Identification, characterisation, and expression profile analysis of the sucrose phosphate synthase gene family in pineapple (Ananas comosus)

Sucrose plays a crucial role in plant growth and development. Sucrose phosphate synthase (SPS, EC 2.4.1.14) is a key rate-limiting enzyme in the sucrose metabolism of plants. To date, the genome-wide identification, characterisation, and expression profile analysis of SPS gene families have been reported in many species but not in pineapple (Ananas comosus). In this study, five SPS genes (AcSPS1-5), which contained sucrose synthase, glucosyltransferase, and SPP-like conserved domains, were identified. The phylogenetic tree indicated that these AcSPS genes were divided into three clades, i.e. A, B, and C. The spatiotemporal expression pattern of AcSPS gene families were first examined in pineapple. Among all tissues, AcSPS2 had the highest expression in flesh. Meanwhile, AcSPS2 expression was significantly upregulated during fruit development. Furthermore, AcSPS2 expression, SPS activity, and sucrose content consistently increased with fruit development. These results may indicate that AcSPS2 played a major role in sucrose metabolism during fruit development. AcSPS5 was strongly expressed in the peduncle, pericarp, and core. On the basis of its abundant expression, AcSPS5 was speculated to play an important role in plant growth.