Sucrose metabolism during fruit development in Coffea racemosa

Abstract

Sucrose is one of the compounds in the raw coffee bean that has been identified as an important precursor of coffee flavour and aroma. In order to increase our knowledge of sucrose metabolism in coffee species, sucrose and reducing sugar content were investigated in the fast fruit-ripening coffee species Coffea racemosa. Fruits were harvested regularly from anthesis, until the point of complete fruit maturation and tissue development, followed by measurement of fruit tissue weight. Pericarp was the most abundant tissue, and always represented around 70-80% of fruit fresh weight. The perisperm present in young fruits was rapidly replaced by the endosperm at around 40 days after flowering (DAF). In the latter tissue, total and reducing sugars decreased during development. However, sucrose content was maintained at a relatively high level throughout fruit development, with a peak at 40 DAF that coincided with the highest level of sucrose synthase (SUS) activity detected in this tissue. For all endosperm developmental stages analysed, very low invertase activity was observed, suggesting a limited role for this enzyme in sucrose metabolism. Northern blot experiments using SUS1 and SUS2 cDNA sequences from Coffea arabica as probes were carried out to study the expression of SUS-encoding genes. The SUS1 transcripts of C. racemosa overlapped with the peak of SUS activity in the endosperm, whereas SUS2 transcripts accumulated mainly during the latest stages of endosperm development. Altogether, these results suggest that the SUS1 isoform of SUS is essential for sucrose accumulation in the fruits of C. racemosa.

Effects of shade on the development and sugar metabolism of coffee (Coffea arabica L.) fruits

“…It is also worth noting that SUS mRNA and protein levels were not closely coupled, as illustrated here by the fact that the maximum SUS1 expression was detected before the peak of SUS activity, which was usually observed at 175 DAF. Such observations were previously reported for SUS during fruit development of C. racemosa [13], but also for other plants, such as tomato [44]. This could be attributed to particular regulation processes commonly reported to occur for SUS [46].…”

Some thoughts on the physiology of caffeine in coffee: and a glimpse of metabolite profiling

“…experienced by generations in the case of caffeine (Fisone et al, 2004;Cauli and Morelli, 2005). (Rogers et al, 1999;Geromel et al, 2004;Melo and Mazzafera, 2004) regarding the perisperm-endosperm transition (see below) are very promising. Since, as outlined before, caffeine and its allies are by far the best investigated compounds in coffee, I will take them as an example to illustrate in the following their physiology through the coffee plant life, from germination via leaf formation and branching to flowering and seed production.…”

“…Seemingly, the mother avoids the 'parental conflict' (Barton et al, 1984;Haig and Westoby, 1989) by establishing a placeholder, the 'perisperm bean', and by this acts like a handicapper decreeing several parameters: The size of the cavity for the latter endosperm bean, the amount of phosphate to be used (West et al, 1995), the velocity of embryo differentiation (Borisjuk et al, 2004), i.e. the pathways of sugar-signaling by a specific sugar pattern (Rogers et al, 1999;Geromel et al, 2004), the amount of carbon (energy) sources for development and last but not least, the extent of chemical defence by allocation of secondary compounds or their precursors such as e.g. quinic acid (Rogers et al, 1999).…”

Extracción, purificación y transformación enzimática del ácido clorogénico da la pulpa de café

“…Los frutos más pequeños corresponden a las cerezas de la variedad Bourbon. Varios autores han descrito los cambios en el tamaño y el peso de los frutos del café durante la maduración (Geromel et al, 2004;Koshiro et al, 2007;Carvajal-Herrera et al, 2012). Las diferencias físicas (peso y volumen) entre los frutos de café de diferentes variedades son conocidas por los agricultores, pero no han sido descritas en la bibliografía.…”