The richness of Fusarium species in maize tassels and their relationship with Fusarium stalk rot

Abstract

Abstract: The presence of toxigenic fungi of the genus Fusarium can cause negative effects on grain yield and the quality of maize (Zea mays L.). This study aimed to analyze the diversity of Fusarium spp. on tassel during the silking stage as a possible source of inoculum and their potential relationship with Fusarium stalk rot. Field experiments were carried out during two growing seasons in Azul, Argentina, which included 12 commercial hybrids of maize. The diversity of Fusarium species isolated from tassels was analyzed by visualizing morphological characteristics and confirming them using molecular techniques. Subsequently, an experiment was carried out under greenhouse conditions to evaluate the pathogenicity of the Fusarium species isolated from the tassels on stalk of two maize hybrids (H1 and H2). Fusarium verticillioides (74%) was the most frequent Fusarium species isolated from maize tassels, followed by species of F. incarnatum-equiseti species complex (17%). Other species, such as F. proliferatum (4%), F. subglutinans (3%), F. graminearum (1%), and F. sporotrichioides (1%), were found in less quantity. With regards to stalk pathogenicity, all Fusarium isolates used as inoculum developed stalk rot symptoms in both hybrids, with H2 the most affected (1.08 ± 0.90 cm2 vs. 0.52 ± 0.57 cm2). Our work demonstrated that the presence of the most frequent species of Fusarium isolated from maize ear on tassels would be a possible source of inoculum for maize-stalk rot infection. Moreover, the capacity of the selected isolates to produce stalk rot symptoms was studied. This information could be useful to predict which mycotoxins will be found in maize grains, inferring potential risks for the consumer and food safety. Graphical abstract: [Figure not available: see fulltext.].