Conclusion

In this study, for the first time, a functional sucrose-specific active transporter, Ge SUT4, was identified that contributes to the carbon flow in a fully mycoheterotrophy orchid,
G. elata. Localization of Ge SUT4 proteins on both the plasma-membrane and tonoplast combined with physiological studies in transgenic Arabidopsis indicate that this sucrose transporter imports carbon from Armillaria fungal cells and also maintains intracellular sucrose homeostasis. Even in the absence of photosynthesis and a vascular translocation system, our studies demonstrate the similarity in sucrose allocation mechanisms between the mycoheterotrophic Gastrodia and autotropic plants, highlighting the evolutionary importance of sucrose transporters in carbon allocation.
Supplemental DataThe following supplemental materials are available. Figure S1. Pictures of developing G. elata tubes.
Figure S2. Phylogenetic tree of SUT transporters. Figure S3. Gene properties of Gastrodia GeSUT genes.
Figure S4. Phylogenetic tree of genes involved in sucrose metabolism fromGastrodia. Figure S5. Transport activity of GeSUT4 to hexoses in yeast. Figure S6. The uptake activity of GeSUT4 to maltose. Figure S7. Localization of GeSUT4 expression. Figure S8. Leaf areas of transgenic Arabidopsis overexpressing GeSUT4. Figure S9. Roots growth of transgenic Arabidopsis overexpressing GeSUT4.