title: Leaf morphology and ultrastructure responses to elevated O3 in transgenic Bt (cry1Ab/cry1Ac) rice and conventional rice under fully open-air field conditions.
abstract: BACKGROUND
  Elevated tropospheric ozone severely affects not only yield but also the morphology, structure and physiological functions of plants. Because of concerns regarding the potential environmental risk of transgenic crops, it is important to monitor changes in transgenic insect-resistant rice under the projected high tropospheric ozone before its commercial release.
  
  
  RESULTS
  Using a free-air concentration enrichment (FACE) system, we investigated the changes in leaf morphology and leaf ultrastructure of two rice varieties grown in plastic pots, transgenic Bt Shanyou 63 (Bt-SY63, carrying a fusion gene of cry1Ab and cry1Ac) and its non-transgenic counterpart (SY63), in elevated O3 (E-O3) versus ambient O3 (A-O3) after 64-DAS (Days after seeding), 85-DAS and 102-DAS. Our results indicated that E-O3 had no significant effects on leaf length, leaf width, leaf area, stomatal length and stomatal density for both Bt-SY63 and SY63. E-O3 increased the leaf thickness of Bt-SY63, but decreased that of SY63. O3 stress caused early swelling of the thylakoids of chloroplasts, a significant increase in the proportion of total plastoglobule area in the entire cell area (PCAP) and a significant decrease in the proportion of total starch grain area in the entire cell area (SCAP), suggesting that E-O3 accelerated the leaf senescence of the two rice genotypes. Compared with SY63, E-O3 caused early swelling of the thylakoids of chloroplasts and more substantial breakdown of chloroplasts in Bt-SY63.
  
  
  CONCLUSIONS
  Our results suggest that the incorporation of cry1Ab/Ac into SY63 could induce unintentional changes in some parts of plant morphology and that O3 stress results in greater leaf damage to Bt-SY63 than to SY63, with the former coupled with higher O3 sensitivity in CCAP (the proportions of total chloroplast area in the entire cell area), PCAP and SCAP. This study provides valuable baseline information for the prospective commercial release of transgenic crops under the projected future climate.
authors: College of Forest Resources and Environment, Nanjing Forestry University, Nanjing, Jiangsu, China ; Key Biosafety Laboratory in Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection of China, Nanjing, Jiangsu, China ; Liaoning Agricultural College, Yingkou, Liaoning, China.
authors: Chunyan
authors: C
authors: Li
authors: Biao
authors: B
authors: Liu
authors: Chunhua
authors: C
authors: Li
authors: Qing
authors: Q
authors: Zeng
authors: Mingzhuo
authors: M
authors: Hao
authors: Zhengmin
authors: Z
authors: Han
authors: Jianguo
authors: J
authors: Zhu
authors: Xiaogang
authors: X
authors: Li
authors: Wenjing
authors: W
authors: Shen
mesh_terms: D000383:Agriculture; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000378:metabolism*; D002473:Cell Wall / Q000187:drug effects; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D004731:Endotoxins / Q000378:metabolism*; D006460:Hemolysin Proteins / Q000378:metabolism*; D058503:Mesophyll Cells / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure; D012275:Oryza / Q000033:anatomy & histology* / Q000187:drug effects / Q000235:genetics* / Q000648:ultrastructure; D010126:Ozone / Q000494:pharmacology*; D018515:Plant Leaves / Q000033:anatomy & histology* / Q000187:drug effects / Q000648:ultrastructure*; D054046:Plant Stomata / Q000033:anatomy & histology / Q000187:drug effects; D030821:Plants, Genetically Modified
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis; D010126:Ozone