Transcriptomic basis of genome by genome variation in a legume-rhizobia mutualism
Transcriptomic basis of genome by genome variation in a legume-rhizobia mutualism
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DOI：
10.1111/mec.14285
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发表时间：
2017-11-01
影响因子：
4.9
通讯作者：
Tiffin, Peter
中科院分区：
文献类型：
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作者：
Burghardt, Liana T.;Guhlin, Joseph;Tiffin, Peter
在豆科植物-根瘤菌共生关系中，每一方从另一方获得的利益取决于寄主和根瘤菌共生体的遗传同一性。为了在分子水平上深入了解基因组9在宿主上的相互作用程度，并确定导致这种变异的潜在机制，我们研究了与Ensifer meliloti或E. medicae共生体生长的四种基因型的苜蓿根瘤（发生共生的植物器官）内的宿主基因表达。这些寄主- 9共生体组合在根瘤和生物量表型上表现出显著的差异。同样，组合在转录组上也存在差异：宿主、共生体和宿主9共生体分别影响了结核中表达的约27000个宿主基因的70%、27%和21%的表达。表达水平最高的基因通常在宿主和/或共生菌株之间有所不同，包括调节氧可用性的豆血红蛋白和参与共生分化和结核生存能力的数百种富半胱氨酸（NCR）肽。具有寄主9共生体依赖性表达的基因富集于伙伴间资源交换相关功能（硫酸盐/铁/氨基酸运输和二羧酸盐/氨基酸合成）。这些富集表明了互惠主义货币的东道国控制机制。与其他寄主相比，大部分分子研究使用的参考基因组truncatula菌株HM101 （A17）的转录组受共生体身份的影响较小。这些发现强调了在多种遗传环境下评估生态重要性状变异的分子基础的重要性，特别是那些涉及生物相互作用的性状。
In the legume-rhizobia mutualism, the benefit each partner derives from the other depends on the genetic identity of both host and rhizobial symbiont. To gain insight into the extent of genome 9 genome interactions on hosts at the molecular level and to identify potential mechanisms responsible for the variation, we examined host gene expression within nodules (the plant organ where the symbiosis occurs) of four genotypes of Medicago truncatula grown with either Ensifer meliloti or E. medicae symbionts. These host 9 symbiont combinations show significant variation in nodule and biomass phenotypes. Likewise, combinations differ in their transcriptomes: host, symbiont and host 9 symbiont affected the expression of 70%, 27% and 21%, respectively, of the approximately 27,000 host genes expressed in nodules. Genes with the highest levels of expression often varied between hosts and/or symbiont strain and include leghemoglobins that modulate oxygen availability and hundreds of Nodule Cysteine-Rich (NCR) peptides involved in symbiont differentiation and viability in nodules. Genes with host 9 symbiont-dependent expression were enriched for functions related to resource exchange between partners (sulphate/iron/amino acid transport and dicarboxylate/amino acid synthesis). These enrichments suggest mechanisms for host control of the currencies of the mutualism. The transcriptome of M. truncatula accession HM101 (A17), the reference genome used for most molecular research, was less affected by symbiont identity than the other hosts. These findings underscore the importance of assessing the molecular basis of variation in ecologically important traits, particularly those involved in biotic interactions, in multiple genetic contexts.