Plant biotech & Risk Assessment
Takahashi, Kana , Zhang, Qin , Meetam, Metha , Masaaki, Sakuta , Riechers, Dean , Goldsbrough, Peter .
Manipulating the expression of glutathione S-transferases to modify herbicide tolerance.
Glutathione S-transferases (GSTs) participate in the detoxification of herbicides and other toxins by catalyzing the conjugation of these compounds to glutathione (GSH). Herbicide safeners are used to protect crop plants from herbicide injury. Safeners function by stimulating the expression of GSTs and other components of the detoxification system. We have previously shown that treatment of Arabidopsis plants with safeners induces GSTs but does not protect against herbicide injury. To understand why safeners fail to protect Arabidopsis we have expressed GSTs from Arabidopsis (AtGSTU19), Triticum tauschii (TtGSTU1), or maize (ZmGST4) in transgenic Arabidopsis plants. Plants expressing ZmGST4 using the 35S promoter are highly tolerant to chloroacetamide herbicides in a variety of assays. These plants also show significant GSH-conjugating activity with dimethenamid, a chloroacetamide herbicide. In contrast, plants that overexpress AtGSTU19 show increased GST activity with CDNB but not dimethenamid, and are as susceptible to herbicide injury as non-transgenic plants. Constitutive expression of TtGSTU1 provides some herbicide tolerance but is not as effective as ZmGST4. Therefore, the inability of safeners to protect Arabidopsis results from a failure to induce GSTs that can efficiently metabolize chloroacetamide herbicides. ZmGST4 has also been expressed using other tissue-specific promoters. Preliminary experiments indicate that expression of this GST in shoot or epidermal tissues is sufficient to provide tolerance to pre-emergent application of alachlor in soil.
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1 - Ochanomizu University, Biology
2 - University of Illinois, Crop Sciences
3 - Purdue University, Botany and Plant Pathology
4 - Purdue University, Botany and Plant Pathology, Lilly Hall, 915 W State Street, West Lafayette, IN, 47907, United States
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM