Alternaria in malting barley: characterization and distribution in relation with climatic and barley cultivars

CASTAÑARES E.; DA CRUZ CABRAL L.; DINOLFO M.I.; ANDERSEN B.; STENGLEIN S.A.; PATRIARCA A.

INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2021

0168-1605

Alternaria is one of the main fungal genera affecting the quality of barley grains. In this study, a polyphasic approach was carried out to characterise the Alternaria population infecting different cultivars of barley grains from the major producing regions of Argentina in the 2014 and 2015 seasons. Its relationship with Fusarium and correlations between predominant species, barley cultivars, and climatic conditions in the growing regions were evaluated. All barley cultivars examined were contaminated with Alternaria spp., and their incidence was higher in the driest season (21 % in 2014 and 42% in 2015). Fusarium incidence was much lower (6 and 4 %, respectively), regardless growing season, barley cultivar, or geographic region, and no significant correlation between the two fungal genera was observed.The dominant Alternaria species-group isolated and identified based on morphological characteristics, DNA sequencing, and metabolite profile was A. tenuissima (72.9 %), followed by A. infectoria (14.6 %). An association between their frequency and field temperature was observed; A. tenuissima sp.-grp. was more frequent in northern localities, where higher temperatures were registered, while the opposite was observed for A. infectoria sp.-grp. A smaller percentage of A. arborescens sp.-grp. (5 %), A. alternata sp.-grp. (3.9 %) and A. vaccinii (1.4 %) were also identified.Both secondary metabolite profiles and phylogenetic analysis were useful to distinguish isolates from Alternaria section Alternaria and section Infectoriae. Regarding metabolite profiles, alternariol was the most frequent compound produced by isolates of the section Alternaria. Infectopyrones and novae-zelandins were produced by most of the isolates from section Infectoriae. The results obtained in the present study will be a valuable tool for health authorities to assess the need for regulations on Alternaria mycotoxins, given the high incidence of Alternaria spp. in barley and the diversity of metabolites that might contaminate the grains.