ena-STUDY-ISPA-13-07-2021-14:02:02:264-64
Alternaria species isolated from tomato plants in Lebanon
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 to different toxic activities on human and animal health. Several Alternaria species were detected on tomato, 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 characterized 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 (12 out of 49). One strain showed high genetic similarity with A. limoniasperae reference strain. Chemical analyses showed that most of 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, 16006, 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 strains. This paper reports new insights on mycotoxin profile, genetic variability and pathogenicity of Alternaria species, such as the lack of occurrence of A. solani on tomato.
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 to different toxic activities on human and animal health. Several Alternaria species were detected on tomato, 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 characterized 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 (12 out of 49). One strain showed high genetic similarity with A. limoniasperae reference strain. Chemical analyses showed that most of 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, 16006, 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 strains. This paper reports new insights on mycotoxin profile, genetic variability and pathogenicity of Alternaria species, such as the lack of occurrence of A. solani on tomato.