Metabolite profiling of wheat flag leaf and grains during grain filling phase as affected by sulfur fertilisation

Increasing prices for wheat products and fertilisers call for an adjusted agricultural management to maintain yield and to improve product quality. With the increased use of sulfur-free fertilisers in modern cropping systems and the decrease of atmospheric sulfur emissions by industry, sulfur has become a major limiting factor for crop production. The presented data showed that by using GC-MS it was possible to quantitatively detect a set of 72 different metabolites including amino acids, organic acids, sugars, sugar phosphates, and sugar alcohols, phenolic compounds and nucleotides from wheat grains and flag leaves of a pot experiment. A principal component analysis (PCA) revealed a clear separation of flag leaves and grains and a clear separation of non-fertilised and fertilised flag leaves. It could further be shown by PCA, that the low level sulfur fertilisation is also separated from the higher fertilised grains. A considerable influence of the sulfur fertilisation not only on sulfur rich amino acids but also on the sugar metabolism was detected. With increasing sulfur fertilisation six sugars and sugar derivates in the grain such as glucose-6P, galactose, trehalose, cellobiose, melibiose, fumarate, glycerate and the nucleotide uracil were enhanced. Therefore, it was concluded that photosynthesis was limited in developing plants suffering from sulfur deficiency. Late sulfur fertilisation is a procedure that can help to prevent sulfur deficiency. A latent sulfur deficiency at ear emergence can be compensated by late sulfur fertilisation, as wheat plants can replenish sulfate deficits within a short time.