权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Towards incorporating the biosynthetic transformation required for Striga inhibition from Desmodium into edible legume intercrops

将山金钱草抑制独脚金所需的生物合成转化纳入食用豆类间作作物中

基本信息

批准号：
BB/F003986/1
负责人：
Antony Hooper
金额：
$ 78.89万
依托单位：
Rothamsted Research
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2008
资助国家：
英国
起止时间：
2008 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FF003986%2F1
关键词：
Towards incorporating biosynthetic transformation required

项目摘要

In sub-Saharan savannah agriculture, a primary activity is the cultivation of maize as a subsistence crop. The farmers are resource poor and have a range of problems with which to contend, in particular the loss of yield due to damage by insect pests (stem-borers) and parasitic weeds (striga). The insect stem-borers are the caterpillars of indigenous and introduced moths, and attack maize stems causing extensive damage and even the loss of the plant by collapse. During the course of work on controlling insect pests, by intercropping with repellent plants and trap cropping with plants that attract the adult moths away from the maize, an intercrop was found that provided dramatic control of striga. These parasitic weeds from the Striga genus are in the snapdragon family and are a major threat to the staple food crops of over 100 million people in the region. The striga-controlling intercrops were cattle forage legumes, commonly called desmodium, and when grown on-farm as a one-to-one intercrop between maize and other subsistence cereals such as sorghum, the parasitic striga was controlled to the extent that a yield of well under 1 tonne/hectare of maize could be raised to over 5 tonnes/hectare. To show this protection was based on chemicals generated from the root system of desmodium, it was demonstrated that the effect could be provided by passing water over the roots of desmodium and then into soil containing the striga and maize seeds. Furthermore, when desmodium was grown in water with nutrients but without soil (hydroponically), the water captured the activity, which could then be transferred to the striga and maize seeds in soil, and again conferred control of the parasite. The chemical composition from the water effecting this control has been studied and fractions of the content separated from each other. After the striga seed germinates, a radicle (root) is produced that will develop into the attachment organ for parasitism of maize. However, one particular fraction causes interference with the development of the radicle and from this we have identified a potent radicle inhibitor. The structure of this compound is a di-C-glycosylflavone called isoschaftoside. Many plants possess the ability to produce flavones, however the glycosylation steps required to produce isoschaftoside are unusual. We propose to identify the enzyme in desmodium that performs this glycosylation by searching for C-glycosyltransferase activity on substrates in the biosynthetic pathway in protein extracts of root tissue. We will purify the protein by following this activity using standard protein purification techniques and characterise its structure by determining its amino acid sequence. This sequence will allow us to search the genomes of edible crop legumes in an effort to find this protein and so breed edible crop legumes that, when intercropped, also prevent striga from parastising maize. In addition, the desmodium gene itself, which generates the C-glycosyltransferase protein in the plant, provides a target for genetic modification of an edible crop legume that will prevent striga parasitizing maize. This work will provide the first elucidation of how a valuable weed suppression mechanism can be utilised and could provide the basis for attempts to control weeds in agriculture in other developing countries and potentially also in developed countries, such as the UK.

在撒哈拉以南大草原农业中，一项主要活动是种植玉米，作为一种自给自足的作物。农民缺乏资源，有一系列问题需要解决，特别是虫害(钻茎虫)和寄生杂草(Striga)造成的产量损失。这种害虫是本地和引进的飞蛾的毛虫，它们攻击玉米的茎，造成广泛的损害，甚至倒塌造成植株的损失。在控制害虫的工作过程中，通过间作驱虫植物和诱捕作物引诱成虫离开玉米，发现了一种间作，对稻纵卷叶蛾有显著的控制作用。这些来自Striga属的寄生杂草属于骁龙科，对该地区1亿多人的主要粮食作物构成了主要威胁。控制稻瘟的间作作物是牛饲用豆类作物，俗称豆类作物，在农场种植时，玉米与高粱等其他维持生计的谷类作物一对一间作时，寄生稻瘟得到控制，玉米产量可从远低于1吨/公顷提高到5吨/公顷以上。为了证明这种保护是基于万寿菊根系产生的化学物质，已经证明，这种保护作用可以通过将水传递到万寿菊的根上，然后进入含有荆棘和玉米种子的土壤中来实现。此外，当在有营养但没有土壤的水中(水培)种植金线莲时，水捕获了活性，然后可以转移到土壤中的斯特里加和玉米种子，并再次控制了寄生虫。研究了影响这一控制的水的化学成分，并将含量的不同部分相互分离。千里光种子萌发后，产生一个胚根(根)，发育成寄生玉米的附着器官。然而，一个特定的组分会对胚根的发育造成干扰，由此我们已经确定了一种有效的胚根抑制剂。该化合物的结构为二C-糖基黄酮，称为异沙夫苷。许多植物具有产生黄酮类的能力，然而产生异查夫苷所需的糖基化步骤是不寻常的。我们建议通过在根组织蛋白质提取液的生物合成途径中寻找底物上的C-糖基转移酶活性来鉴定执行这种糖基化的金线莲中的酶。我们将使用标准的蛋白质纯化技术通过跟踪这一活性来纯化蛋白质，并通过确定其氨基酸序列来表征其结构。这一序列将使我们能够搜索可食用豆类作物的基因组，努力找到这种蛋白质，从而培育出可食用作物豆类作物，当间作时，还可以防止Striga寄生玉米。此外，在植物中产生C-糖基转移酶蛋白的结缕草基因本身，为转基因一种可食用的豆类作物提供了一个靶标，这将防止Striga寄生玉米。这项工作将首次阐明如何利用一种有价值的杂草抑制机制，并可能为其他发展中国家以及英国等发达国家的农业杂草控制努力提供基础。