Insights in Arabidopsis thaliana invertase activity regulation related to the production of root biomass

COLUCCIO LESKOW, C.; KAMENETZKY, L.; DOMÍNGUEZ, G.; CARRARI, F.

Congreso; XXVIII Reunión Argentina de Fisiología Vegetal; 2010

Improving crop yield is a major goal in plant sciences. In higher plants, carbon is transported from source to sink organs mainly in the form of sucrose, where it is hydrolyzed by invertases and sucrose synthases. By QTL mapping has recently been shown that a vacuolar invertase (vac-Inv) plays a key role in sink organs, particularly determining the root length in Arabidopsis. In this model, variation in vac-Inv activity was detected in a recombinant inbred lines population derived from a cross between two divergent accessions, Ler and CVI. This analysis revealed that the CVI allele conferred both higher Inv activity and longer roots. The main aim of this work is to understand the structural and functional differences of vac-Inv from both accessions. By DNA sequence analyses we found several polymorphisms between the CVI and Ler alleles at different coding positions leading changes in the protein sequence. Moreover, relative transcript abundance analyzed by qRT-PCR showed similar expression patterns evaluated in different organs and developmental stages of the plant. In contrast, activity assays performed in seedling stage showed differential Inv activity between Ler and CVI aloenzymes. In parallel, a detailed phenotypic evaluation of the recombinant lines was performed and suggest differences in aerial biomass that could be related to differences in root growth. In order to assess the specific activity of the different vac-Inv alleles, the coding region of each allele was cloned in an heterologous system (Pichia pastoris expression vector). Immunoblot and in vivo enzymatic activity assays , demonstrate higher expression and activity of vac-InvCVI protein.