title: Cloning of a putative extracellular Cu/Zn superoxide  dismutase and functional differences of superoxide  dismutases in invasive and indigenous whiteflies.
abstract: Superoxide dismutases (SODs) are a group of important antioxidant defense enzymes. In this study, a putative extracellular Cu/Zn superoxide dismutase (ecCuZnSOD) complementary DNA was cloned and characterized from the whitefly, Bemisia tabaci. Quantitative polymerase chain reaction analysis showed that the expression level of BtecCuZnSOD was more than 10-fold higher in the invasive Middle East Asia Minor 1 (MEAM1) than in the native Asia II 3 species of the B. tabaci species complex. After exposure to low temperature (4 °C), the expression of Bt-ecCuZnSOD gene was significantly up-regulated in MEAM1 but not in Asia II 3. Furthermore, the expression level of B. tabaci intracellular CuZnSOD (Bt-icCuZnSOD), Bt-ecCuZnSOD and mitochondrial MnSOD (Bt-mMnSOD) was compared after transferring MEAM1 and Asia II 3 whiteflies from favorable (cotton) to unfavorable host plants (tobacco). On cotton, both CuZnSOD genes were expressed at a higher level in MEAM1 compared with Asia II 3. Interestingly, after transferring onto tobacco, the expression of Bt-ecCuZnSOD was significantly induced in Asia II 3 but not in MEAM1. On the other hand, while Bt-mMnSOD was expressed equally in both species on cotton, Bt-mMnSOD messenger RNA was up-regulated in MEAM1 on tobacco. Consistently, enzymatic activity assays of CuZnSOD and MnSOD demonstrated that CuZnSOD might play an important protective role against oxidative stress in Asia II 3, whereas MnSOD activation was critical for MEAM1 whiteflies during host adaptation. Taken together, our results suggest that the successful invasion of MEAM1 is correlated with its constitutive high activity of CuZnSOD and inducible expression of MnSOD under stress conditions.
authors.forename: Xian-Long
authors.initials: XL
authors.lastname: Gao
authors.forename: Jun-Min
authors.initials: JM
authors.lastname: Li
authors.forename: Hong-Xing
authors.initials: HX
authors.lastname: Xu
authors.forename: Gen-Hong
authors.initials: GH
authors.lastname: Yan
authors.forename: Min
authors.initials: M
authors.lastname: Jiu
authors.forename: Shu-Sheng
authors.initials: SS
authors.lastname: Liu
authors.forename: Xiao-Wei
authors.initials: XW
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D018076:DNA, Complementary; D015870:Gene Expression; D003368:Gossypium / Q000469:parasitology; D006430:Hemiptera / Q000201:enzymology* / Q000235:genetics; D006790:Host-Parasite Interactions; D058865:Introduced Species; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D012333:RNA, Messenger; D060888:Real-Time Polymerase Chain Reaction; D013482:Superoxide Dismutase / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D013696:Temperature; D014026:Nicotiana / Q000469:parasitology
chemical_list: D018076:DNA, Complementary; D012333:RNA, Messenger; D013482:Superoxide Dismutase