Engineering Canola Oil With Altered Fatty Acid Composition

在经济上重要的农艺性状中，脂肪酸 (FA)油菜籽作物的组成是最有可能被 通过分子育种进行改良。 在这份提案中，我们描述了 这些实验将使我们能够设计出一种菜籽油， 亚麻酸（ALA）含量较低， 成分，除了营养质量较低， 导致酸败和风味不稳定， 自动氧化 为了实现这一变化， ALA的形成需要被隔离。 然而，由于基因 编码一种难以纯化的微粒体酶， 替代传统的生物化学方法基因 必须寻求隔离。 我们打算用一种强大的基因 方法，转座子标签，分离相应的基因。 小型模式植物拟南芥是一种遗传上更简单的 油菜籽的亲戚。 我们建议分离fad3基因， 在拟南芥中负责ALA的形成，作为第一个 朝着改变卡诺拉的脂肪酸组成迈出了一步。 我们 将使用链霉素耐药性试验（SPT）目视检测 玉米转座子激活子（Ac）在 拟南芥。从SPT：：Ac基因体细胞切除Ac产生 萌发于不同生长期的幼苗的白色子叶上出现绿色斑点 链霉素和吉兰霉素切除产生绿色回复突变体 在相同的试验中， 许多绿色回复突变体携带 转置的Ac元素。 在那里，SPT：：Ac系统允许我们 基因转位事件 通过选择绿色回复突变体， 在携带SPT：：Ac基因的植物的后代中， 从fad3，我们应该能够识别标记的fad3突变， 通过与Ac的同源性克隆它们。 来自卡诺拉的类似基因 可以通过与拟南芥基因的同源性分离， 随后被工程化以抑制内源性 fad3基因重新引入卡诺拉油菜。

Among the economically important agronomic traits, the fatty acid (FA) composition of oilseed crops is one of the most likely to be modified by molecular breeding. In this proposal, we described experiments that will enable us to engineer a canola (rapeseed) oil with a lower content of linolenic acid (ALA), an undesirable component that, in addition to being of lower nutritional quality, causes rancidity and flavor instability due to its tendency to auto-oxidize. To effect this change the gene responsible for the formation of ALA needs to be isolated. However, since the gene encodes a microsomal enzyme that is difficult to purify, an alternative to the conventional biochemical approach to gene isolation must be sought. We intend to use a powerful genetic approach, transposon tagging, to isolate the corresponding gene. The small model plant Arabidopsis thaliana is a genetically simpler relative of rapeseed. We propose to isolate the fad3 gene, responsible for the formation of ALA in Arabidopsis, as a first step towards the modification of the FA composition in canola. We will use a streptomycin resistance assay (SPT) to visually detect transposition of the maize transposon Activator (Ac) in Arabidopsis. Somatic excision of Ac from an SPT:: Ac gene produces green spots on the white cotyledons of seedlings germinated on streptomycin and germinal excision results in green revertant seedlings in the same assay. Many of the green revertants carry a transposed Ac element. There, the SPT:: Ac system allows us to for germinal transposition events. By selecting green revertants from among the progeny of plants that carry an SPT:: Ac gene only 5 cM from fad3, we should be able to identify tagged fad3 mutations and to clone them by homology to Ac. The analogous gene from canola can be isolated by homology to the Arabidopsis gene and subsequently engineered to suppress the action of the endogenous fad3 genes when reintroduced into canola.