Silencing of the tomato Sugar Partitioning Affecting protein (SPA) modifies sink strength through a shift in leaf sugar metabolism |
| |
Authors: | Luisa Bermúdez Fabiana de Godoy Pierre Baldet Diego Demarco Sonia Osorio Leandro Quadrana Juliana Almeida Ramón Asis Yves Gibon Alisdair R. Fernie Magdalena Rossi Fernando Carrari |
| |
Affiliation: | 1. Departamento de Botanica, Instituto de Biociências, Universidade de S?o Paulo, Rua do Mat?o, , S?o Paulo, 05508‐900 SP, Brazil;2. Instituto de Biotecnología, Instituto Nacional de Tecnología Agropecuaria (IB‐INTA), , Castelar, B1712WAA Argentina;3. INRA‐Bordeaux, Fruit Biology and Pathology Unit, , Villenave d'Ornon, F‐33883 France;4. Max Planck Institute of Molecular Plant Physiology, Wissenschaftspark Golm, , Potsdam‐G?lm, D‐14476 Germany;5. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), , Castelar, B1712WAA Argentina;6. CIBICI, Facultad de Ciencias Químicas Universidad Nacional de Córdoba, , Córdoba, CC 5000 Argentina |
| |
Abstract: | Limitations in our understanding about the mechanisms that underlie source‐sink assimilate partitioning are increasingly becoming a major hurdle for crop yield enhancement via metabolic engineering. By means of a comprehensive approach, this work reports the functional characterization of a DnaJ chaperone related‐protein (named as SPA; sugar partition‐affecting) that is involved in assimilate partitioning in tomato plants. SPA protein was found to be targeted to the chloroplast thylakoid membranes. SPA‐RNAi tomato plants produced more and heavier fruits compared with controls, thus resulting in a considerable increment in harvest index. The transgenic plants also displayed increased pigment levels and reduced sucrose, glucose and fructose contents in leaves. Detailed metabolic and enzymatic activities analyses showed that sugar phosphate intermediates were increased while the activity of phosphoglucomutase, sugar kinases and invertases was reduced in the photosynthetic organs of the silenced plants. These changes would be anticipated to promote carbon export from foliar tissues. The combined results suggested that the tomato SPA protein plays an important role in plastid metabolism and mediates the source‐sink relationships by affecting the rate of carbon translocation to fruits. |
| |
Keywords: | tomato small plastidial protein fruit metabolism source‐sink partitioning chloroplast metabolism |
|
|