title: Effects of shade on the development and sugar metabolism of coffee (Coffea arabica L.) fruits.
abstract: Coffee fruits grown in shade are characterized by larger bean size than those grown under full-sun conditions. The present study assessed the effects of shade on bean characteristics and sugar metabolism by analyzing tissue development, sugar contents, activities of sucrose metabolizing enzymes and expression of sucrose synthase-encoding genes in fruits of coffee (Coffea arabica L.) plants submitted to full-sun (FS) and shade (SH) conditions. Evolution of tissue fresh weights measured in fruits collected regularly from flowering to maturation indicated that this increase is due to greater development of the perisperm tissue in the shade. The effects of light regime on sucrose and reducing sugar (glucose and fructose) contents were studied in fresh and dry coffee beans. Shade led to a significant reduction in sucrose content and to an increase in reducing sugars. In pericarp and perisperm tissues, higher activities of sucrose synthase (EC 2.4.1.13) and sucrose-phosphate synthase (SPS: EC 2.4.1.14) were detected at maturation in the shade compared with full sun. These two enzymes also had higher peaks of activities in developing endosperm under shade than in full sun. It was also noted that shade modified the expression of SUS-encoding genes in coffee beans; CaSUS2 gene transcripts levels were higher in SH than in FS. As no sucrose increase accompanied these changes, this suggests that sucrose metabolism was redirected to other metabolic pathways that need to be identified.
authors.affiliation: Departamento de Fisiologia Vegetal-IB, UNICAMP, 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: Fabrice
authors.initials: F
authors.lastname: Davrieux
authors.forename: Bernard
authors.initials: B
authors.lastname: Guyot
authors.forename: Fabienne
authors.initials: F
authors.lastname: Ribeyre
authors.forename: Maria
authors.initials: M
authors.lastname: Brígida dos Santos Scholz
authors.forename: Luiz Filipe
authors.initials: LF
authors.lastname: Protasio Pereira
authors.forename: Philippe
authors.initials: P
authors.lastname: Vaast
authors.forename: David
authors.initials: D
authors.lastname: Pot
authors.forename: Thierry
authors.initials: T
authors.lastname: Leroy
authors.forename: Armando
authors.initials: A
authors.lastname: Androcioli Filho
authors.forename: Luiz Gonzaga
authors.initials: LG
authors.lastname: Esteves Vieira
authors.forename: Paulo
authors.initials: P
authors.lastname: Mazzafera
authors.forename: Pierre
authors.initials: P
authors.lastname: Marraccini
mesh_terms: D015152:Blotting, Northern; D050260:Carbohydrate Metabolism / Q000528:radiation effects; D040503:Coffea / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D005638:Fruit / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism; D008027:Light
chemical_list: D005964:Glucosyltransferases; C022699:sucrose synthase