Induction of Fusarium lytic Enzymes by Extracts from Resistant and Susceptible Cultivars of Pea (Pisum sativum L.)

Abstract

Being pathogenic fungi, Fusarium produce various extracellular cell wall-degrading enzymes (CWDEs) that degrade the polysaccharides in the plant cell wall. They also produce mycotoxins that contaminate grains, thereby posing a serious threat to animals and human beings. Exposure to mycotoxins occurs through ingestion of contaminated grains, inhalation and through skin absorption, thereby causing mycotoxicoses. The toxins weaken the host plant, allowing the pathogen to invade successfully, with the efficiency varying from strain to strain and depending on the plant infected. Fusariumoxysporum predominantly produces moniliformin and cyclodepsipeptides, whereas F. proliferatum produces fumonisins. The aim of the study was to understand the role of various substrates and pea plant extracts in inducing the production of CWDEs and mycotoxins. Additionally, to monitor the differences in their levels when susceptible and resistant pea plant extracts were supplemented. The cultures of F. proliferatum and F. oxysporum strains were supplemented with various potential inducers of CWDEs. During the initial days after the addition of substrates, the fungus cocultivated with pea extracts and other carbon substrates showed increased activities of β-glucosidase, xylanase, exo-1,4-glucanase and lipase. The highest inhibition of mycelium growth (57%) was found in the cultures of F. proliferatum strain PEA1 upon the addition of cv. Sokolik extract. The lowest fumonisin content was exhibited by the cultures with the pea extracts and oat bran added, and this can be related to the secondary metabolites and antioxidants present in these substrates.

Dynamics of Fusarium Mycotoxins and Lytic Enzymes during Pea Plants’ Infection

“…Although the current study does not demonstrate a direct role of any studied enzyme, it provides the basis for such research. Our previous [9] and current studies prove that the selected strains behave differently when added to the extracts of susceptible and resistant host phenotypes. The extracts from susceptible cultivars induce sudden increases in the lytic gene expression in the pathogen, whereas resistant cultivars elicit slow and reduced expressions.…”

“…The fungal strains were selected based on the results from the enzymatic activities carried out previously [9]. One strain each of F. proliferatum (PEA2) and F. oxysporum (1757OX) were used for the fungal gene expression studies.…”

“…Morphological parameters such as the structures of hyphae, phialides and conidia and a molecular analysis using TEF-1α and ITS1-ITS2-specific primers were used for identification [44]. The strains were selected based on the previously carried out mycotoxin production studies [9]. The PDA-grown 7-day-old cultures were added to 48 mL of the fumonisin-inducing media for the mycotoxin analysis [45].…”

“…It was found that pea extracts could reduce the biosynthesis of group B fumonisins and could limit the fungal biomass in F. proliferatum [8]. Our previous report showed that the extracts from the resistant pea variety Sokolik accumulate less/no fumonisin B 1 and B 2 in F. proliferatum strain PEA1 when compared to the susceptible variety Santana [9]. Additionally, the Sokolik extract could also considerably reduce the biomass of both F. proliferatum and F. oxysporum.…”

Capacidad de infección de hongos asociados a la pudrición seca de los Tubérculos de Ñame

“…Además, se debe establecerse una compatibilidad del huésped-patógeno como requisito primario para que se dé una invasión y destrucción del huésped por un agente patógeno, dando como resultado la compatibilidad genética entre enzimas hidrolíticas y los tejidos constitutivos del hospedador (Mabou et al, 2020), esto puede confirmar la capacidad de infección que tienen los morfotipos DH2, DH11, DH20 y DH17 por los tubérculos de ñame espino. Algunos autores sugieren que los cambios ambientales, pueden estimular a que algunos hongos se conviertan en patógenos agresivos, a través de la liberación de enzimas degradantes, proteínas inhibitorias y toxinas (Gonçalves et al, 2019;Perincherry et al, 2020).…”