Picloram Resistance in Transgenic Tobacco Expressing an Anti-Picloram scFv Antibody Is Due to Reduced Translocation

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• 作者：Jonathan Horsman ; Michael D. McLean ; Fernando C. Olea-Popelka ; J. Christopher Hall
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2007
• 出版时间：January 10, 2007
• 年：2007
• 卷：55
• 期：1
• 页码：106 - 112
• 全文大小：409K
• 年卷期：v.55,no.1(January 10, 2007)
• ISSN：1520-5118

文摘

Picloram resistance exhibited by transgenic tobacco (Nicotiana tabacum) plants expressing an anti-picloram single-chain variable fragment (scFv) antibody was investigated through the study ofhomozygous lines expressing the antibody. Dose-response bioassays, using foliar application ofpicloram, showed that these homozygous transgenic plants were resistant to at least 5 g of ai ha^-1picloram and grew normally to produce seed, whereas wild-type plants did not survive. Althoughthese lines had improved resistance compared with those previously reported, significant improvementsare still required to achieve field-level resistance. Uptake and translocation studies demonstratedthat [¹⁴C]picloram translocation from treated leaves to the apical meristem was reduced in transgenicversus wild-type plants. The presence of [¹⁴C]picloram, visualized by autoradiography and quantifiedby liquid scintillation spectrometry, demonstrated the distribution of more picloram in the treated leafand less in the apical meristem of transgenic plants when compared to wild-type plants. No differencesbetween transgenic and wild-type plants were found in the distribution of [¹⁴C]clopyralid, a herbicidewith structural similarity to picloram as well as the same mechanism of action. No differences werefound in the metabolism of [¹⁴C]picloram. Taken together, these results suggest that reducedtranslocation to the site of action is a major mechanism responsible for picloram resistance in tobaccoplants expressing this anti-picloram antibody.