Malitsky Sergey, Blum Eyal, Less Hadar, Venger Ilya, Elbaz Moshe, Morin Shai, Eshed Yuval, Aharoni Asaph
Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel.
Plant Physiol. 2008 Dec;148(4):2021-49. doi: 10.1104/pp.108.124784. Epub 2008 Oct 1.
In this study, transcriptomics and metabolomics data were integrated in order to examine the regulation of glucosinolate (GS) biosynthesis in Arabidopsis (Arabidopsis thaliana) and its interface with pathways of primary metabolism. Our genetic material for analyses were transgenic plants overexpressing members of two clades of genes (ALTERED TRYPTOPHAN REGULATION1 [ATR1]-like and MYB28-like) that regulate the aliphatic and indole GS biosynthetic pathways (AGs and IGs, respectively). We show that activity of these regulators is not restricted to the metabolic space surrounding GS biosynthesis but is tightly linked to more distal metabolic networks of primary metabolism. This suggests that with similarity to the regulators we have investigated here, other factors controlling pathways of secondary metabolism might also control core pathways of central metabolism. The relatively broad view of transcripts and metabolites altered in transgenic plants overexpressing the different factors underlined novel links of GS metabolism to additional metabolic pathways, including those of jasmonic acid, folate, benzoic acid, and various phenylpropanoids. It also revealed transcriptional and metabolic hubs in the "distal" network of metabolic pathways supplying precursors to GS biosynthesis and that overexpression of the ATR1-like clade genes has a much broader effect on the metabolism of indolic compounds than described previously. While the reciprocal, negative cross talk between the methionine and tryptophan pathways that generate GSs in Arabidopsis has been suggested previously, we now show that it is not restricted to AGs and IGs but includes additional metabolites, such as the phytoalexin camalexin. Combining the profiling data of transgenic lines with gene expression correlation analysis allowed us to propose a model of how the balance in the metabolic network is maintained by the GS biosynthesis regulators. It appears that ATR1/MYB34 is an important mediator between the gene activities of the two clades. While it is very similar to the ATR1-like clade members in terms of downstream gene targets, its expression is highly correlated with that of the MYB28-like clade members. Finally, we used the unique transgenic plants obtained here to show that AGs are likely more potent deterrents of the whitefly Bemisia tabaci compared with IGs. The influence on insect behavior raises an important question for future investigation of the functional aspect of our initial finding, which pointed to enriched expression of the MYB28-like clade genes in the abaxial domain of the Arabidopsis leaf.
在本研究中,整合了转录组学和代谢组学数据,以研究拟南芥中硫代葡萄糖苷(GS)生物合成的调控及其与初级代谢途径的界面。我们用于分析的遗传材料是过表达两个基因分支(分别调控脂肪族和吲哚族GS生物合成途径的ALTERED TRYPTOPHAN REGULATION1 [ATR1] - 样和MYB28 - 样)成员的转基因植物。我们表明,这些调控因子的活性不仅限于GS生物合成周围的代谢空间,而是与初级代谢中更远端的代谢网络紧密相连。这表明,与我们在此研究的调控因子类似,其他控制次生代谢途径的因素也可能控制中心代谢的核心途径。对过表达不同因子的转基因植物中改变的转录本和代谢物的相对广泛观察强调了GS代谢与其他代谢途径(包括茉莉酸、叶酸、苯甲酸和各种苯丙烷类代谢途径)的新联系。它还揭示了在为GS生物合成提供前体的代谢途径“远端”网络中的转录和代谢枢纽,并且ATR1 - 样基因分支的过表达对吲哚类化合物代谢的影响比先前描述的要广泛得多。虽然先前已提出在拟南芥中产生GS的甲硫氨酸和色氨酸途径之间存在相互的负向串扰,但我们现在表明,这种串扰不仅限于脂肪族和吲哚族GS,还包括其他代谢物,如植保素camalexin。将转基因系的谱数据与基因表达相关性分析相结合,使我们能够提出一个模型,说明GS生物合成调控因子如何维持代谢网络中的平衡。似乎ATR1/MYB34是两个基因分支的基因活性之间的重要介导因子。虽然它在下游基因靶点方面与ATR1 - 样基因分支成员非常相似,但其表达与MYB28 - 样基因分支成员的表达高度相关。最后,我们利用在此获得的独特转基因植物表明,与吲哚族GS相比,脂肪族GS可能是烟粉虱更有效的威慑物。对昆虫行为的影响为未来研究我们最初发现的功能方面提出了一个重要问题,该发现指出MYB28 - 样基因分支在拟南芥叶片背面区域中表达富集。