Zhang Dingpeng, Song Yeong Hun, Dai Ru, Lee Tong Geon, Kim Jeongim
Horticultural Sciences Department, University of Florida, Gainesville, FL, United States.
Gulf Coast Research and Education Center, University of Florida, Wimauma, FL, United States.
Front Plant Sci. 2020 Feb 5;11:17. doi: 10.3389/fpls.2020.00017. eCollection 2020.
Plants produce diverse secondary metabolites. Although each metabolite is made through its respective biosynthetic pathway, plants coordinate multiple biosynthetic pathways simultaneously. One example is an interaction between glucosinolate and phenylpropanoid pathways in . Glucosinolates are defense compounds made primarily from methionine and tryptophan, while phenylpropanoids are made from phenylalanine. Recent studies have shown that the accumulation of glucosinolate intermediate such as indole-3-acetaldoxime (IAOx) or its derivatives represses phenylpropanoid production the degradation of phenylalanine ammonia lyase (PAL) functioning at the entry point of the phenylpropanoid pathway. Given that IAOx is a precursor of other bioactive compounds other than glucosinolates and that the phenylpropanoid pathway is present in most plants, we hypothesized that this interaction is relevant to other species. is an oil crop and produces camalexin from IAOx. We enhanced IAOx production in Camelina by overexpressing which encodes an IAOx-producing enzyme. The overexpression of results in increased auxin content and its associated morphological phenotypes in Camelina but indole glucosinolates were not detected in Camelina wild type as well as the overexpression lines. However, phenylpropanoid contents were reduced in overexpression lines suggesting a link between aldoxime metabolism and phenylpropanoid production. Interestingly, the expression of was not affected in the overexpression lines although PAL activity was reduced. To test if PAL degradation is involved in the crosstalk, we identified F-box genes functioning in PAL degradation through a phylogenetic study. A total of 459 transcript models encoding kelch-motifs were identified from the database. Among them, the expression of involved in PAL degradation is up-regulated in the transgenic lines. Our results suggest a link between aldoxime metabolism and phenylpropanoid production in Camelina and that the molecular mechanism behind the crosstalk is conserved in Arabidopsis and Camelina.
植物产生多种次生代谢产物。尽管每种代谢产物都是通过其各自的生物合成途径生成的，但植物会同时协调多种生物合成途径。一个例子是拟南芥中硫代葡萄糖苷途径和苯丙烷类途径之间的相互作用。硫代葡萄糖苷是主要由蛋氨酸和色氨酸生成的防御化合物，而苯丙烷类则由苯丙氨酸生成。最近的研究表明，硫代葡萄糖苷中间体如吲哚 - 3 - 乙醛肟（IAOx）或其衍生物的积累会抑制苯丙烷类的生成，这是通过苯丙烷类途径起始点处发挥作用的苯丙氨酸解氨酶（PAL）的降解实现的。鉴于IAOx是除硫代葡萄糖苷之外其他生物活性化合物的前体，并且苯丙烷类途径存在于大多数植物中，我们推测这种相互作用与其他物种相关。荠蓝是一种油料作物，能从IAOx生成camalexin。我们通过过表达编码IAOx生成酶的基因来提高荠蓝中IAOx的产量。该基因的过表达导致荠蓝中生长素含量增加及其相关的形态表型，但在荠蓝野生型以及过表达株系中均未检测到吲哚硫代葡萄糖苷。然而，过表达株系中苯丙烷类含量降低，这表明乙醛肟代谢与苯丙烷类生成之间存在联系。有趣的是，尽管PAL活性降低，但该基因在过表达株系中的表达并未受到影响。为了测试PAL降解是否参与这种相互作用，我们通过系统发育研究鉴定了在PAL降解中起作用的F - box基因。从数据库中总共鉴定出459个编码kelch基序的转录本模型。其中，参与PAL降解的该基因在转基因株系中的表达上调。我们的结果表明荠蓝中乙醛肟代谢与苯丙烷类生成之间存在联系，并且这种相互作用背后的分子机制在拟南芥和荠蓝中是保守的。
