Article Highlight | 4-Feb-2024

Unlocking the sweet secrets of pineapple: Discovering the role of SWEET10 in glucose transport and plant fertility

BioDesign Research

SWEET transporters, recently identified as key sugar transporters, play crucial roles in plant developmental and physiological processes, with established functions in model plants like Arabidopsis. These transporters, known for their unique ability to facilitate sugar mobility across various plant tissues, have been structurally elucidated, highlighting their evolutionary advancement from prokaryotic semiSWEETs to complex eukaryotic forms. Despite significant advancements in in model species, the exploration of SWEET transporters in economically significant crops, such as pineapple, remains underexplored.

In April 2023, Horticulture Research published a research entitled by “Pineapple SWEET10 is a glucose transporter”. The study reveals a close structural and evolutionary relationship between pineapple SWEET transporters and those in Arabidopsis, highlighting similarities in sequence identity and substrate preferences for glucose and sucrose.

The phylogenetic tree was constructed using existing information from rice, grape, maize, Arabidopsis, and pineapple to determine the close relatedness of SWEET transporters. The pineapple SWEETs exhibit a high sequence similarity to well-characterized glucose and sucrose transporters, suggesting their potential target sugar for transport. Further investigation into the 3D structures of selected pineapple SWEET proteins, such as AcSWEET6, 8, and 10, confirmed their structural resemblance to AtSWEET8, a well-characterized glucose transporter in Arabidopsis. This resemblance supported the hypothesis that these pineapple SWEETs could facilitate glucose transport, which was further validated through subcellular localization studies indicating their plasma membrane localization.

The functional characterization of these transporters was extended through yeast complementation assays, which demonstrated that AcSWEET10, in particular, possesses a high affinity for glucose transport. Additionally, site-directed mutagenesis experiments targeting conserved amino acids crucial for glucose transport further underscored the functional importance of specific residues in facilitating glucose movement across the membrane. The study's findings explored not only the molecular level, but also the transporters' role in pollen development, showing that AcSWEET10's expression could rescue the fertility defects in an Arabidopsis sweet8 mutant.

In summary, this research provides insights into the substrate specificity and functional roles of pineapple SWEET transporters as well as highlights the critical influence of the C-terminal region on transporter activity. This study reveals the structural and functional parallels between pineapple and Arabidopsis SWEET proteins, providing valuable insights into sugar transport mechanisms in plants, with implications for improving crop yield and quality through targeted manipulation of sugar transport pathways.

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References

Authors

Beenish Fakher1,2, M. Arif Ashraf3, Lulu Wang1,2, Xiaomei Wang4, Ping Zheng2, Mohammad Aslam2,5, * and Yuan Qin 2, *

Affiliations

1State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi Key Lab of Sugarcane Biology, College of Agriculture, Guangxi University, Nanning 530004, Guangxi, China

2College of Life Sciences, Key Laboratory of Genetics, Breeding and Multiple Utilization of Crops, Ministry of Education, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China

3Department of Biology, Howard University, Washington DC 20059, USA

4Horticulture Research Institute, Guangxi Academy of Agricultural Sciences, Nanning Investigation Station of South Subtropical Fruit Trees, Ministry of Agriculture, Nanning 530004, China

5Donald Danforth Plant Science Center, Saint Louis, MO 63132, USA

About Yuan Qin

Dean of Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, College of Agriculture, Fujian Agriculture and Forestry University. Her research focuses on the molecular mechanisms of female gametophyte development and the molecular regulation of plant stress development.

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