title: Reduced contamination by the Fusarium mycotoxin zearalenone in maize kernels through genetic modification with a detoxification gene.
abstract: Maize is subject to ear rot caused by toxigenic Aspergillus and Fusarium species, resulting in contamination with aflatoxins, fumonisins, trichothecenes, and zearalenone (ZEN). The trichothecene group and ZEN mycotoxins are produced by the cereal pathogen Fusarium graminearum. A transgenic detoxification system for the elimination of ZEN was previously developed using an egfp::zhd101 gene (gfzhd101), encoding an enhanced green fluorescent protein fused to a ZEN-degrading enzyme. In this study, we produced a transgenic maize line expressing an intact copy of gfzhd101 and examined the feasibility of transgene-mediated detoxification in the kernels. ZEN-degrading activity has been detected in transgenic kernels during seed maturation (for a period of 6 weeks after pollination). The level of detoxification activity was unaltered after an additional storage period of 16 weeks at 6 degrees C. When the seeds were artificially contaminated by immersion in a ZEN solution for 48 h at 28 degrees C, the total amount of the mycotoxin in the transgenic seeds was uniformly reduced to less than 1/10 of that in the wild type. The ZEN in the transgenic maize kernels was also efficiently decontaminated under conditions of lower water activity (aw) and temperature; e.g., 16.9 microg of ZEN was removed per gram of seed within 48 h at an aw of 0.90 at 20 degrees C. F. graminearum infection assays demonstrated an absence of ZEN in the transgenic maize seeds, while the mycotoxin accumulated in wild-type kernels under the same conditions. Transgene-mediated detoxification may offer simple solutions to the problems of mycotoxin contamination in maize.
authors.affiliation: Plant & Microbial Metabolic Engineering Research Unit and Laboratory for Remediation Research, Discovery Research Institute (DRI), RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Igawa
authors.forename: Naoko
authors.initials: N
authors.lastname: Takahashi-Ando
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Ochiai
authors.forename: Shuichi
authors.initials: S
authors.lastname: Ohsato
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Shimizu
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Kudo
authors.forename: Isamu
authors.initials: I
authors.lastname: Yamaguchi
authors.forename: Makoto
authors.initials: M
authors.lastname: Kimura
mesh_terms: D001709:Biotechnology / Q000379:methods; D003666:Decontamination / Q000379:methods*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D005670:Fusarium / Q000378:metabolism / Q000472:pathogenicity*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006867:Hydrolases / Q000235:genetics / Q000378:metabolism; D008658:Inactivation, Metabolic / Q000235:genetics*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000382:microbiology*; D015202:Protein Engineering / Q000379:methods; D012639:Seeds / Q000235:genetics* / Q000382:microbiology; D003313:Zea mays / Q000235:genetics* / Q000382:microbiology; D015025:Zearalenone / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D015025:Zearalenone; D006867:Hydrolases; C460562:Zhd101 protein, Bionectria ochroleuca