Mycotoxin Profile and Phylogeny of Pathogenic Alternaria Species Isolated from Symptomatic Tomato Plants in Lebanon

Abstract

The tomato is one of the most consumed agri-food products in Lebanon. Several fungal pathogens, including Alternaria species, can infect tomato plants during the whole growing cycle. Alternaria infections cause severe production and economic losses in field and during storage. In addition, Alternaria species represent a serious toxicological risk since they are able to produce a wide range of mycotoxins, associated with different toxic activities on human and animal health. Several Alternaria species were detected on tomatoes, among which the most important are A. solani, A. alternata, and A. arborescens. A set of 49 Alternaria strains isolated from leaves and stems of diseased tomato plants were characterised by using a polyphasic approach. All strains were included in the recently defined phylogenetic Alternaria section and grouped in three well-separated sub-clades, namely A. alternata (24 out of 49), A. arborescens (12 out of 49), and A. mali morpho-species (12 out of 49). One strain showed high genetic similarity with an A.limoniasperae reference strain. Chemical analyses showed that most of the Alternaria strains, cultured on rice, were able to produce alternariol (AOH), alternariol methyl ether (AME), altenuene (ALT) and tenuazonic acid (TA), with values up to 5634, 16,006, 5156, and 4507 mg kg−1, respectively. In addition, 66% of the strains were able to co-produce simultaneously the four mycotoxins investigated. The pathogenicity test carried out on 10 Alternaria strains, representative of phylogenetic sub-clades, revealed that they were all pathogenic on tomato fruits. No significant difference among strains was observed, although A. alternata and A. arborescens strains were slightly more aggressive than A. mali morpho-species strains. This paper reports new insights on mycotoxin profiles, genetic variability, and pathogenicity of Alternaria species on tomatoes.

Biodiversity of Pathogenic and Toxigenic Seed-Borne Mycoflora of Wheat in Egypt and Their Correlations with Weather Variables

“…Our results revealed that both S. globuliferum and S. vesicarium are closely related to Alternaria spp., but phylogenetically they were distinct from each other. This result is consistent with the finding obtained by Habib et al [38].…”

Phylogeny and mycotoxin profiles of pathogenic Alternaria and Curvularia species isolated from date palm in southern Tunisia

“…For each gene, PCR mixture (15 μl) containing approximately 15–20 ng of DNA template, 1.5 μl (10X) PCR solution buffer, 0.45 μl of each primer (10 mM), 1.2 μl dNTPs (2.5 mM), and 0.125 μl of Hot Start Taq DNA Polymerase (1 U/μL; Fisher Molecular Biology, Trevose, Pennsylvania, US) was amplified. Amplification of Alt-a1 and gpd genes was performed with the primer pairs alt-for/alt-rev ( Hong et al, 2005 ), gpd1/gpd2 ( Berbee et al, 1999 ) using PCR reaction parameters as reported by Masiello et al (2019) , CaM gene was amplified using the PCR conditions reported by Habib et al (2021) .…”

“…In addition to the above mentioned species, other species have been associated with leaf blight in Tunisia. Ben Chobba et al ( 2013) identified also A. gaisen (included in Alternaria Section) by using ITS1 and ITS4 genes, whereas Namsi et al (2021) identified A. mali, by using ITS, gpd, CaM, and Alt-a1 genes. However, in other studies, A. mali was proposed as synonymous to A. alternata species (Woudenberg et al, 2015), whereas, according to Somma et al (2019), A. mali was phylogenetically more similar to A. gaisen, both species being distinguishable from A. alternata.…”

Alternaria species and related mycotoxin detection in Lebanese durum wheat grain

“…Genomic DNA was extracted and purified from 2-d-old colonies grown on cellophane disks overlaid on PDA at 25±1°C (Habib et al, 2021).…”