Investigations into the Mechanisms of Resistance to Fusarium Head Blight in Wheat

Fusarium head blight (FHB), caused by the fungal pathogen Fusarium graminearum, is a devastating disease of wheat and barely. Control of FHB has proven to be especially difficult in wheat, where genetic resistance is infrequent, quantitative in nature, and often must be bred into elite lines from varieties of little commercial value. Resistance to the spread of the pathogen following infection of a single floret, known as type II resistance, is poorly understood at the molecular level and is therefore difficult to make use of in order to develop better performing varieties. The objective of this study was to gain a better understanding of the molecular mechanisms behind type II resistance to F. graminearum. In order to achieve this, a list of candidate genes with known or suspected general defense functions was compiled. These genes were targeted for silencing in a resistant variety using virus induced gene silencing (VIGS). This study demonstrates that ethylene (ET) signaling is vitally important to the type II resistance mechanism found naturally in the wheat variety Ning7840. Silencing of the ET biosynthesis gene SAMs and the transcription factor TaERF 7-1 resulted in the conversion to susceptibility in the resistant cultivar. The VIGS results were then confirmed by chemically manipulating ET signaling. Inhibition of ET signaling with the compound 1-MCP generated similar results in Ning and actually enhanced the susceptibility of the already susceptible line Bobwhite. 1-MCP treatment also rendered Ning more sensitive to deoxynivalenol, the toxin produced by F. graminearum when a single floret was exposed to the toxin alone. Augmentation of ET signaling with the immediate biological precursor 1-aminocycloproane-1-carboxylic acid (ACC), had no effect on the already resistant Ning, but significantly increased resistance in Bobwhite. ACC treatment in both varieties also caused an increase in lignin deposition. Furthermore, silencing of the genes BAK1, BRI1, CEBiP, Chorismate synthase, and Anthranilate N-benzoylransferase results in conversion of Ning to susceptibility. These genes are all linked with basal defense, and therefore, ethylene is likely modulating the resistance mechanism of wheat to F. graminearum by activating basal defense

Perspectives on ENCODE

The Encylopedia of DNA Elements (ENCODE) Project launched in 2003 with the long-term goal of developing a comprehensive map of functional elements in the human genome. These included genes, biochemical regions associated with gene regulation (for example, transcription factor binding sites, open chromatin, and histone marks) and transcript isoforms. The marks serve as sites for candidate cis-regulatory elements (cCREs) that may serve functional roles in regulating gene expression1. The project has been extended to model organisms, particularly the mouse. In the third phase of ENCODE, nearly a million and more than 300,000 cCRE annotations have been generated for human and mouse, respectively, and these have provided a valuable resource for the scientific community.11Nsciescopu

Expanded encyclopaedias of DNA elements in the human and mouse genomes

AbstractThe human and mouse genomes contain instructions that specify RNAs and proteins and govern the timing, magnitude, and cellular context of their production. To better delineate these elements, phase III of the Encyclopedia of DNA Elements (ENCODE) Project has expanded analysis of the cell and tissue repertoires of RNA transcription, chromatin structure and modification, DNA methylation, chromatin looping, and occupancy by transcription factors and RNA-binding proteins. Here we summarize these efforts, which have produced 5,992 new experimental datasets, including systematic determinations across mouse fetal development. All data are available through the ENCODE data portal (https://www.encodeproject.org), including phase II ENCODE1 and Roadmap Epigenomics2 data. We have developed a registry of 926,535 human and 339,815 mouse candidate cis-regulatory elements, covering 7.9 and 3.4% of their respective genomes, by integrating selected datatypes associated with gene regulation, and constructed a web-based server (SCREEN; http://screen.encodeproject.org) to provide flexible, user-defined access to this resource. Collectively, the ENCODE data and registry provide an expansive resource for the scientific community to build a better understanding of the organization and function of the human and mouse genomes.11Nsciescopu