Department of Genetics, Institute for Plant Biotechnology, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa.
Department of Genetics, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa.
Planta. 2018 Aug;248(2):477-488. doi: 10.1007/s00425-018-2916-8. Epub 2018 May 17.
Transcriptomic analysis indicates that the bacterial signalling molecule lumichrome enhances plant growth through a combination of enhanced cell division and cell enlargement, and possibly enhances photosynthesis. Lumichrome (7,8 dimethylalloxazine), a novel multitrophic signal molecule produced by Sinorhizobium meliloti bacteria, has previously been shown to elicit growth promotion in different plant species (Phillips et al. in Proc Natl Acad Sci USA 96:12275-12280, https://doi.org/10.1073/pnas.96.22.12275 , 1999). However, the molecular mechanisms that underlie this plant growth promotion remain obscure. Global transcript profiling using RNA-seq suggests that lumichrome enhances growth by inducing genes impacting on turgor driven growth and mitotic cell cycle that ensures the integration of cell division and expansion of developing leaves. The abundance of XTH9 and XPA4 transcripts was attributed to improved mediation of cell-wall loosening to allow turgor-driven cell enlargement. Mitotic CYCD3.3, CYCA1.1, SP1L3, RSW7 and PDF1 transcripts were increased in lumichrome-treated Arabidopsis thaliana plants, suggesting enhanced growth was underpinned by increased cell differentiation and expansion with a consequential increase in biomass. Synergistic ethylene-auxin cross-talk was also observed through reciprocal over-expression of ACO1 and SAUR54, in which ethylene activates the auxin signalling pathway and regulates Arabidopsis growth by both stimulating auxin biosynthesis and modulating the auxin transport machinery to the leaves. Decreased transcription of jasmonate biosynthesis and responsive-related transcripts (LOX2; LOX3; LOX6; JAL34; JR1) might contribute towards suppression of the negative effects of methyl jasmonate (MeJa) such as chlorophyll loss and decreases in RuBisCO and photosynthesis. This work contributes towards a deeper understanding of how lumichrome enhances plant growth and development.
转录组分析表明，细菌信号分子尿卟啉通过增强细胞分裂和细胞扩大的组合来增强植物生长，并可能增强光合作用。尿卟啉（7,8-二甲基黄嘌呤）是一种新型的多营养信号分子，由 Sinorhizobium meliloti 细菌产生，先前已被证明可促进不同植物物种的生长（Phillips 等人在 Proc Natl Acad Sci USA 96:12275-12280，https://doi.org/10.1073/pnas.96.22.12275，1999）。然而，这种植物生长促进的分子机制仍然不清楚。使用 RNA-seq 的全局转录谱分析表明，尿卟啉通过诱导影响膨压驱动生长和有丝分裂细胞周期的基因来促进生长，从而确保细胞分裂和发育叶片的扩张的整合。XTH9 和 XPA4 转录物的丰度归因于改善了细胞壁松弛的介导，以允许膨压驱动的细胞扩大。在尿卟啉处理的拟南芥植物中，有丝分裂 CYCD3.3、CYCA1.1、SP1L3、RSW7 和 PDF1 转录物增加，表明增强的生长是通过增加细胞分化和扩张以及随之而来的生物量增加来支撑的。还观察到协同的乙烯-生长素交叉对话，通过 ACO1 和 SAUR54 的相互过表达，其中乙烯通过刺激生长素生物合成和调节生长素运输机制到叶片来激活生长素信号通路并调节拟南芥生长。茉莉酸生物合成和响应相关转录物（LOX2；LOX3；LOX6；JAL34；JR1）的转录减少可能有助于抑制甲基茉莉酸（MeJa）的负效应，如叶绿素损失和 RuBisCO 及光合作用的减少。这项工作有助于更深入地了解尿卟啉如何增强植物的生长和发育。
