Producing mimosine-free Leucaena leucocephala through metabolic pathway engineering

主要研究人员（pi）试图通过代谢途径工程开发一种不含胺芥子酸的鱼青藻，这种鱼青藻可以作为饲料使用，对动物没有任何有害的副作用。Leucaena Leucaena leucaphala （Leucaena Leucaena）是许多热带和亚热带国家重要的农林业豆科树木。银合欢被称为“热带的紫花苜蓿”，因为其叶片的高蛋白含量与紫花苜蓿相当。然而，银合欢属植物含有一种毒素，对动物有害。生产不含蜜胺的银合欢是一项具有挑战性的任务，因为银合欢的生物合成途径尚不清楚，而且银合欢不易转化。一种新的代谢工程策略将被用于通过引入其细菌共生体的基因来去除青藻中的含羞草胺。该项目将使用两个根瘤菌基因，这两个基因是降解3-羟基-4-吡啶酮（HP）所必需的，HP是青合藻生物合成氨基糖的前体。通过在转基因银合乐中表达这些基因，将使含羞草胺的代谢途径重新定向，产生氨、丙酮酸和甲酸盐，这些物质可以作为植物额外的氮和碳源。这项工作将为利用代谢工程方法中和其他豆科植物和非豆科植物中的毒素开辟道路。夏威夷是全年测试生物工程作物的最佳地点，为此需要许多科学家和训练有素的技术人员。这个项目将通过培养两名研究生和六名或更多的生物技术本科生，帮助在不久的将来培养一批科学家。将作出特别努力，通过这个项目招收夏威夷土著和其他太平洋岛屿学生进行培训。该项目还将通过培训24名科学教师来加强夏威夷的生物技术教育。教师将学习生物技术的最新发展，然后将这些知识传授给学生。生物技术教育对于激发高中生对这一迅速发展的技术的兴趣至关重要。如果没有适当的生物技术教育，公众可能会吸收对生物技术、转基因作物及其在夏威夷进行的试验的负面宣传，这始终是一种危险。

CBET-0827057BorthakurThe Principal Investigators (PIs) seek to develop, through metabolic pathway engineering, a mimosine-free leucaena that can be used as a fodder without any harmful side effects to animals. Leucaena leucocephala (leucaena) is an important leguminous tree for agro-forestry in many tropical and subtropical countries. Leucaena is known as "the alfalfa of the tropics" since the high protein content of its foliage is comparable to that of alfalfa. However, leucaena plants contain a toxin, mimosine, which is harmful to animals. Producing mimosine-free leucaena is a challenging task because the biosynthetic pathway for mimosine is unknown and leucaena is recalcitrant to transformation. A novel metabolic engineering strategy will be used for removing mimosine from leucaena by introducing genes from its bacterial symbiont. This project will use two Rhizobium genes that are required for degradation of 3-hydroxy-4-pyridone (HP), which is a precursor for mimosine biosynthesis in leucaena. By expressing these genes in transgenic leucaena, the metabolic pathway for mimosine will be redirected to produce ammonia, pyruvate and formate, which should serve as additional nitrogen and carbon sources for the plant.This work will lead the way for neutralization of toxins in other legumes and non-legumes using metabolic engineering approaches. Hawaii is a prime location for testing bioengineered crops throughout the year, for which many scientists and trained technicians are needed. This project will help to create a group of scientists for the near future by training two graduate and six or more undergraduate students in biotechnology. Special efforts will be made to recruit the native Hawaiian and other Pacific Island students for training through this project. This project will also enhance biotechnology education in Hawaii by training 24 science teachers. Teachers will learn the latest developments in biotechnology, which will be then transmitted to the students. Biotechnology education is essential to stimulate interest of high school students to this rapidly growing technology. Without proper biotechnology education there is always a danger that the public may absorb negative publicity against biotechnology, transgenic crops, and their testing in Hawaii.