title: The sucrose transporter HbSUT3 plays an active role in sucrose loading to laticifer and rubber productivity in exploited trees of Hevea brasiliensis (para rubber tree).
abstract: Efficient sucrose loading in rubber-producing cells (laticifer cells) is essential for retaining rubber productivity in Hevea brasiliensis, but the molecular mechanisms underlying the regulation of this process remain unknown. Here, we functionally characterized a putative Hevea SUT member, HbSUT3, mainly in samples from regularly exploited trees. When expressed in yeast, HbSUT3 encodes a functional sucrose transporter that exhibits high sucrose affinity with a K(m) value of 1.24 mm at pH 4.0, and possesses features typical of sucrose/H(+) symporters. In planta, when compared to the expression of other Hevea SUT genes, HbSUT3 was found to be the predominant member expressed in the rubber-containing cytoplasm (latex) of laticifers. The comparison of HbSUT3 expression among twelve Hevea tissues demonstrates a relatively tissue-specific pattern, i.e. expression primarily in the latex and in female flowers. HbSUT3 expression is induced by the latex stimulator Ethrel (an ethylene generator), and relates to its yield-stimulating effect. Tapping (the act of rubber harvesting) markedly increased the expression of HbSUT3, whereas wounding alone had little effect. Moreover, the expression of HbSUT3 was found to be positively correlated with latex yield. Taken together, our results provide evidence favouring the involvement of HbSUT3 in sucrose loading into laticifers and in rubber productivity.
authors.affiliation: Key Lab of Rubber Biology, Ministry of Agriculture & Rubber Research Institute, Chinese Academy of Tropical Agricultural Sciences, College of Agronomy, Hainan University, Danzhou, Hainan 571737, China. chaorongtang@126.com
authors.forename: Chaorong
authors.initials: C
authors.lastname: Tang
authors.forename: Debao
authors.initials: D
authors.lastname: Huang
authors.forename: Jianghua
authors.initials: J
authors.lastname: Yang
authors.forename: Shujin
authors.initials: S
authors.lastname: Liu
authors.forename: Soulaïman
authors.initials: S
authors.lastname: Sakr
authors.forename: Heping
authors.initials: H
authors.lastname: Li
authors.forename: Yihua
authors.initials: Y
authors.lastname: Zhou
authors.forename: Yunxia
authors.initials: Y
authors.lastname: Qin
mesh_terms: D001692:Biological Transport; D003001:Cloning, Molecular; D015870:Gene Expression / Q000187:drug effects; D017343:Genes, Plant; D028482:Hevea / Q000235:genetics / Q000378:metabolism*; D007840:Latex / Q000096:biosynthesis; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009943:Organophosphorus Compounds / Q000494:pharmacology; D018749:RNA, Plant; D012408:Rubber / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D013395:Sucrose / Q000378:metabolism*
chemical_list: D007840:Latex; D026901:Membrane Transport Proteins; D009943:Organophosphorus Compounds; D018749:RNA, Plant; D013395:Sucrose; D012408:Rubber; C005073:ethephon