The introduction of herbicide resistant crops offers producers many more options for weed control systems. These crops allow environmentally safe, non-selective herbicides to be used as selective herbicides, broadening the spectrum of weeds controlled, while not harming the crop. As these crops are very new on the market, investigation of their performance under various environmental conditions as well as in various weed control programs is needed. Liberty-link ® soybeans are resistant to the herbicide glufosinate, because of the incorporation of a gene encoding phosphinothricin acetyl-transferase (pat), which is able to detoxify glufosinate. Roundup-Ready ® soybeans are transformed with an altered, non-sensitive form of 5-enolpyruvylshikimate- 3-phosphate synthase (EPSPS), which confers glyphosate resistance. Field and greenhouse studies were conducted to determine the efficacy of glufosinate and glyphosate on annual and perennial weeds. Also to determine whether the use of ammonium sulfate (AMS) or pelargonic acid (PA), a 9-carbon fatty acid, as additives of glufosinate or glyphosate would increase their efficacy, while maintaining their safety on the transgenic soybeans. Three annual weeds: common lambsquarters, giant foxtail, sicklepod, as well as two perennial weeds: common milkweed and horsenettle were included in studies. Uptake, translocation, and metabolism of 14C-glufosinate + AMS or PA, were studied in the five weeds in order to determine the basis for their differential weed sensitivity to glufosinate, and the effect of the two additives. The effect of temperature on Liberty-Link ® and Roundup-Ready ® soybeans after application of glufosinate or glyphosate was investigated. Injury was quantified by measuring chlorophyll content of herbicide treated soybean trifoliolates. Uptake, translocation, and metabolism studies of 14C-glufosinate and 14C-glyphosate in transgenic soybeans were conducted to determine the potential cause for the observed temperature-dependent sensitivity. Since glufosinate is a synthetic analog of a naturally occurring bacterial toxin, it was tested for possible bactericidal activity on the soybean pathogen Pseudomonas syringae. Greenhouse and field-studies showed that the 5 weeds responded differently to glufosinate and glyphosate. Common milkweed was the most tolerant to glufosinate and common lambsquarters to glyphosate while giant foxtail was the most sensitive species to both herbicides. Some interactions between AMS or PA and glufosinate or glyphosate were also observed. Uptake and translocation studies showed that AMS increased the uptake of 14C-glufosinate in some weeds, whereas PA had only minimal effects on absorption and translocation of glufosinate. Metabolism of glufosinate was detected only in common lambsquarters. A rate dependent loss of chlorophyll in Liberty-Link ® soybeans treated with glufosinate was observed that was greater at 15° C than at 25° or 35° C. Metabolism studies showed a decrease in the rate of glufosinate metabolism 3 hours after treatment in Liberty-Link ® soybeans grown at 15° C versus 25° C. Conversely, chlorophyll loss in glyphosate-treated Roundup-Ready soybeans was greater at 35° C than at 15° or 25° C. Translocation studies showed a significantly greater percentage of absorbed 14C-glyphosate translocated to developing meristems at 35° C than at 15° C in Roundup-Ready® soybeans. Glufosinate concentrations of 1 mM and higher significantly inhibited the growth of Pseudomonas syringae (L-529) in liquid media cultures. Typical field use rates of glufosinate also reduced the number of live P. syringae on Liberty-Link® soybean leaves. Overall, the results of this research show that annual and perennial weeds differ in their sensitivity to glufosinate and glyphosate. Additives such as AMS and PA may enhance the efficacy of glufosinate on perennial weed species, and glyphosate in most weeds. Differences in weed sensitivity to herbicides and effects of additives can in most cases be explained by differences in absorption or metabolism. Variable temperatures may affect the engineered resistance of transgenic soybeans to the herbicides glufosinate and glyphosate. The herbicide glufosinate has some bacteriocidal activity on P. syringae. Nomenclature: Glufosinate, 2-amino-4-(hydroxymethylphosphinyl) butanoic acid; Glyphosate, N-(phosphonomethyl)glycine; PA, pelargonic acid (nanoic acid); AMS, ammonium sulfate; giant foxtail, Setaria faberi Herrm.; common lambsquarters, Chenopodium album L.; sicklepod, Cassia obtusifolia L.; horsenettle, Solanum carolinense L.; common milkweed, Ascleipias syriaca L. pat, phosphinothricin acetyl transferase; EPSPS, 5-enolpyruvylshikimate-3-phosphate synthase. / Master of Science

面對未來全球人口成長、可耕地減少等現象，生物技術在農業上的應用日益增加。其中，基因改造技術等基因層次相關的平臺應用技術更是提升農作物價值的關鍵—透過跨物種功能應用，大幅提升育種效率。自1996年基改作物商業化種植開始至今，美國都是全球最大種植國家，也是基改作物研發先驅國家。生技農業政策以及和基因改造作物有關法規之制訂使基改作物在美國蓬勃發展，尤其是專利保護對於種子產業之影響尤為深遠。專利權所提供的完善保護使大量資本進入種子產業，投入資源將農業生物技術應用於種子培育上，此舉也促成Monsanto等跨國農業生技公司之興起，主導全球基因改造作物之市場。 Monsanto將研發重心放在基改種子之研發，其在生技種子相關營業比重遠高於同業，同時，其投入特殊性狀之基改種子研發之回收遠高於其他公司之相同營業項目之投資報酬率。Monsanto積極藉由併購取得基因、基因轉殖技術以及種子種源。掌握關鍵基因、基因轉殖技術以及大量且優良種源使含有Monsanto轉殖基因作物在市場上佔有極大的比例。在美國，超過一半以上之主要作物種植面積為基因改造作物，尤其是基因改造大豆，佔大豆總種植面積之比例高達94%。市面上絕大多數基改大豆係Monsanto的抗嘉磷塞（RounupReady，RR1Y）基改大豆種子。藉由智慧財產保護策略，Monsanto並進一步限制RR1Y及其他基改作物之使用方式。 惟RR1Y專利將在2014年到期，農民可在2014年時留種種植基改大豆種子而不用每年購買種子，或購買學名（generic）抗嘉磷塞轉基因大豆種子。在美國所種植之大豆約有四成會外銷，而外銷國家基改作物規範法規是出口與否之關鍵。若未取得歐盟、中國等主要外銷國家基改作物主管機關之批准，呈交包括基因之轉殖植物對環境衝擊之風險評估、包含該基因之轉殖植物所製成食品之安全性評估等基改作物資訊，則抗嘉磷塞基因大豆無法進入該國糧食市場。然而，在目前美國農業生技基改作物相關規範下，學名基改種子廠必須在專利種子專利到期後，才能進行實驗及田間試驗，呈交相關資料以符合基改作物主管機關之要求。透過建立學名基改作物快速獲得核准查驗登記之程序，允許學名廠依賴專利基改作物原廠之實驗及田間試驗資料以建立其學名基改作物之安全性與性狀表現有效性，同時，允許學名基改作物在原基改作物開發廠專利期滿前即可開始進行試驗，可以使學名抗嘉磷塞大豆種子以及其他學名基改種子能在原專利基改作物種子專利到期後順利進入市場，促使基改作物種子價格競爭，並對於專利基改作物研發公司進行適度之補償，以促進產業發展。 / The development of new technologies in plant breeding has led to improvements in the efficiency scientists produce improved plant varieties. Genetic modification is among the developments that support plant breeding. The introduction of genetically modified crops has revolutionized the agriculture industry. With patent protection available on GM traits, varieties and other aspects of seed production, private R&D investments in the seed industry have increased tremendously. Monsanto has been the leading company in investing agricultural biotechnology and has obtained a dominant position in the GM traits found in soybeans, cotton, corn and other commercialized crops. Currently, over 90 percent of soybeans planted in the United States were herbicide-resistant, with Monsanto’s Roundup Ready being the dominant soybeans planted. In 2014, however, the agriculture industry will be facing the expiration of a patent for Roundup Ready soybeans. Despiate the fact that the patent expiration date is approaching, the agricultural biotech industry has no guideline in place to tell its players exactly how to transition seamlessly from patent monopolies to generic competition. The transition problem is espectially significant for soybeans exported to oversea markets as more than 40 percent of the soybeans grown in the U.S. are exported. In order for those soybeans to be accepted in the grain channel, regulatory approvals are required in countries that import soybeans. Obtaining data, which includes scitific data on the trait being developed, for regulatory approvals can take years to complete. If a generic trait is to reach market immediately after the original trait go off patent, the data generation process should begin before patent expiration. A Hatch-Waxman type patent infringement defense for activities necessary to obtain regulatory approvals for biotech traits can ensure that seed companies have sufficient time to obtain registrations for a generic Roundup Ready trait or other generic traits. Current legislation should be modified to adequately oversee the transition to the generic use of genetically modified crops and, in the mean time, ensure the availability of generic modified crops.