The occurrence of fungi on roots and stem bases of Triticum aestivum ssp. spelta L. Thell. grown under two levels of chemical protection and harmfulness of Fusarium graminearum Schwabe to seedlings of selected genotypes

Investigations were carried out in 2007–2009 on the plots of the Felin Experimental Station belonging to the University of Life Sciences in Lublin, Poland. The studies comprised two breeding lines of spelt wheat (Triticum aestivum ssp. spelta L. Thell.) – STH 3 and STH 715. Two levels of chemical protection were applied in the cultivation with minimal and complex protection. Infection of winter spelt wheat roots and stem bases was recorded in each growing season at hard dough stage (87 in Zadok’s scale). After 3 years of the study, the mean values of disease indexes for the analyzed spelt wheat lines in the experimental treatment with minimal protection were 28.53 and 40.30 respectively for STH 3 and STH 715. In the experimental combination with complex protection, after 3 years of the study the mean values of disease indexes ranged from 25.96 (STH 3) to 26.90 (STH 715). The mycological analysis showed that Fusarium spp., especially F. culmorum, caused root rot and necrosis of stem bases of spelt wheat in the experimental combination with minimal and complex protection. Moreover, Fusarium avenaceum and Bipolaris sorokiniana caused root rot and necrosis of stem bases of spelt wheat. Investigation carried out in a growth chamber on susceptibility of seedlings of three lines of spelt wheat (LO 2/09/n/2, LO 5/09/13/3, LO 5/09/5/4) to infection with Fusarium graminearum No. 8 and F. graminearum No. 45 showed that the genotypes did not differ in their susceptibility. All of them were susceptible, as indicated by high values of the disease indexes. No interaction was found between genotypes and strains of the fungus. This indicates the differential pathogenicity of Fusarium graminearum species

The varied ability of grains to synthesize and catabolize ABA is one of the factors affecting dormancy and its release by after-ripening in imbibed triticale grains of cultivars with different pre-harvest sprouting susceptibilities

Abscisic acid (ABA) is a phytohormone involved in acquisition of primary dormancy and dormancy maintenance in imbibed seeds. After imbibition, ABA content decreased to a much lower level in embryos of freshly harvested triticale grains of the Leontino cultivar, which is more susceptible to pre-harvest sprouting (PHS) than embryos of the Fredro cultivar. Lower ABA content in the Leontino cultivar resulted from increased expression of TsABA8’OH1 and TsABA8’OH2, which encode ABA 8’-hydroxylase and are involved in ABA catabolism. Higher ABA content and maintenance of dormancy in Fredro grains were correlated with intensified ABA biosynthesis, which resulted from higher expression of TsNCED1, which encodes 9-cis-epoxycarotenoid dioxygenase. These results suggest that grains of triticale cultivars with different resistance to PHS vary in their ability to metabolize ABA after imbibition. After-ripening did not affect the ABA content in embryos of dry grains of either triticale cultivar. However, after-ripening caused dormancy release in Fredro grains and significantly affected the ABA content and the rate of its metabolism after imbibition. A more rapid decline in ABA content in imbibed Fredro grains was accompanied by decreased transcript levels of TsNCED1 as well as increased expression of TsABA8’OH1 and TsABA8’OH2. Thus, after-ripening may affect dormancy of grains through reduction of the ABA biosynthesis rate and intensified ABA catabolism. Overexpression of TsNCED1 in tobacco increases ABA content and delays germination, while overexpression of TsABA8’OH2 decreases ABA content, accelerates germination, and reduces the sensitivity to ABA of transgenic seeds compared to seeds of wild-type plants. Therefore, these genes might play an important role in the regulation of triticale grain dormancy, thus affecting susceptibility to PH

Evaluation of Fusarium head blight resistance types in winter triticale using phenotypic and metabolic markers

Kolekcja 106 genotypów pszenżyta ozimego (X Triticosecale Wittmack) stanowiła materiał badawczy przeznaczony do oceny odporności na fuzariozę kłosów powodowaną przez Fusarium culmorum oraz akumulację toksyn fuzaryjnych w ziarnie. Doświadczenia inokulacyjne przeprowadzono w dwóch lokalizacjach. Określano indeks fuzariozy kłosów (IFK) będący miarą odporności typu I i II oraz procent ziarniaków z objawami fuzariozy (FDK; typ III odporności). Ziarniaki z wybranych genotypów analizowano pod względem zawartości toksyn fuzaryjnych (typ V odporności). Określano zawartość trichotecenów z grupy B: deoksyniwalenol (DON) i pochodne oraz niwalenol (NIV) oraz akumulację zearalenonu (ZEN). Badano również zawartość ergosterolu, będącego miernikiem zawartości grzybni w ziarnie. Porażenie kłosów pszenżyta ozimego (IFK) w obu lokalizacjach było zbliżone i kształtowało się średnio dla dwóch lokalizacji na poziomie 18,2%. Procent ziarniaków uszkodzonych przez Fusarium (FDK) był bardzo zróżnicowany dla badanych genotypów pszenżyta. Średnio wynosił 29,5% (FDK z masy) i 37,6% (FDK z liczby). Wykazano istotny współczynnik korelacji pomiędzy lokalizacjami biorąc pod uwagę uszkodzenie ziarniaków poszczególnych genotypów. Odnotowano brak korelacji porażenia kłosów z uszkodzeniem ziarniaków w lokalizacji Poznań i słabą, ale istotną statystycznie korelację w Radzikowie. Stwierdzono wysokie stężenie toksyn fuzaryjnych w ziarnie. Zawartość DON wynosiła średnio dla dwóch lokalizacji 8,649 mg/kg, a stężenie NIV — średnio 5,839 mg/kg. Zawartość ZEN wynosiła średnio dla dwóch lokalizacji 1,382 mg/kg. Wysoki współczynnik korelacji odnotowano pomiędzy zawartością DON a FDK z masy i z liczby ziarniaków. Istotne były współczynniki korelacji ergosterolu z uszkodzeniem ziarniaków oraz zawartością trichotecenów B w ziarnie. Analiza wielocechowa pozwoliła na zidentyfikowanie sześciu genotypów łączących różne typy odporności na fuzariozę kłosów.A collection of 106 genotypes of winter triticale (X Triticosecale Wittmack) was evaluated for resistance to Fusarium head blight caused by Fusarium culmorum and for toxin accumulation in grain. The inoculation tests were carried out in two locations. Fusarium head blight indexes (FHBi) describing combined type I and type II of resistance, the percentage of kernels with visible symptoms of Fusarium damage (FDK; type III of resistance) and the level of Fusarium toxins (type V of resistance) were evaluated. The content of the type B trichothecenes: deoxynivalenol (DON) and derivatives, nivalenol (NIV) and zearalenone (ZEN) in grain was analyzed. Moreover, the amount of ergosterol was evaluated to measure the level of Fusarium mycelium in grain. The FHB indexes were similar in both locations and on average amounted to 18.2%. The percentage of FDK varied for individual triticale genotypes. The average FDK was 29.5% (FDK weight) and 37.6% (FDK number). Regarding the FDK of respective genotypes, a significant level of correlation between locations was found. There was a lack of correlation between FHBi and FDK in Poznań, and in Radzików, a very weak, but significant correlation between FHBi and FDK was observed. The content of Fusarium toxins in the grain was very high. The average of DON content for both locations was 8.649 mg/kg. The average content of NIV was also high and amounted to 5.839 mg/kg. The average content of zearalenone was 1.382 mg/kg. High correlation coefficient for DON and FDK was found. Correlation coefficients between ergosterol and FDK, as well as, among ergosterol and sum of type B trichothecenes in grain were significant. The principal component analysis revealed six triticale genotypes combining a high level of resistance of different type