richardii do not contain caffeine (Campa et al., 2005).Ĭaffeine biosynthesis involves several adenine-methylation steps, of which the major intermediates are methylxanthosine and theobromine. eugenioides 0.3-0.8% (Mazzafera et al., 1997), whereas the beans of C. The caffeine content of coffee beans (expressed as the percentage dry weight) varies among Coffea species: C. Of the compounds present in coffee beans, caffeine is one of the best known and studied because of its physiological effects on humans and its role in the physiology and life cycle of coffee plants. Several studies have shown that coffee species and cultivars vary in their sugar, phenolic compound, lipid and total soluble solid content (Mazzafera et al., 1998 Bradbury, 2001 Aguiar et al., 2005). The influence of genetic background on final cup quality is related mainly to the biochemical composition of the fruits and beans. arabica, including genetic background, environmental conditions, cultivation methods and post-harvest processing.
Several parameters are associated with the high cup quality of C. eugenioides (Lashermes et al., 1999), is the most important species cultivated for coffee production, primarily because of the excellent beverage quality provided by its beans. Key words: coffee, cup quality, differential expression, naturally decaffeinated.Ĭoffea arabica, an autogamous, allotetraploid (2n = 4x = 44 chromosomes) species that probably resulted from the natural hybridization of two diploid species, C. These findings indicate that the absence of caffeine in these mutants probably resulted from a combination of transcriptional regulation and the presence of mutations in the caffeine synthase amino acid sequence. The sequence of the mutant caffeine synthase gene revealed the substitution of isoleucine for valine in the enzyme active site that probably interfered with enzymatic activity. This extra transcript contained only part of exon 1 and all of exon 3. The amplification of gene-specific transcripts during fruit development revealed that low-caffeine fruits had a lower expression of the theobromine synthase and caffeine synthase genes and also contained an extra transcript of the caffeine synthase gene. IIInstituto Agronômico, Centro de Café "Alcides Carvalho", Campinas, SP, Brazilġ3001-970 Campinas, SP, this work, we studied the biosynthesis of caffeine by examining the expression of genes involved in this biosynthetic pathway in coffee fruits containing normal or low levels of this substance. Mirian Perez Maluf I, II Carla Cristina da Silva II Michelle de Paula Abreu de Oliveira II Aline Gomes Tavares II Maria Bernadete Silvarolla II Oliveiro Guerreiro Filho II Altered expression of the caffeine synthase gene in a naturally caffeine-free mutant of Coffea arabica
0 kommentar(er)
