The high-affinity pineapple sucrose transporter AcSUT1B, regulated by AcCBF1, exhibited enhanced cold tolerance in transgenic Arabidopsis.

Sucrose transporter (SUT) plays essential roles in plant growth and development, as well as responses to diverse abiotic stresses. However, limited information about the function of SUT was available in pineapple, an important tropical fruit crop with crassulacean acid metabolism. Here, four AcSUT genes were identified in pineapple genome, and divided into three clades according to the phylogenetic analysis. The expression profiles of AcSUTs were systemically examined, and they were all localized to plasma membrane. Transport activity assay by two-electrode voltage clamp of Xenopus oocytes showed that AcSUT1A and AcSUT1B were capable of transporting a range of glucosides, and they were exhibited high affinity for sucrose with Km value of 0.09 mM and 0.41 mM at pH 5.0, respectively. Overexpression of the cold-induced AcSUT1B conferred enhanced cold tolerance in transgenic Arabidopsis. DNA-protein interaction analysis further demonstrated that AcCBF1 directly binds the CRT/DRE element of the AcSUT1B promoter and activated its expression. Heterologous expression of AcCBF1 in Arabidopsis also increased cold tolerance. In this study, we investigated the transport activities of AcSUTs in pineapple and identified the AcCBF1-AcSUT1B module involved in cold stress, which provided new insights into the molecular mechanism of the cold response in pineapple.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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