Genetic sources and loci for wheat head blast resistance identified by genome-wide association analysis

The emergence and spread of wheat blast caused by fungal pathogen Magnaporthe oryzae pathotype Triticum is a threat to global wheat production.The resistance level and genetic loci for blast resistance in Chinese germplasm remain unknown.A panel of 266 bread wheat accessions from China,CIMMYTMexico and other countries was screened for head blast resistance under 12 field experiments in Bolivia and Bangladesh.Subsequently,a genome-wide association study was performed to understand the genetic basis of wheat blast resistance.The average blast index of all the accessions was 53.7%±12.7%,and 10 accessions including Chinese accessions Yumai 10 and Yu 02321 showed moderate to high levels of blast resistance,accounting for only 3.8%in the panel.Fifty-eight significant SNPs clustered in a 28.9 Mb interval on the 2 AS/2 NS translocation region,explaining phenotypic variation between10.0%and 35.0%.The frequency of the 2 AS/2 NS translocation in the Chinese accessions was as low as4.5%.These results indicated that the 2 NS fragment was the only major locus conferring resistance to wheat blast in this panel,and the resistant and moderately resistant lines identified could be deployed in breeding.

Genome-wide identification and characterization of thaumatin-like protein family genes in wheat and analysis of their responses to Fusarium head blight infection

Thaumatin-like proteins (TLPs) play potential roles in plant resistance to various diseases. Identifying TLPs is neces-sary to determine their function and apply them to plant disease resistance. However, limited information is available about TLP-family genes in wheat, especially regarding their responses to Fusarium species, which cause Fusarium head blight in wheat. In this study, we conducted a comprehensive genome-wide survey of TLP genes in wheat and identified 129 TLP genes in the wheat genome, which were unevenly distributed on 21 wheat chromosomes, with 5A containing the highest number. Phylogenetic analysis showed that these 129 wheat TLP genes together with 24 Arabidopsis TLPs were classified into 7 groups based on the protein sequences. We systematically analyzed the genes in terms of their sequence characterization, chromosomal locations, exon-intron distribution, duplication (tandem and segmental) events and expression profiles in response to Fusarium infection. Furthermore, we analyzed differen-tially expressed TLP genes based on publicly available RNA-seq data obtained from a resistant near isogenic wheat line at different time points after Fusarium graminearum inoculation. Then, the expression of 9 differentially expressed TLP genes was confirmed by real-time PCR, and these 9 genes were all upregulated in the resistant Sumai 3 variety, which was generally consistent with the RNA-seq data. Our results provide a basis for selecting candidate wheat TLP genes for further studies to determine the biological functions of the TLP genes in wheat.