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

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