Modulation of organic acids and sugar content in tomato fruits by an abscisic acid-regulated transcription factor.
Growing evidence suggests that the phytohormone abscisic acid (ABA) plays a role in fruit development. ABA signaling components of developmental programs and responses to stress conditions include the group of basic leucine zipper transcriptional activators known as ABA-response element binding factors (AREBs/ABFs). AREB transcription factors mediate ABA-regulated gene expression involved in desiccation tolerance and are expressed mainly in seeds and in vegetative tissues under stress; however, they are also expressed in some fruits such as tomato. In order to get an insight into the role of ABA signaling in fruit development, the expression of two AREB-like factors were investigated during different developmental stages. In addition, tomato transgenic lines that overexpress and downregulate one AREB-like transcription factor, SlAREB1, were used to determine its effect on the levels of some metabolites determining fruit quality. Higher levels of citric acid, malic acid, glutamic acid, glucose and fructose were observed in SlAREB1-overexpressing lines compared with those in antisense suppression lines in red mature fruit pericarp. The higher hexose concentration correlated with increased expression of genes encoding a vacuolar invertase (EC 3.2.1.26) and a sucrose synthase (EC 2.4.1.13). No significant changes were found in ethylene content which agrees with the normal ripening phenotype observed in transgenic fruits. These results suggest that an AREB-mediated ABA signal affects the metabolism of these compounds during the fruit developmental program.
Instituto de Biología Vegetal y Biotecnología, Universidad de Talca, Talca, Chile.
Adriana
A
Bastías
María
M
López-Climent
Mercedes
M
Valcárcel
Salvador
S
Rosello
Aurelio
A
Gómez-Cadenas
José A
JA
Casaretto
D000040:Abscisic Acid / Q000378:metabolism*; D000143:Acids / Q000032:analysis; D005030:Ethylenes / Q000032:analysis; D005638:Fruit / Q000737:chemistry* / Q000254:growth & development; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D018525:Germination; D006601:Hexoses / Q000032:analysis*; D018551:Solanum lycopersicum / Q000235:genetics* / Q000502:physiology; D010937:Plant Growth Regulators / Q000378:metabolism; D010940:Plant Proteins / Q000502:physiology; D030821:Plants, Genetically Modified / Q000235:genetics / Q000502:physiology; D012639:Seeds / Q000737:chemistry / Q000254:growth & development; D014157:Transcription Factors / Q000502:physiology*
D000143:Acids; D005030:Ethylenes; D006601:Hexoses; D010937:Plant Growth Regulators; D010940:Plant Proteins; D014157:Transcription Factors; D000040:Abscisic Acid; C036216:ethylene