Study of Fungal Colonization of Wheat Kernels in Syria with a Focus on Fusarium Species

Dima Alkadri,Paola Nipoti,Annamaria Pisi,Katharina Döll,Antonio Prodi,Petr Karlovsky

doi:10.3390/ijms14035938

Abstract

Wheat is one of the main crops in Mediterranean countries, and its cultivation has an important role in the Syrian economy. In Syria, Fusarium head blight (FHB) has not been reported so far. Mycological analysis of 48 samples of wheat kernels collected from cultivation areas with different climatic conditions were performed in 2009 and 2010. Fungal isolates were identified at the genus level morphologically; Fusarium species were characterized morphologically and by species-specific PCR. The most frequent fungal genera found were Alternaria spp. and Cladosporium spp., with frequencies of 24.7% and 8.1%, respectively, while the frequency of Fusarium spp. was 1.5% of kernels. Most frequent Fusarium species were F. tricinctum (30% of all Fusarium isolates), F. culmorum (18%), F. equiseti (14%) and F. graminearum (13%). The mycotoxin production potential of selected Fusarium isolates was assessed by HPLC-MS analysis of rice cultures; chemotyping by PCR was carried out for comparison. All six F. graminearum strains tested produced small amounts (<3 mg/kg) of nivalenol (NIV). All ten F. culmorum strains tested produced large amounts of trichothecenes (>100 mg/kg); four strains produced NIV and six strains produced deoxynivalenol (DON) and 3-acetyl-deoxynivalenol (3Ac-DON). PCR chemotyping lead to an oversimplified picture, because all 3Ac-DON chemotype strains produced more DON than 3Ac-DON; furthermore, the strongest NIV producers produced significant amounts of DON. All tested strains of F. culmorum, F. graminearum, F. pseudograminearum (two strains) and most F. equiseti strains (five of six strains) produced zearalenone. Grains of durum wheat were more frequently colonized by Fusarium spp. than grains of soft wheat. Incidence of Fusarium spp. in irrigated fields was higher than in rainfed fields. The incidence of Fusarium strains producing mycotoxins raises concerns about the risk of Fusarium head blight to Syria and its consequences for public health.

Highlights

Durum wheat constitutes the largest part of the staple food in the southern Mediterranean countries [1]
In the surveys carried out in 2009 and 2010 on durum and soft wheat grains collected from different provinces in Syria, 17 different genera of fungi were identified in surface-disinfected kernels
Our study indicates the dominance of F. tricinctum in Syrian wheat

Summary

Introduction

Durum wheat constitutes the largest part of the staple food in the southern Mediterranean countries [1]. In Syria, wheat cultivation covers 83% of the cultivated area and has a central role in the diet [2]. There are five distinct agro-climatic zones in Syria based on rainfall (Figure 1) [3]. Wheat is present in all these areas. Rainfed wheat is concentrated in high rainfall zones 1 and 2, while irrigation is necessary in zones 3, 4 and 5. The largest zones are 5, 1 and 2, covering 53%, 42% and 40% of the total cultivated land, respectively [4]

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Conclusion