Oilseed rape (Brassica napus L.) was formed~7500 years ago by hybridization between B. rapa and B. oleracea, followed by chromosome doubling, a process known as allopolyploidy. Together with more ancient polyploidizations, this conferred an aggregate 72× genome multiplication since the origin of angiosperms and high gene content. We examined the B. napus genome and the consequences of its recent duplication. The constituent A n and C n subgenomes are engaged in subtle structural, functional, and epigenetic cross-talk, with abundant homeologous exchanges. Incipient gene loss and expression divergence have begun. Selection in B. napus oilseed types has accelerated the loss of glucosinolate genes, while preserving expansion of oil biosynthesis genes. These processes provide insights into allopolyploid evolution and its relationship with crop domestication and improvement.T he Brassicaceae are a large eudicot family (1) and include the model plant Arabidopsis thaliana. Brassicas have a propensity for genome duplications ( Fig. 1) and genome mergers (2). They are major contributors to the human diet and were among the earliest cultigens (3).B. napus (genome A n A n C n C n ) was formed by recent allopolyploidy between ancestors of B. oleracea (Mediterranean cabbage, genome C o C o ) and B. rapa (Asian cabbage or turnip, genome A r A r ) and is polyphyletic (2, 4), with spontaneous formation regarded by Darwin as an example of unconscious selection (5). Cultivation began in Europe during the Middle Ages and spread worldwide. Diversifying selection gave rise to oilseed rape (canola), rutabaga, fodder rape, and kale morphotypes grown for oil, fodder, and food (4, 6).The homozygous B. napus genome of European winter oilseed cultivar 'Darmor-bzh' was assembled with long-read [>700 base pairs (bp)] 454 GS-FLX+ Titanium (Roche, Basel, Switzerland) and Sanger sequence (tables S1 to S5 and figs. S1 to S3) (7). Correction and gap filling used 79 Gb of Illumina (San Diego, CA) HiSeq sequence. A final assembly of 849.7 Mb was obtained with SOAP (8) and Newbler (Roche), with 89% nongapped sequence (tables S2 and S3). Unique mapping of 5× nonassembled 454 sequences from B. rapa ('Chiifu') or B. oleracea (' TO1000') assigned most of the 20,702 B. napus scaffolds to either the A n (8294) or the C n (9984) subgenomes (tables S4 and S5 and fig. S3). The assembly covers~79% of the 1130-Mb genome and includes 95.6% of Brassica expressed sequence tags (ESTs) (7). A single-nucleotide polymorphism (SNP) map (tables S6 to S9 and figs. S4 to S8) genetically anchored 712.3 Mb (84%) of the genome assembly, yielding pseudomolecules for the 19 chromosomes (table S10).The assembled C n subgenome (525.8 Mb) is larger than the A n subgenome (314.2 Mb), consistent with the relative sizes of the assembled C o genome of B. oleracea (540 Mb, 85% of thẽ 630-Mb genome) and the A r genome of B. rapa (312 Mb, 59% of the~530-Mb genome) (9-11). The B. napus assembly contains 34.8% transposable elements (TEs), less than the 40% estimated from raw reads (table...

Analogs of the CLV3 peptide: synthesis and structure-activity relationships focused on proline residues. Plant Cell Physiol. 52, 30-36.

No abstract

The diversity of petal and leaf color can improve the ornamental value of rapeseed and promote the development of agriculture and tourism. The two copies of carotenoid isomerase gene (BnaCRTISO) in Brassica napus (BnaA09.CRTISO and BnaC08.CRTISO) was edited using the CRISPR/Cas9 system in the present study. The mutation phenotype of creamy white petals and yellowish leaves could be recovered only in targeted mutants of both BnaCRTISO functional copies, indicating that the redundant roles of BnaA09.CRTISO and BnaC08.CRTISO are vital for the regulation of petal and leaf color. The carotenoid content in the petals and leaves of the BnaCRTISO double mutant was significantly reduced. The chalcone content, a vital substance that makes up the yellow color, also decreased significantly in petals. Whereas, the contents of some carotenes (lycopene, α-carotene, γ-carotene) were increased significantly in petals. Further, transcriptome analysis showed that the targeted mutation of BnaCRTISO resulted in the significant down-regulation of important genes BnaPSY and BnaC4H in the carotenoid and flavonoid synthesis pathways, respectively; however, the expression of other genes related to carotenes and xanthophylls synthesis, such as BnaPDS3, BnaZEP, BnaBCH1 and BCH2, was up-regulated. This indicates that the molecular mechanism regulating petal color variation in B. napus is more complicated than those reported in Arabidopsis and other Brassica species. These results provide insight into the molecular mechanisms underlying flower color variation in rapeseed and provides valuable resources for rapeseed breeding.