Trehalose-6-phosphate synthase 1 is not the only active TPS in Arabidopsis thaliana

Abstract

Trehalose metabolism is essential for normal growth and development in higher plants. It is synthesized in a two-step pathway catalyzed by trehalose-6-phosphate (Tre6P) synthase (TPS) and trehalose phosphatase. Arabidopsis thaliana has 11 TPS or TPS-like proteins, which belong to two distinct clades: class I (AtTPS1-AtTPS4) and class II (AtTPS5-AtTPS11). Only AtTPS1 has previously been shown to have TPS activity. Null A. thaliana tps1 mutants fail to complete embryogenesis and rescued lines have stunted growth and delayed flowering, indicating that AtTPS1 is important throughout the life cycle. Here we show that expression of AtTPS2 or AtTPS4 enables the yeast tps1-delta tps2-delta mutant to grow on glucose and accumulate Tre6P and trehalose. Class II TPS genes did not complement the yeast mutant. Thus, A. thaliana has at least three catalytically active TPS isoforms, suggesting that loss of Tre6P production might not be the only reason for the growth defects of A. thaliana tps1 mutants.