Coffee is a valuable beverage crop due to its characteristic flavor, aroma, and the stimulating effects of caffeine. We generated a high-quality draft genome of the species Coffea canephora, which displays a conserved chromosomal gene order among asterid angiosperms. Although it shows no sign of the whole-genome triplication identified in Solanaceae species such as tomato, the genome includes several species-specific gene family expansions, among them N-methyltransferases (NMTs) involved in caffeine production, defense-related genes, and alkaloid and flavonoid enzymes involved in secondary compound synthesis. Comparative analyses of caffeine NMTs demonstrate that these genes expanded through sequential tandem duplications independently of genes from cacao and tea, suggesting that caffeine in eudicots is of polyphyletic origin. (Résumé d'auteur
Modern sugarcanes are polyploid interspecific hybrids, combining high sugar content from Saccharum officinarum with hardiness, disease resistance and ratooning of Saccharum spontaneum. Sequencing of a haploid S. spontaneum, AP85-441, facilitated the assembly of 32 pseudo-chromosomes comprising 8 homologous groups of 4 members each, bearing 35,525 genes with alleles defined. The reduction of basic chromosome number from 10 to 8 in S. spontaneum was caused by fissions of 2 ancestral chromosomes followed by translocations to 4 chromosomes. Surprisingly, 80% of nucleotide binding site-encoding genes associated with disease resistance are located in 4 rearranged chromosomes and 51% of those in rearranged regions. Resequencing of 64 S. spontaneum genomes identified balancing selection in rearranged regions, maintaining their diversity. Introgressed S. spontaneum chromosomes in modern sugarcanes are randomly distributed in AP85-441 genome, indicating random recombination among homologs in different S. spontaneum accessions. The allele-defined Saccharum genome offers new knowledge and resources to accelerate sugarcane improvement.
Caffeoyl-, feruloyl-and dicaffeoylquinic acids (chlorogenic acids) in infusions from green and medium roasted coffee beans were identified and quantified by reverse phase HPLC with photodiode array and MS 3 detection prior to assessment of the antioxidant activity using an HPLC system with post-column on-line antioxidant detection based on 2,2'-azinobis-3-ethylbenzothiazoline-6-sulphonic acid radical scavenging activity. Caffeoylquinic acids were the most abundant antioxidants and roasting induced isomerisation with a decline in 5-O-caffeoylquinic acid and concomitant increases in the 3-and 4-Oderivatives. This did not affect the level of caffeoylquinic acid-derived antioxidant activity in the roasted coffee. Roasting did, however, result in the appearance of additional unidentified HPLC peaks with antioxidant activity. Because of this and an increase in the antioxidant activity of components that did not elute from the reversed phase HPLC column, the antioxidant capacity of the beverage derived from medium roast beans was double that of the unroasted coffee. The antioxidant activity of coffees that have undergone different degrees of roasting would, therefore, appear to be due to combinations of different components. The effect of roasting on chlorogenic acids in coffee beans is considered, and the possible contribution of Maillard reaction products to the antioxidant capacity of roasted coffees is discussed. Key words: Coffea, ABTS + , chlorogenic acids, hydroxycinnamates, HPLC-MS n .Análise por HPLC "on-line" da atividade antioxidante de compostos fenólicos em café preparado por infusão e filtrado em papel: Ácidos cafeoil-, feruloil-e dicafeoilquínicos (ácidos clorogênicos) em infusões de sementes de café verde e sementes medianamente torradas foram identificados e quantificados por cromatografia líquida de alta eficiência (HPLC) em fase reversa com detecção em fotodiodo e MS 3 , antes da avaliação da atividade antioxidante usando um sistema HPLC com detecção antioxidante "on-line", baseada na eliminação de radicais pelo ácido 2,2'-azinobis-3-etilbenzotiazolina-6-sulfônico. Ácidos cafeoilquínicos foram os mais abundantes antioxidantes e a torração induziu a isomerização, com declínio do ácido 5-O-cafoilquínico e concomitante aumento dos derivados 3-e 4-O-cafeoilquínicos. Isto não afetou o nível da atividade antioxidante derivada de ácidos cafeoilquínicos no café torrado. Torração, no entanto, resultou no aparecimento de picos adicionais nas corridas cromatográficas, com atividade antioxidante. Por causa disto e de um aumento na atividade antioxidante dos componentes que não eluíram da coluna cromatográfica de fase reversa da HPLC, a capacidade antioxidante da bebida preparada de grãos de café medianamente torrados foi o dobro daquela de grãos não torrados, verdes. Portanto, a atividade antioxidante de cafés que tenham sofrido diferentes graus de torração parece ser devido a combinações de diferentes componentes. O efeito da torração sobre os ácidos clorogênicos nas sementes de café é discutido, assim como as ...
). † These authors contributed equally to this work. SUMMARYArabica coffee (Coffea arabica L.) is a self-compatible perennial allotetraploid species (2n = 4x = 44), whereas Robusta coffee (C. canephora L.) is a self-incompatible perennial diploid species (2n = 2x = 22).) is derived from a spontaneous hybridization between two closely related diploid coffee species, C. canephora (CC) and C. eugenioides (EE). To investigate the patterns and degree of DNA sequence divergence between the Arabica and Robusta coffee genomes, we identified orthologous bacterial artificial chromosomes (BACs) from C. arabica and C. canephora, and compared their sequences to trace their evolutionary history. Although a high level of sequence similarity was found between BACs from C. arabica and C. canephora, numerous chromosomal rearrangements were detected, including inversions, deletions and insertions. DNA sequence identity between C. arabica and C. canephora orthologous BACs ranged from 93.4% (between E a and C a ) to 94.6% (between C a and C). Analysis of eight orthologous gene pairs resulted in estimated ages of divergence between 0.046 and 0.665 million years, indicating a recent origin of the allotetraploid species C. arabica. Analysis of transposable elements revealed differential insertion events that contributed to the size increase in the C a sub-genome compared to its diploid relative. In particular, we showed that insertion of a Ty1-copia LTR retrotransposon occurred specifically in C. arabica, probably shortly after allopolyploid formation. The two sub-genomes of C. arabica, C a and E a , showed sufficient sequence differences, and a whole-genome shotgun approach could be suitable for sequencing the allotetraploid genome of C. arabica.
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