Aegilops tauschii, the diploid wild progenitor of the D subgenome of bread wheat, is a reservoir of genetic diversity for improving bread wheat performance and environmental resilience. Here we sequenced 242 Ae. tauschii accessions and compared them to the wheat D subgenome to characterize genomic diversity. We found that a rare lineage of Ae. tauschii geographically restricted to present-day Georgia contributed to the wheat D subgenome in the independent hybridizations that gave rise to modern bread wheat. Through k-mer-based association mapping, we identified discrete genomic regions with candidate genes for disease and pest resistance and demonstrated their functional transfer into wheat by transgenesis and wide crossing, including the generation of a library of hexaploids incorporating diverse Ae. tauschii genomes. Exploiting the genomic diversity of the Ae. tauschii ancestral diploid genome permits rapid trait discovery and functional genetic validation in a hexaploid background amenable to breeding.

No abstract

Flavonoids represent a diversified family of phenylpropanoid-derived plant secondary metabolites.They are widely found in fruits, vegetables and medicinal herbs and plants. There has been increasing interest on flavonoids because of their proven bioactivity associated with anti-obesity, anti-cancer, anti-inflammatory, anti-diabetic activity and the prevention of aging-related chronic conditions, such as nervous and cardiovascular disease. Low bioavailability of flavonoids is a major challenge restricting their wide applications. Due to safety and economic issues, traditional plant extraction or chemical synthesis could not provide a scalable route for large-scale production of flavonoids. Alternatively, reconstruction of biosynthetic gene clusters in plants and industrially relevant microbes offer significant promise for discovery and scalable synthesis of flavonoids.This review provides an update on biotechnological production of flavonoids. We summarized the recent advances on plant metabolic engineering, microbial host and genetically encoded biosensors. Plant metabolic engineering holds the promise to improve the yield of specific flavonoids and expand the chemical space of novel flavonoids. The choice of microbial host provides the cellular chassis that could be tailored for various stereo-or regio-selective chemistries that are crucial for their bioactivities. When coupled with transcriptional biosensing, genetically encoded biosensors could be welded into cellular metabolism to achieve high throughput screening or dynamic carbon flux re-allocation to deliver efficient and robust microbial workhorse. The convergence of these technologies will translate the vast majority of plant genetic resources into valuable flavonoids with pharmaceutical/nutraceutical values in the foreseeable future.

No abstract

Wild relatives of wheat serve as an extraordinary source of variability for breeding programs due to their capabilities to respond to various environmental stresses. Here, we investigated some species possessing a D genome (T. aestivum, Ae. tauschii, Ae. crassa and Ae. cylindrica) in terms of relative water content (RWC), stomatal conductance (Gs), relative chlorophyll content, initial fluorescence (Fo), maximum quantum yield of PSII (Fv/Fm), maximum primary yield of PSII photochemistry (Fv/Fo), as well as shoot fresh and dry biomasses under control and water deficit conditions. Our results revealed that water deficit negatively affected all traits; shoot fresh weight, Gs and RWC showed the highest reduction compared to the control condition. Principal component analysis (PCA) identified two PCs that accounted for 53.36% of the total variation in the water deficit conditions. Correlation analysis and PCA-based biplots showed that stress tolerance index (STI) is significantly associated with Fv/Fm and Fv/Fo under water stress conditions, suggesting that these are the best parameters to evaluate when screening for tolerant samples at the seedling stage. We identified 19 accessions from Ae. crassa and one from Ae. tauschii as the most tolerant samples. In conclusion, Ae. crassa might provide an ideal genetic resource for drought-tolerant wheat breeds.