title: Seasonal expression of Bt proteins in transgenic rice lines and the resistance against Asiatic rice borer Chilo suppressalis (Walker).
abstract: Laboratory bioassays and field surveys were carried out to compare the resistance of three transgenic rice (Oryza sativa L.) lines including Bt-DL expressing a single gene cry1Ab, Bt-KF6 expressing stacked genes cry1Ac and CpTI genes and Bt-SY63  expressing a fusion gene cry1Ab/cry1Ac, respectively, to an important rice pest Chilo suppressalis (Walker). In addition, enzyme-linked immunosorbent assays (ELISA) were conducted to monitor the Bt protein expressions in rice leaves and stems at different rice growth stages.  Results showed that all the transgenic rice lines exhibited significantly high resistance to the pest compared with their corresponding nontransformed isolines. Among the transgenic rice lines, Bt-SY63 and Bt-KF6 had higher resistance to C. suppressalis at early growth stage,  but lower resistance at late stages, while the pest resistance of Bt-DL was relatively stable throughout the growing season. The results were consistent with ELISA results showing that Bt protein levels in Bt-SY63 or Bt-KF6 leaves decreased in late growth stages,  but were relatively stable in Bt-DL at all growth stages. This demonstrates that the resistance to a pest by Bt plants is positively correlated with Cry protein expression levels in plant tissues. Compared with Bt-SY63 and Bt-KF6, the Bt protein expression  levels were significantly lower in Bt-DL, while its resistance to C. suppressalis was the highest. This may suggest that C. suppressalis is more susceptible to Cry1Ab than to Cry1Ac. The data from the current study are valuable for decision-making for commercial use of Bt rice  lines and development of appropriate pest control and resistance management strategies for the transgenic rice lines.
authors.affiliation: State Key Laboratory of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Science, Beijing, P R China.
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yunhe
authors.initials: Y
authors.lastname: Li
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yang
authors.initials: Y
authors.lastname: Chen
authors.forename: Kongming
authors.initials: K
authors.lastname: Wu
authors.forename: Yufa
authors.initials: Y
authors.lastname: Peng
authors.forename: Yuyuan
authors.initials: Y
authors.lastname: Guo
mesh_terms: D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004731:Endotoxins / Q000235:genetics / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D006460:Hemolysin Proteins / Q000235:genetics / Q000378:metabolism*; D006790:Host-Parasite Interactions; D009036:Moths / Q000502:physiology*; D012275:Oryza / Q000235:genetics / Q000378:metabolism / Q000469:parasitology*; D010572:Pest Control, Biological; D030821:Plants, Genetically Modified / Q000378:metabolism / Q000469:parasitology
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis