Toxins of micromycetes in generative organs of plants of the family Fabaceae

During the study of the role of associated microscopic fungi in the adaptation of plants to external influences, researchers focus mainly on such key aspects as i) the shift in the composition of the internal mycobiota during growth, ii) the direction of fungal colonization of vegetative and generative organs, and iii) concomitant changes in the metabolic status of the plant organism (J.A., Wearn et al., 2012; V. Arbona et al., 2013; J. Hong et al., 2016). The dynamics of DNA accumulation of Alternaria , Cladosporium and Fusarium fungi in different months of plant growth was revealed in meadow grasses of the Fabaceae family (O.P. Gavrilova et al., 2017; A.S. Orina et al., 2018) and seasonal fluctuations in the content of toxic metabolites characteristic of these groups of micromycetes were found (A.A. Burkin, G.P. Kononenko, 2018, 2019). The predominant localization of mycotoxins in leaves was established for meadow clover, white clover, Caucasian goat’s rue, Washington lupine and melilot (G.P. Kononenko et al., 2019). In this study, we describe for the first time the complexes of toxic fungi metabolites in the generative organs of legumes. The aim of the work was to study the component composition and content of mycotoxins in the whole plants, flowers and beans of perennial legumes of 6 genera of the Fabaceae family. Meadow grasses of the genera Trifolium L. - meadow clover ( T. pratense L.), alsike clover ( T. hybridum L.), zigzag clover ( T. medium L.), white clover ( T. repens L.); of Lathyrus L. - meadow peavine ( L. pratensis L.), spring peavine ( L. vernus (L.) Bernh.); of Vicia L. - bush vetch ( V. sepium L.), cow vetch ( V. cracca L.); of Lotus L. - deer vetch ( L. corniculatus L. s.l.); of Lupinus L. -Washington lupine ( L. polyphyllus Lindl.), and of Galega L. - Caucasian goat’s rue ( G. orientalis Lam.) were collected from natural grass stands of the Moscow region in May-the first half of August 2019, wood vetch ( V. sylvatica L.) and Japanese peavine ( L. japonicus Willd. subsp. pubescens Korobkov) - in the second half of August of the same year on of the Kandalaksha Gulf of the White Sea (Republic of Karelia). The aboveground parts of plants, as well as flowers and beans, were kept at room temperature to an air-dry state and crushed in a laboratory mill. For extraction, a mixture of acetonitrile and water was used (84:16 v/v) at the ratio of 10 ml per 1 g of the sample. Extracts after 10-fold dilution with a buffer solution were assessed using indirect competitive enzyme immunoassay. The content of the mycotoxins - T-2 toxin (T-2), deoxynivalenol (DON), zearalenone (ZEN), fumonisins (FUM), ergot alkaloids (EA), alternariol (AOL), roridin A (ROA), aflatoxin B1 (AB1), sterigmatocystin (STE), cyclopiazonic acid (CPC), emodin (EMO), ochratoxin A (OA), citrinin (CIT), mycophenolic acid (IFC), PR-toxin (PR) was determined using commercial and research certified enzyme immunoassay systems (GOST 31653-2012). For the generative organs of most of the examined plants, both common features (preservation of the mycotoxin profile typical of the whole plant, with the absence or decrease in the content of a number of fungal metabolites) and peculiarities were revealed. In particular, in the flowers of three species of the genus Trifolium L., in general, the mycotoxin complex characteristic of the vegetative part was preserved, but the occurrence and accumulation of fusariotoxins were higher. The flowers of two species - alsike clover and zigzag clover were characterized by combined contamination of OA and CIT in comparable quantities, rare for plants. With a general low contamination, fusariotoxins T-2, DON and ZEN were present only in generative organs in the deer vetch. In all representatives of the genera Vicia , Lathyrus , Lupinus , and Galega the metabolic background in flowers as a whole was found weakened, in beans it turned out to be similar to the aboveground part without a sharp variation in the content of mycotoxins.