Resistance to Fusarium Head Blight, Kernel Damage, and Concentrations of Fusarium Mycotoxins in the Grain of Winter Wheat Lines

Fusarium head blight (FHB) can contaminate cereal grains with mycotoxins. Winter wheat can also become infected with FHB and is more resistant than durum wheat to head infection but less than other small-grain cereals. The aim of this study was to identify winter wheat lines that combine low levels of head infection and kernel damage with low levels of grain contamination with mycotoxins. Resistance of 27 winter wheat lines (four with resistance gene Fhb1) and cultivars to FHB was evaluated over a three-year (2017–2019) experiment established in two locations (Poznań and Radzików, Poland). At the anthesis stage, heads were inoculated with Fusarium culmorum isolates. The FHB index was scored, and the percentage of Fusarium-damaged kernels (FDKs) was assessed. The grain was analyzed for type B trichothecenes (deoxynivalenol and derivatives and nivalenol) and zearalenone content. The average FHB index of both locations was 12.9%. The proportion of FDK was 6.9% in weight and 8.5% in number. The average content of deoxynivalenol amounted to 3.543 mg/kg, and the average amount of nivalenol was 2.115 mg/kg. In total, we recorded 5.804 m/kg of type B trichothecenes. The zearalenone content in the grain was 0.214 mg/kg. Relationships between the FHB index, FDK, and mycotoxin contents were highly significant for wheat lines; however, these relationships were stronger for FDK than for FHB index. Breeding lines combining all types of FHB resistance were observed, five of which had resistance levels similar to those of wheat lines with the Fhb1 gene

Resistance to Fusarium Head Blight, Kernel Damage, and Concentration of Fusarium Mycotoxins in Grain of Winter Triticale (x Triticosecale Wittmack) Lines

Fusarium head blight (FHB) can cause contamination of cereal grain with mycotoxins. Triticale is also infected with FHB; however, it is more resistant than wheat to head infection. The aim of this study was to identify triticale lines that combine low head infection with low toxin contamination. Resistance to FHB of 15 winter triticale and three winter wheat lines was evaluated over a three-year experiment established in two locations. At the anthesis stage, heads were inoculated with Fusarium culmorum isolates. The FHB index was scored and the percentage of Fusarium-damaged kernels (FDKs) assessed. The grain was analysed for type B trichothecenes (deoxynivalenol and derivatives, nivalenol) and zearalenone content. The average FHB index was 10.7%. The proportion of FDK was 18.1% (weight) and 21.6% (number). An average content of deoxynivalenol amounted to 7.258 mg/kg and nivalenol to 5.267 mg/kg. In total, it was 12.788 mg/kg of type B trichothecenes. The zearalenone content in the grain was 0.805 mg/kg. Relationships between FHB index, FDK, and mycotoxin contents were statistically significant for triticale lines; however, they were stronger for FDK versus mycotoxins. Triticale lines combing all types of FHB resistance were found, however the most resistant ones were less resistant that wheat lines with the Fhb1 gene

Impairment of Meristem Proliferation in Plants Lacking the Mitochondrial Protease AtFTSH4

Shoot and root apical meristems (SAM and RAM, respectively) are crucial to provide cells for growth and organogenesis and therefore need to be maintained throughout the life of a plant. However, plants lacking the mitochondrial protease AtFTSH4 exhibit an intriguing phenotype of precocious cessation of growth at both the shoot and root apices when grown at elevated temperatures. This is due to the accumulation of internal oxidative stress and progressive mitochondria dysfunction. To explore the impacts of the internal oxidative stress on SAM and RAM functioning, we study the expression of selected meristem-specific (STM, CLV3, WOX5) and cell cycle-related (e.g., CYCB1, CYCD3;1) genes at the level of the promoter activity and/or transcript abundance in wild-type and loss-of-function ftsh4-1 mutant plants grown at 30 °C. In addition, we monitor cell cycle progression directly in apical meristems and analyze the responsiveness of SAM and RAM to plant hormones. We show that growth arrest in the ftsh4-1 mutant is caused by cell cycle dysregulation in addition to the loss of stem cell identity. Both the SAM and RAM gradually lose their proliferative activity, but with different timing relative to CYCB1 transcriptional activity (a marker of G2-M transition), which cannot be compensated by exogenous hormones

Use of molecular and phenotypic markers to identify wheat eyespot resistance genes caused by Oculimacula yallundae and O. acuformis

Łamliwość źdźbła to jedna z ważniejszych chorób pszenicy uprawnej (Triticum aestivum L.) powodowana przez dwa grzyby patogeniczne Oculimacula yallundae i Oculimacula acuformis. Istnieje kilka źródeł odporności na ten patogen, lecz jak dotąd tylko dwa geny Pch1 i Pch2 zostały przniesione do pszenicy uprawnej i warunkują odporność. Wybranie najkorzystniejszych markerów molekularnych dla określenia obecności genów odporności na łamliwość źdźbła u pszenicy może poprawić skuteczność i dokładność przy wyborze genotypów odpornych na tę chorobę. Celem pracy było określenie efektywności markerów molekularnych i markera izoenzymatycznego dla genów Pch1 i Pch2 oraz wytypowanie genotypów pszenicy ozimej o podwyższonej odporności w odniesieniu do porażenia roślin w testach inokulacyjnych przeprowadzonych w fazie siewki oraz rośliny dojrzałej. Materiał badawczy stanowiło 159 linii hodowlanych pszenicy ozimej oraz pięć odmian kontrolnych: Artist, Kilimanjaro, Kometa, Patras i Rendezvous. Do identyfikacji genów odporności wykorzystano pięć markerów, trzy do identyfikacji genu Pch1 (EpD1b, XustSSR2001-7DL, Xorw1) oraz dwa dla genu Pch2 (Xcfa2040, Xwmc525). Biorąc pod uwagę analizę molekularną genów, wyniki inokulacji siewek oraz wyniki porażenia źdźbeł dojrzałych roślin, stwierdzono brak objawów porażenia źdźbeł u linii/odmian pszenicy ozimej, u których zidentyfikowano oba geny Pch1 i Pch2. Stwierdzono u nich również najniższe porażenie siewek. Najwyższy procent porażonych źdźbeł odnotowano u genotypów, gdzie nie stwierdzono genów Pch1 i Pch2. U tych genotypów zaobserwowano również najwyższe porażenie w teście siewkowym. Wykazano, że obecność genów Pch1 i Pch2 lub ich brak nie wpływała istotnie na plon ziarna oraz na masę tysiąca ziarniaków (MTZ). U genotypów z genami Pch1 i Pch2 stwierdzono nieznacznie wyższe wartości dla obu parametrów technologicznych.  Eyespot is one of the most important diseases of wheat (Triticum aestivum L.), caused by two pathogenic fungi Oculimacula yallundae and Oculimacula acuformis. There are several sources of resistance to this pathogen, but so far only two genes Pch1 and Pch2 have been transferred to wheat and confer the resistance. The selection of the most favorable genetic markers for determining the presence of eyespot resistance genes may improve the efficiency and accuracy in the selection of wheat genotypes resistant for this disease. The aim of the work was to determine the effectiveness of molecular markers and protein marker for Pch1 and Pch2 genes and to select genotypes of winter wheat with increased resistance in relation to plant infection in inoculation tests carried out at the seedling and adult plant stage. Plant material consist of 159 breeding lines of winter wheat and five control varieties: Artist, Kilimanjaro, Kometa, Patras and Rendezvous. To identify resistant genes, five molecular markers were used. Three for Pch1 gene (EpD1b, XustSSR2001-7DL, Xorw1) and two for Pch2 gene (Xcfa2040, Xwmc525). Considering the molecular analysis of genes, results of seedlings inoculation and the results of plant stem infestation, it was found that there were no infection symptoms of stalks in the winter wheat lines and/or varieties, in which both Pch1 and Pch2 genes were identified. In these lines/varieties, the lowest infection of seedlings was also observed. The highest percentage of infected sheaths was identified in genotypes where Pch1 and Pch2 genes were not found. The highest seedling infection was also observed for these genotypes. It was shown that the presence of Pch1 and Pch2 genes or their absence did not significantly affect the grain yield and the thousands kernels weight (TKW). Genotypes with the Pch1 and Pch2 genes showed slightly higher values for both technological parameters.