title: HbNIN2, a cytosolic alkaline/neutral-invertase, is responsible for sucrose catabolism in rubber-producing laticifers of Hevea brasiliensis (para rubber tree).
abstract: In Hevea brasiliensis, an alkaline/neutral invertase (A/N-Inv) is responsible for sucrose catabolism in latex (essentially the cytoplasm of rubber-producing laticifers, the source of natural rubber) and implicated in rubber yield. However, neither the gene encoding this enzyme nor its molecular and biochemical properties have been well documented. Three Hevea A/N-Inv genes, namely HbNIN1, 2 and 3, were first cloned and characterized in planta and in Escherichia coli. Cellular localizations of HbNIN2 mRNA and protein were probed. From latex, active A/N-Inv proteins were purified, identified, and explored for enzymatic properties. HbNIN2 was identified as the major A/N-Inv gene functioning in latex based on its functionality in E. coli, its latex-predominant expression, the conspicuous localization of its mRNA and protein in the laticifers, and its expressional correlation with rubber yield. An active A/N-Inv protein was partially purified from latex, and determined as HbNIN2. The enhancement of HbNIN2 enzymatic activity by pyridoxal is peculiar to A/N-Invs in other plants. We conclude that HbNIN2, a cytosolic A/N-Inv, is responsible for sucrose catabolism in rubber laticifers. The results contribute to the studies of sucrose catabolism in plants as a whole and natural rubber synthesis in particular.
authors.affiliation: Rubber Research Institute, Chinese Academy of Tropical Agricultural Sciences, Danzhou, 571737, Hainan, China; College of Agronomy, Hainan University, Haikou, 570228, Hainan, China.
authors.forename: Shujin
authors.initials: S
authors.lastname: Liu
authors.forename: Jixian
authors.initials: J
authors.lastname: Lan
authors.forename: Binhui
authors.initials: B
authors.lastname: Zhou
authors.forename: Yunxia
authors.initials: Y
authors.lastname: Qin
authors.forename: Yihua
authors.initials: Y
authors.lastname: Zhou
authors.forename: Xiaohu
authors.initials: X
authors.lastname: Xiao
authors.forename: Jianghua
authors.initials: J
authors.lastname: Yang
authors.forename: Jiqing
authors.initials: J
authors.lastname: Gou
authors.forename: Jiyan
authors.initials: J
authors.lastname: Qi
authors.forename: Yacheng
authors.initials: Y
authors.lastname: Huang
authors.forename: Chaorong
authors.initials: C
authors.lastname: Tang
mesh_terms: D000595:Amino Acid Sequence; D003600:Cytosol / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D028482:Hevea / Q000166:cytology / Q000201:enzymology* / Q000235:genetics; D007840:Latex / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018547:Plant Stems / Q000166:cytology / Q000201:enzymology / Q000235:genetics; D016415:Sequence Alignment; D013395:Sucrose / Q000378:metabolism*; D043324:beta-Fructofuranosidase / Q000235:genetics / Q000378:metabolism*
chemical_list: D007840:Latex; D010940:Plant Proteins; D013395:Sucrose; D043324:beta-Fructofuranosidase
keywords: Hevea brasiliensis (para rubber tree); alkaline/neutral invertase (A/N-Inv) HbNIN2; enzymatic characters; gene expression; rubber productivity; rubber-producing laticifers; sucrose catabolism