Sugarcane is capable to store large amounts of sucrose in the culm at maturity hence it became a major source of sucrose for the food and the renewable energy industries. Sucrose, the main disaccharide produced by photosynthesis, is mainly stored in the vacuole of the cells of non-photosynthetic tissues. Two pathways are known to release free sucrose in plant cells, one is de novo synthesis dependent on sucrose phosphate synthase (SPS) and sucrose phosphate phosphatase (S6PP) while the other is regulatory and dependent on sucrose synthase (SuSy) activity. The molecular understanding of genes that give rise to the expression of the enzyme sucrose phosphate phosphatase, responsible for the release of sucrose in the last synthetic step lag behind the regulatory SuSy gene. Sugarcane genome sequencing effort disclosed the existence of a tandem duplication and the present work further support that both S6PP.1 and S6PP_2D isoforms are actively transcribed in young sugarcane plants but significantly less at maturity. Two commercial hybrids (SP80–3280 and R570) and both Saccharum spontaneum (IN84–58) and S.officinarum (BADILLA) exhibit transcriptional activity at three-month-old plants of the tandem S6PP_2D in leaves, culm, meristem and root system with a cultivar-specific distribution. Moreover, this tandem duplication is shared with other grasses and is ancestral in the group. Detection of a new isoform of S6PP resulting from the translation of 14 exon-containing transcript (S6PP_2D) will contribute to the knowledge of sucrose metabolism in plants. In addition, expression varies along plant development and between sugarcane cultivars and parental species.

中文翻译：

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来自甘蔗的蔗糖磷酸酶揭示了祖先的串联重复

甘蔗在成熟时能够在茎秆中储存大量蔗糖，因此它成为食品和可再生能源行业的主要蔗糖来源。蔗糖是光合作用产生的主要双糖，主要储存在非光合组织细胞的液泡中。已知有两种途径在植物细胞中释放游离蔗糖，一种是依赖蔗糖磷酸合酶 (SPS) 和蔗糖磷酸磷酸酶 (S6PP) 的从头合成，而另一种是调节性的，依赖于蔗糖合酶 (SuSy) 活性。对引起蔗糖磷酸磷酸酶表达的基因的分子理解落后于调节性 SuSy 基因，该酶负责在最后的合成步骤中释放蔗糖。甘蔗基因组测序工作揭示了串联重复的存在，目前的工作进一步支持 S6PP.1 和 S6PP_2D 同种型在年轻的甘蔗植物中积极转录，但在成熟时明显减少。两个商业杂种（SP80-3280 和 R570）以及 Saccharum spontaneum (IN84-58) 和 S.officinarum (BADILLA) 在 3 个月大的串联 S6PP_2D 植物的叶、茎、分生组织和根系中表现出转录活性特定品种的分布。此外，这种串联重复与其他草共享，并且是群体中的祖先。检测由 14 个含外显子转录物 (S6PP_2D) 翻译产生的新 S6PP 同种型将有助于了解植物中的蔗糖代谢。此外，