Analysis of trehalose 6-phosphate metabolism in C4 plants

TONETTI, TOMÁS; LUCERO, LEANDRO E.; FEIL, REGINA; ARRIVAULT, STEPHANIE; STITT, MARK; LUNN, JOHN E.; FIGUEROA, CARLOS M.

Paraná

Congreso; LIV Reunión Anual de la SAIB; 2018

SAIB

Trehalose 6-phosphate (Tre6P) is asignal metabolite that coordinates carbon metabolism with plant growth anddevelopment. Our current understanding of Tre6P metabolism and signalling inplants is based almost entirely on studies of Arabidopsis, a C3eudicot species. The metabolism and growth of grasses that perform C4photosynthesis (such as maize, sorghum and sugarcane) are very different fromArabidopsis. The aim of this project is to understand the regulation of carbonmetabolism by Tre6P in the grass Setariaviridis, which has been widely adopted as a model for the major C4crop species. By means of phylogenetic analysis we identified 21 genes encodingTre6P-related enzymes: 10 Tre6P synthases (TPS), 10 Tre6P phosphatases (TPP)and 1 trehalase. Using publicly available RNAseq data for S. viridis we found that TPS1 (the isoform responsible for Tre6P synthesis)and two TPP isoforms are preferentially expressed in bundle sheath cells. Toinvestigate the distribution of Tre6P in S.viridis leaves, we enriched mesophyll and bundle sheath cells by sequentialsieving of finely ground leaf tissue (suspended in liquid nitrogen) through aseries of nylon meshes with different pore sizes. Interestingly, we observed anasymmetric distribution of Tre6P (71-84% in bundle sheath cells). These resultsstrongly suggest that Tre6P metabolism mainly occurs in bundle sheath cells. Weenvisage that knowledge acquired from study of S. viridis will be useful to better understand photoassimilatepartitioning and source-sink relations in the major C4 crop species.