Pages 250–252 in: A Color Atlas of Post-Harvest Diseases and Disorders of Fruits and Vegetables. Vol. 1. 1990. Wolfe Scientific, London. Taylor, A, et al. 2013. Plant Pathol. 62:103. https://doi.org/10.1111/j.1365-3059.2012.02624.x White, T. J., et al. 1990. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA.