Pathogenic and Genetic Characterization of Fusarium verticillioides Strains Collected from Maize and Sorghum Kernels

Abstract

Commercial and sanitary qualities of cereals are important and contribute to the determination of the final application and destination of the grain and, thus, farmer profit. Although considered a minor crop in Italy, in the last years, the cultivation area of sorghum (Sorghum bicolor L. Moench) has been increasing and is often adjacent or subsequent to the most common maize (Zea mays L.) fields, with the risk of sharing mycotoxigenic fungi that are common to both cereals, such as Fusarium verticillioides. The present work aims to clarify if a fungal physiological characteristic such as fumonisin production and some plant growth parameters such as effects on germination, root and shoot development and on tissue necrosis may be common and shared among F. verticillioides strains belonging to maize and sorghum, especially if present on adjacent fields at the same time. Sorghum kernels are commonly less colonized and contaminated by F. verticillioides and fumonisins than maize, and, at least in part, this aspect could be explained by the higher frequency of low-producing strains obtained from sorghum compared to those obtained from maize. Moreover, although no clear pathogen specificity was found, the results relating to the parameters analyzed suggest a host preference by F. verticillioides isolated from maize that affects maize seedlings with greater severity as well as F. verticillioides strains from sorghum versus sorghum. Five microsatellite markers showed minor differences between the two sets of strains but could not reliably discriminate between hosts. The resulting data suggest that in adjacent maize and sorghum crops, the population of F. verticillioides selected during sorghum cultivation may not represent a particular mycotoxigenic or pathogenic issue for maize cultivation.