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A complex of Fusarium spp. causes Fusarium head blight (FHB) on wheat and also on barley. Infection with FHB results not only in yield loss, but also causes depreciation of the harvested product due to the accumulation of toxins such as deoxynivalenol produced by Fusarium spp. The flowering time is a very susceptible period for primary infection. One reason might be that during this period spores can get into the opened wheat florets where they may later cause infection. Initial symptoms of infection of a wheat ear are visible whitening and drying of individual spikelets or entire parts of the ear. If the florets became infected shortly after blooming, grains are often not formed, while other infected spikelets have grains with various deformities, shrunken and with pink-white coloration (Klem & Tvarůžek 2005). The main aim of experiments was detection of Fusarium species on wheat grains by using of the PCR methods. Abstract Nedělník J., Moravcová H., Hajšlová J., Lancová K., Váňová M., Salava J. (2007): Fusarium spp. in wheat grain in the Czech Republic analysed by PCR method. Plant Protect. Sci., 43: 135-137. The frequency of occurrence of four Fusarium spp. on wheat in the Moravia region, Czech Republic, was determined by polymerase chain reaction (PCR). Grain samples were collected during 2003-2006 at grain purchase centres. The dominant species was F. graminearum, which was recorded in all samples of the first 3 years of the study and in 88% of them in 2006. The previously more frequent F. culmorum was detected in 100% of the samples only in 2005; in the preceding two years the frequency of its detection was lower, 84% and 60%, and in 2006 it was detected in 55% of the samples. Fusarium avenaceum had a very low occurrence in the years 2003-2004, but in 2005 it was recorded in 100% of the samples. In 2006 it was the opposite-total absence of this species. A quite different situation was found in the occurrence of the fourth species-F. poae. In the years 2005 and 2006 it was only detected in 10%, resp. 2% of the samples, compared to markedly higher occurrences in the previous years. A comparison of the current weather development with the long-term mean at the Troubsko locality suggests that years with a relatively long, wet and cold start of the growing season and warmer end of vegetation (late May-July) will favour F. graminearum.

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Mycotoxin content in 244 samples of wheat ears randomly collected during 2014 and 2015 from various localities in the Czech Republic was analysed using liquid chromatography coupled to mass spectrometry (LC-MS). Mean mycotoxin concentration in 2014 was highest for deoxynivalenol (DON; 760 μg/kg), followed by zearalenone (ZEA; 115 μg/kg), 3-acetyldeoxynivalenol (3-ADON; 88 μg/kg), deoxynivalenol-3-glucoside (83 μg/kg), and enniatins (ENNs; 102 μg/kg). In 2015, DON (66 μg/kg) also had the highest concentration level, followed by ENNs (35 μg/kg), nivalenol (2 μg/kg), and beauvericin (2 μg/kg). The maximum limit for DON in the European Union (1,250 μg/kg) was exceeded in 2% of samples, and the maximum limit for ZEA (100 μg/kg) was exceeded in 0.8% of samples. Fusarium species causing head blight were identified using PCR assays. During 2014-2015, Fusarium poae considerably dominated (48.7% average value of occurrence in the samples). Other species were detected in much lower frequencies in both years: Fusarium graminearum (average frequency of occurrence 13.7%), Fusarium avenaceum (11.9%), Fusarium culmorum (4.2%), and Fusarium equiseti (2.9%). Fusarium langsethiae was identified only in 2015, at a frequency of 10.2%, and Fusarium sporotrichioides was present only sporadically in 2014.

Multiplex PCR was developed and optimized for simultaneous detection of wheat leaf rust resistance genes Lr26 and Lr37. The presence of the genes was analyzed in 21 winter wheat cultivars registered in the Czech Republic. Gene Lr37 was detected in four tested cultivars (Bakfis, Biscay, Nicol, Mulan), gene Lr26 occurred only in one cultivar (Etela) and three cultivars (Clarus, Orlando and Rapsodia) were found to carry both these genes. Data obtained by PCR markers were compared with results of greenhouse and field tests. Seedling reactions of cultivars possessing Lr26 to seven different leaf rust isolates conformed to the results obtained by the marker analysis, however, there were found some discrepancies in the detections of Lr37, which could be detected in greenhouse seedling tests only with difficulties.

Twenty-seven winter wheat cultivars registered in the Czech Republic were tested by molecular markers for the presence of Lr26 and Lr37, and twenty-eight cultivars for the presence of Lr10. Gene Lr37 was determined in eleven cultivars, gene Lr10 in ten cultivars and gene Lr26 in four cultivars. Eight cultivars had combinations of two Lr genes, one cultivar possessed all the three Lr genes. The results of marker analyses were compared with multipathotype analysis which confirmed the presence of Lr26 but did not enable the verification of the presence of Lr10 and Lr37. Seedling resistance was compared with resistance of the studied cultivars in the field.

Abstract:In 2009-2011 virulence of the wheat leaf rust population was studied on Thatcher near-isogenic lines with Lr1, Lr2a, Lr2b, Lr2c, Lr3a, Lr9, Lr11, Lr13, Lr15, Lr17, Lr19, Lr21, Lr23, Lr24, Lr26 and Lr28. Samples of leaf rust were obtained from different parts of the Slovak Republic. A total of 122 wheat leaf rust isolates were analysed. Resistance gene Lr19 was effective to all tested isolates. Virulence to Lr9 was found, however only in one isolate. Gene Lr24 conditioned resistance to almost all rust collections. A lower frequency of virulence to Lr2a and Lr28 was also observed. Nineteen winter wheat cultivars grown in Slovakia were tested with 8 leaf rust isolates. Winter wheat cultivar Bona Dea was resistant to all isolates applied in the greenhouse test. Presence of Lr genes was estimated according to the reactions of the tested cultivars. Presence of Lr10, Lr26, Lr34 and Lr37 was studied by molecular markers.

In 2013-2015 virulence in the wheat leaf rust population was evaluated on 17 Thatcher near-isogenic lines with leaf rust resistance genes. A total of 110 wheat leaf rust isolates were analyzed. Resistance genes Lr9 and Lr19 were effective to all tested isolates. Genes Lr24 and Lr28 conditioned resistance to 92% of the tested rust isolates. Thirty-seven winter wheat cultivars registered in Slovakia were analyzed for the presence of Lr10, Lr24, Lr26, Lr34 and Lr37 using tightly linked molecular markers. Gene Lr37 was the most common in the tested cultivars. Leaf rust resistance was also tested in 13 wheat cultivars at the seedling stage with representative pathotypes of leaf rust.