Host Specificity of Soilborne Pathogens in Hordeum Species and Their Relatives.

Soilborne pathogens destabilize the yields of Triticeae crops, including barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.). Although genetic resistance derived from relatives of these species has been utilized to prevent rust diseases (i.e., in the wheat-rye 1BL-1RS translocation line), research on resistance against soilborne pathogens remains limited. Here, we performed field trials using 76 genotypes representing 28 Hordeum, six Triticum, and two Aegilops species to examine resistance against three soilborne bymoviruses: barley yellow mosaic virus (BaYMV), barley mild mosaic virus (BaMMV), and wheat yellow mosaic virus (WYMV). We also performed greenhouse tests using the soilborne fungal pathogen Fusarium pseudograminearum, which causes Fusarium crown rot (FCR). Using RT-PCR, we detected BaMMV and BaYMV in several Hordeum species, whereas WYMV induced systemic infection in the Triticum and Aegilops species. The identification of FCR susceptibility in all species examined suggests that F. pseudograminearum is a facultative fungal pathogen in Triticeae. Intraspecies variation in FCR disease severity was observed for several species, pointing to the possibility of exploring host resistance mechanisms. Therefore, by unlocking the host specificity of four soilborne pathogens in Hordeum species and their relatives, we obtained insights for the further exploration of wild sources of soilborne pathogen resistance for future wheat and barley improvement programs.

[Fast discrimination of varieties of transgene wheat based on biomimetic pattern recognition and near infrared spectra].

A new method for the fast discrimination of varieties of transgene wheat by means of near infrared spectroscopy and biomimetic pattern recognition (BPR) was proposed and the recognition models of seven varieties of transgene wheat and two varieties of acceptor wheat were built. The experiment adopted 225 samples, which were acquired from nine varieties of wheat. Firstly, a field spectroradiometer was used for collecting spectra in the wave number range from 4 000 to 12 000 cm(-1). Secondly, the original spectral data were pretreated in order to eliminate noise and improve the efficiency of models. Thirdly, principal component analysis (PCA) was used to compress spectral data into several variables, and the cumulate reliabilities of the first ten components were more than 97.28%. Finally, the recognition models were established based on BPR For the every 25 samples in each variety, 15 samples were randomly selected as the training set. The remaining 10 samples of the same variety were used as the first testing set, and all the 200 samples of the other varieties were used as the second testing set. As the 96.7% samples in the second set were correctly rejected, the average correct recognition rate of first testing set was 94.3%. The experimental results demonstrated that the recognition models were effective and efficient. In short, it is feasible to discriminate varieties of transgene wheat based on near infrared spectroscopy and BPR.

Mapping a resistance gene in wheat cultivar Yangfu 9311 to yellow mosaic virus, using microsatellite markers.

Wheat yellow mosaic disease, which is caused by wheat yellow mosaic bymovirus (WYMV) and transmitted by soil-borne fungus, results in severe damage on wheat (Triticum aestivum L.) production in China. For development of resistant cultivars to reduce wheat yield losses due to wheat yellow mosaic disease, resistance test and genetic analysis indicated that a single dominant gene in wheat cultivar Yangfu 9311 contributed to the resistance. Bulk segregant analysis was used to identify microsatellite markers linked to the resistance gene in an F(2) population derived from the cross Yangfu 9311 (resistant) x Yangmai 10 (susceptible). Microsatellite markers Xwmc41, Xwmc181, Xpsp3039, and Xgwm349 were co-dominantly or dominantly linked with the gene responsible for WYMV resistance at a distance of 8.1-11.6 cM. Based on the wheat microsatellite consensus map and the results from amplification of the cultivar Chinese Spring nulli-tetrasomic stocks, the resistance gene to wheat yellow mosaic disease derived from Yangfu 9311, temporarily named as YmYF, was thus mapped on the long arm of chromosome 2D (2DL).