Characteristics of the Infection of Tilletia laevis Kühn (syn. Tilletia foetida (Wallr.) Liro.) in Compatible Wheat

<i>Tilletia laevis</i> Kühn (syn. <i>Tilletia foetida</i> (Wallr.) Liro.) causes wheat common bunt, which is one of the most devastating plant diseases in the world. Common bunt can result in a reduction of 80% or even a total loss of wheat production. In this study, the characteristics of <i>T. laevis</i> infection in compatible wheat plants were defined based on the combination of scanning electron microscopy, transmission electron microscopy and laser scanning confocal microscopy. We found <i>T. laevis</i> could lead to the abnormal growth of wheat tissues and cells, such as leakage of chloroplasts, deformities, disordered arrangements of mesophyll cells and also thickening of the cell wall of mesophyll cells in leaf tissue. What’s more, <i>T. laevis</i> teliospores were found in the roots, stems, flag leaves, and glumes of infected wheat plants instead of just in the ovaries, as previously reported. The abnormal characteristics caused by <i>T. laevis</i> may be used for early detection of this pathogen instead of molecular markers in addition to providing theoretical insights into <i>T. laevis</i> and wheat interactions for breeding of common bunt resistance.

Effects of Tilletia foetida on Microbial Communities in the Rhizosphere Soil of Wheat Seeds Coated with Different Concentrations of Jianzhuang

Tilletia foetida (syn. T. laevis) leads to wheat common bunt, a worldwide disease that can lead to 80% yield loss and even total loss of production, together with degrading the quality of grains and flour by producing a rotten fish smell. To explore the potential microbial community that may contribute to the control of soil- and seed-borne pathogens, in this study, we analyzed the effects of the plant pathogenic fungus T. foetida on rhizosphere soil microorganisms in wheat seeds coated with different concentrations of a fungicide (Jianzhuang) used to control the disease. To analyze the bacterial and fungal abundance in T. foetida-infected and mock-infected plants, the microorganisms were sequenced using high-throughput HiSeq 2500 gene sequencing. The results showed that bacterial communities, including Verrucomicrobia, Patescibacteria, Armatimonadetes, Nitrospirae, Fibrobacteres, Chlamydiae, and Hydrogenedentes, and fungal communities, including Basidiomycota and Ciliophora, were more prevalent in the mock group than in the T. foetida-infected group, which may contribute to the control of wheat common bunt. Moreover, cluster and PCoA analysis revealed that replicates of the same samples were clustered together, and these results were also found in the distance index within-group analysis for bacterial and fungal communities in the T. foetida-infected and mock groups.

Identification of Tilletia foetida, Ustilago tritici, and Urocystis tritici Based on Near-Infrared Spectroscopy

Identifying plant pathogens for disease diagnosis and disease control strategy making is of great significance. In this study, based on near-infrared spectroscopy, a method for identifying three kinds of pathogens causing wheat smuts, including Tilletia foetida, Ustilago tritici, and Urocystis tritici, was investigated. Based on the acquired near-infrared spectral data of the teliospore samples of the three pathogens, pathogen identification models were built in different spectral regions using distinguished partial least squares (DPLS), backpropagation neural network (BPNN), and support vector machine (SVM). Satisfactory identification results were achieved using the DPLS, BPNN, and SVM models built in each of the 22 spectral regions. By contrast, the modeling effects of DPLS and SVM were better than those of BPNN. The modeling ratio of the training set to the testing set affected the identification results of the BPNN models more than those obtained using the DPLS and SVM models. In this study, a rapid, accurate, and nondestructive method was provided for plant pathogen identification, and some basis was provided for disease diagnosis, pathogen monitoring, and disease control. Moreover, some methodological references and supports were provided for identification of quarantine wheat smut fungi in plant quarantine.

Assessment of the reactions of pure lines selected from Turkish bread wheat landraces against bunt disease (Tilletia foetida) with the GGE-biplot method

The present research was conducted to determine the reactions of 200 pure lines selected from bread wheat landraces collected from 18 provinces and seven regions of Turkey against bunt disease (Tilletia foetida) under field conditions for 3 years. Bunt disease reactions of pure lines were assessed based on the infected spike/total spike ratio. For visually assessed materials, the GGE-biplot method, where G = genotype effect and GE = genotype-by-environment effect, was used to group the reactions against bunt disease. Fifty-nine pure lines showed high resistance (with infection rates ranging from 0.1 to 10%); 24 in the moderate resistance (with infection rates ranging from 10.1 to 25%); 75 in the moderate susceptibility (with infection rates ranging from 25.1 to 45%); 38 in the susceptibility (with infection rates ranging from 45.1 to 70%) and finally four in the highly susceptibility (with infection rates of >70.1%). PC1 and PC2 of the GGE-biplot graph created over the years explained 76.49% of the total variation. The GGE-biplot graph provided efficient identification of resistant genotypes. The lowest PC1 values and PC2 values close to 0.0 explained the resistance of pure line to bunt disease best. The resistance of pure lines to bunt disease over the biplot decreased from the first section through the last section. Based on the results of present study, 19 pure lines (located within the first circle of the biplot graph) were selected for resistance breeding programmes against the diseases.

Spindle pole body fusion in the smut fungus Tilletia foetida

Fusion of double-structured, interphase spindle pole bodies (SPBs) occurred before nuclear fusion in heterokaryotic secondary sporidia. The SPBs of two separate nuclei were juxtaposed with their long axes perpendicular to each other. Also, SPBs were observed oriented with their long axes parallel and fused to each other at both ends. Fusion apparently continued toward the midportion of the SPBs. Nuclei were observed joined together in a narrow region. These nuclei appeared to share a single SPB that was located opposite to a protuberance on both nuclei. Following fusion, the SPB apparently returned to an interphase structure.