The role of trehalose-6-phosphate (Tre6P) in starch degradation

DOS ANJOS, L; FIGUEROA, CM; FEIL, R; PANDEY, PK; STITT, M; LUNN, JE

Munich

Congreso; Botanikertagung 2015 "From molecules to the field"; 2015

German Botanical Society

Arabidopsis plants with an induced increase in Tre6P levels do not break down all of their transitory starch reserves during the night. To investigate how Tre6P influences starch content, we compared starch degradation rates in wild-type plants and in the sweet11;12 mutant, which has high levels of sucrose and Tre6P throughout the diurnal cycle. When plants were grown with a 12-h photoperiod (160 μmol m-2 s-1), starch was higher throughout the diurnal cycle in the sweet11;12 mutant than in wild-type, but the rate of starch degradation was the same in both genotypes. When plants were shifted to either high-light (320 μmol m-2 s-1; 12h:12h) or long-day (160 μmol m-2 s-1; 15h:9h) conditions for 24 h, to increase starch content at the end of the day, wild-type plants had higher rates of starch degradation. In contrast, the sweet11;12 plants had the same starch degradation rate as the control plants (12 h/12 h; 160 μmol m-2 s-1) and a marked starch excess at the end of the night. We discuss whether Tre6P regulates the rate of starch degradation per se or if it might act in a different way, e.g. by setting a basal level of starch that is not turned over on a daily basis.