Alternaria in malting barley: Characterization and distribution in relation with climatic conditions 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 vol. 357

0168-1605

Alternaria is one of the main fungal genera affecting the quality of barley grains. In this study, a polyphasic approachwas carried out to characterise the Alternaria population infecting different cultivars of barley grainsfrom the major producing regions of Argentina in the 2014 and 2015 seasons. Its relationship with Fusarium andcorrelations between predominant species, barley cultivars, and climatic conditions in the growing regions wereevaluated.Alternaria incidence exceeded that of Fusarium in all the barley samples and was higher in the drier season(21% in 2014 and 42% in 2015 vs. 6% and 4%, respectively). The main Alternaria species-groups identified werepresent in both growing seasons in similar frequencies (A. tenuissima sp.-grp., 83.4% in 2014 and 81.7% in 2015;A. infectoria sp.-grp., 11.7% in 2014 and 11.3% in 2015). The dominant Alternaria species-group isolated andidentified 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 wasobserved; 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 Alternariasection Alternaria and section Infectoriae. Regarding metabolite profiles, alternariol was the most frequentcompound produced by isolates of the section Alternaria. Infectopyrones and novae-zelandins were producedby most of the isolates from section Infectoriae.The barley cultivars analysed in this study did not show a particular susceptibility regarding the Alternariapopulation composition, except for Andreia, which presented the highest frequency of contamination with A.tenuissima sp.-grp. The rest of the cultivars, when grown in different regions, showed different proportion of theAlternaria sp.-grps., suggesting that other factors were determinant in their distribution.The results obtained in the present study will be a valuable tool for health authorities to assess the need for regulationson Alternaria mycotoxins, given the high incidence of Alternaria spp. in barley and the diversity ofmetabolites that might contaminate the grains.