title: Biochemical and genomic analysis of sucrose metabolism during coffee (Coffea arabica) fruit development.
abstract: Sucrose metabolism and the role of sucrose synthase were investigated in the fruit tissues (pericarp, perisperm, and endosperm) of Coffea arabica during development. Acid invertase, sucrose phosphate synthase, and sucrose synthase activities were monitored and compared with the levels of sucrose and reducing sugars. Among these enzymes, sucrose synthase showed the highest activities during the last stage of endosperm and pericarp development and this activity paralleled closely the accumulation of sucrose in these tissues at this stage. Carbon partitioning in fruits was studied by pulse-chase experiments with (14)C-sugars and revealed high rates of sucrose turnover in perisperm and endosperm tissues. Additional feeding experiments with (14)CO(2) showed that leaf photosynthesis contributed more to seed development than the pericarp in terms of photosynthate supply to the endosperm. Sugar analysis, feeding experiments, and histological studies indicated that the perisperm plays an important role in this downloading process. It was observed that the perisperm presents a transient accumulation of starch which is degraded as the seed develops. Two full-length cDNAs (CaSUS1 and CaSUS2) and the complete gene sequence of the latter were also isolated. They encode sucrose synthase isoforms that are phylogenetically distinct, indicating their involvement in different physiological functions during cherry development. Contrasting expression patterns were observed for CaSUS1 and CaSUS2 in perisperm, endosperm, and pericarp tissues: CaSUS1 mRNAs accumulated mainly during the early development of perisperm and endosperm, as well as during pericarp growing phases, whereas those of CaSUS2 paralleled sucrose synthase activity in the last weeks of pericarp and endosperm development. Taken together, these results indicate that sucrose synthase plays an important role in sugar metabolism during sucrose accumulation in the coffee fruit.
authors.affiliation: UNICAMP (Universidade Estadual de Campinas), Departamento de Fisiologia Vegetal, IB, CP 6109, 13083-970 Campinas, SP, Brazil.
authors.forename: Clara
authors.initials: C
authors.lastname: Geromel
authors.forename: Lúcia Pires
authors.initials: LP
authors.lastname: Ferreira
authors.forename: Sandra Maria Carmelo
authors.initials: SM
authors.lastname: Guerreiro
authors.forename: Aline Andréia
authors.initials: AA
authors.lastname: Cavalari
authors.forename: David
authors.initials: D
authors.lastname: Pot
authors.forename: Luiz Filipe Protásio
authors.initials: LF
authors.lastname: Pereira
authors.forename: Thierry
authors.initials: T
authors.lastname: Leroy
authors.forename: Luiz Gonzaga Esteves
authors.initials: LG
authors.lastname: Vieira
authors.forename: Paulo
authors.initials: P
authors.lastname: Mazzafera
authors.forename: Pierre
authors.initials: P
authors.lastname: Marraccini
mesh_terms: D001692:Biological Transport; D015139:Blotting, Southern; D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D002250:Carbon Radioisotopes; D040503:Coffea / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D005632:Fructose / Q000378:metabolism; D005638:Fruit / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D018745:Genome, Plant; D023281:Genomics; D005964:Glucosyltransferases / Q000145:classification / Q000378:metabolism / Q000502:physiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism*; D043324:beta-Fructofuranosidase / Q000378:metabolism
chemical_list: D002250:Carbon Radioisotopes; D010940:Plant Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D002245:Carbon Dioxide; D005632:Fructose; D013395:Sucrose; D002244:Carbon; D005964:Glucosyltransferases; C022699:sucrose synthase; C022698:sucrose-phosphate synthase; D043324:beta-Fructofuranosidase