Lignin engineering in field-grown poplar trees affects the endosphere bacterial microbiome
Lignin engineering in field-grown poplar trees affects the endosphere bacterial microbiome
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DOI：
10.1073/pnas.1523264113
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发表时间：
2016-02-23
影响因子：
11.1
通讯作者：
Vangronsveld, Jaco
中科院分区：
文献类型：
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作者：
Beckers, Bram;De Beeck, Michiel Op;Vangronsveld, Jaco
肉桂酰辅酶A还原酶(Ccr)是木质素生物合成途径的核心酶，是降低木质素水平和提高木质纤维生物质商业可行性的一个很有前途的生物技术目标。然而，Ccr基因的沉默导致一般木质素途径和单酚类木质素途径的通量发生相当大的变化，最终导致木质部中各种可提取酚类化合物的积累。在这里，我们评估了田间生长的、Ccr下调调控的杨树对细菌根际微生物群和内层微生物群(即根、茎和叶中存在的微生物群)的寄主基因型的影响。通过选择性分离和富集酚碳源(如阿魏酸)从所有植物隔间中分离出植物伴生细菌，这些碳源在Ccr缺失的杨树中上调表达。细菌内圈微生物群对Ccr缺陷型杨树有很高的响应能力，与WT树相比具有明显不同的代谢能力和相关的群落结构。相反，Ccr缺陷型和WT型杨树根际微生物群落具有高度重叠的细菌群落结构和代谢能力。我们通过植物基因组的微小遗传变异证明了寄主基因对植物微生物组的调节作用。因此，需要考虑这些相互作用，以了解植物代谢途径工程的全部后果，以及它与环境和预期的遗传改良的关系。
Cinnamoyl-CoA reductase (CCR), an enzyme central to the lignin bio-synthetic pathway, represents a promising biotechnological target to reduce lignin levels and to improve the commercial viability of lignocellulosic biomass. However, silencing of the CCR gene results in considerable flux changes of the general and monolignol-specific lignin pathways, ultimately leading to the accumulation of various extractable phenolic compounds in the xylem. Here, we evaluated host genotype-dependent effects of field-grown, CCR-down-regulated poplar trees (Populus tremula x Populus alba) on the bacterial rhizosphere microbiome and the endosphere microbiome, namely the microbiota present in roots, stems, and leaves. Plant-associated bacteria were isolated from all plant compartments by selective isolation and enrichment techniques with specific phenolic carbon sources (such as ferulic acid) that are up-regulated in CCR-deficient poplar trees. The bacterial microbiomes present in the endosphere were highly responsive to the CCR-deficient poplar genotype with remarkably different metabolic capacities and associated community structures compared with the WT trees. In contrast, the rhizosphere microbiome of CCR-deficient and WT poplar trees featured highly overlapping bacterial community structures and metabolic capacities. We demonstrate the host genotype modulation of the plant microbiome by minute genetic variations in the plant genome. Hence, these interactions need to be taken into consideration to understand the full consequences of plant metabolic pathway engineering and its relation with the environment and the intended genetic improvement.