Analysis of trehalose 6-phosphate metabolism in C4 plants

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

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 signaling inplants is based almost entirely on studies of Arabidopsis, a C3 eudicotspecies. The metabolism and growth of grasses that perform C4 photosynthesis(such as maize, sorghum and sugarcane) are very different from Arabidopsis.The aim of this project is to understand the regulation of carbon metabolism byTre6P in the grass Setariaviridis, which has been widely adopted as amodel for the major C4 crop species. By means of phylogenetic analysis weidentified 21 genes encoding Tre6P-related enzymes: 10 Tre6P synthases (TPS),10 Tre6P phosphatases (TPP) and 1 trehalase. Using publicly available RNAseqdata for S. viridis we found that TPS1 (the isoform responsible forTre6P synthesis) and two TPP isoforms are preferentially expressed in bundlesheath cells. To investigate the distribution of Tre6P in S. viridis leaves,we enriched mesophyll and bundle sheath cells by sequential sieving of finelyground leaf tissue (suspended in liquid nitrogen) through a series of nylonmeshes with different pore sizes. Interestingly, we observed an asymmetricdistribution of Tre6P (71-84% in bundle sheath cells). These results stronglysuggest that Tre6P metabolism mainly occurs in bundle sheath cells. We envisagethat knowledge acquired from study of S. viridis will be useful tobetter understand photoassimilate partitioning and source-sink relations in themajor C4 crop species.