An annotated reference sequence representing the hexaploid bread wheat genome in 21 pseudomolecules has been analyzed to identify the distribution and genomic context of coding and noncoding elements across the A, B, and D subgenomes. With an estimated coverage of 94% of the genome and containing 107,891 high-confidence gene models, this assembly enabled the discovery of tissue- and developmental stage–related coexpression networks by providing a transcriptome atlas representing major stages of wheat development. Dynamics of complex gene families involved in environmental adaptation and end-use quality were revealed at subgenome resolution and contextualized to known agronomic single-gene or quantitative trait loci. This community resource establishes the foundation for accelerating wheat research and application through improved understanding of wheat biology and genomics-assisted breeding.
Virus‐induced gene silencing was used to assess the function of random Nicotiana benthamiana cDNAs in disease resistance. Out of 4992 cDNAs tested from a normalized library, there were 79 that suppressed a hypersensitive response (HR) associated with Pto‐mediated resistance against Pseudomonas syringae. However, only six of these clones blocked the Pto‐mediated suppression of P.syringae growth. The three clones giving the strongest loss of Pto resistance had inserts corresponding to HSP90 and also caused loss of Rx‐mediated resistance against potato virus X and N‐mediated tobacco mosaic virus resistance. The role of HSP90 as a cofactor of disease resistance is associated with stabilization of Rx protein levels and could be accounted for in part by SGT1 and other cofactors of disease resistance acting as co‐chaperones. This approach illustrates the potential benefits and limitations of RNA silencing in forward screens of gene function in plants.
Roses hold high cultural and economic importance as ornamentals and for the perfume industry. We report the rose whole genome sequencing and assembly and resequencing of major genotypes that contributed to rose domestication. We generated a homozygous genotype from a heterozygous diploid modern roses progenitor, Rosa chinensis ‘Old Blush’. Using Single Molecule Real-Time sequencing and a meta-assembly approach we obtained one of the most complete plant genomes to date. Diversity analyses highlighted the mosaic origin of ‘La France’, one of the first hybrids combining the growth vigor of European species and recurrent blooming of Chinese species. Genomic segments of Chinese ancestry revealed new candidate genes for recurrent blooming. Reconstructing regulatory and secondary metabolism pathways allowed us to propose a model of interconnected regulation of scent and flower color. This genome provides a foundation for understanding the mechanisms governing rose traits and will accelerate improvement in roses, Rosaceae and ornamentals.
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