Expression Analysis of Two Genes Coding for Trehalose-6-Phosphate Synthase (TPS), in Sugarcane (Saccharum spp.) under Water Stress

The accumulation of trehalose (α-D-glucopyranosyl-[1,1]-α-D-glucopyranoside), a sugar with osmoprotectant properties, is very common in microorganisms, invertebrates and in resurrection plants. However, in the majority of higher plants, it is found in trace amounts. Trehalose is synthesized from the UDP-glucose and glucose-6-phosphate in a two-step process with two enzymes, trehalose-6-phosphate synthase or TPS (EC 2.4.1.15 and EC 2.4.1.36) and trehalose-6-phosphate phosphatase or TPP (EC 3.1.3.12). The trehalose-6-phosphate synthase and its product of the trehalose-6-phosphate (T6P) are probable signaling molecules in the carbohydrate metabolism, contributing to enhancing the plants tolerance to water stress. Water scarcity is one of the most important factors that influence productivity in sugarcane (Saccharum spp.) and it activates a cascade of metabolic events and necessary morphologic changes for the survival of the plant under stress. Here we show the in silico expression study of TPS in different libraries from the SUCEST project. Our results showed that the TPS genes are present in all tissues and that they are divided into two subfamilies (class I and II). It is shown that STPS1 belongs to the class I, therefore, it does not have an active phosphatase (TPP) domain, whereas, the STPS2 has an active TPP domain (class II) determined by the presence of phosphatase boxes. Expression analyses based on the semi-quantitative method of the reverse transcription polymerase chain reaction (RT-PCR) show that the STPS1 gene is up-regulated in the tolerant cultivar under stress and down-regulated in susceptible plants. The STPS2 gene does not show considerable variations in the expression levels under the same treatments. The discovery of active genes such as STPS1 and STPS2 in plants under water stress, contributes for the concerning about the cascade of responses in plants under water deficit and points out to target genes for plant breeding.