Local adaptation is associated with zinc tolerance in Pseudomonas endophytes of the metal-hyperaccumulator plant Noccaea caerulescens
Local adaptation is associated with zinc tolerance in Pseudomonas endophytes of the metal-hyperaccumulator plant Noccaea caerulescens
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DOI：
10.1098/rspb.2016.0648
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发表时间：
2016-05-11
影响因子：
4.7
通讯作者：
Preston, G. M.
中科院分区：
文献类型：
--
作者：
Fones, H. N.;McCurrach, H.;Preston, G. M.
金属超积累植物被认为利用金属来防御害虫和病原体，为研究植物与病原体的共同进化提供了独特的背景。此前，我们证明了在超积累植物蓝藻的叶片中发现的高浓度锌可以提供对细菌病原体的保护，在基于金属的防御和病原体诱导的防御之间存在潜在的权衡。我们推测，蓝藻基于锌的防御和病原菌对锌的耐受性之间的进化军备竞赛可能推动了超积累表型的发展。在这里，我们研究了细菌对蓝藻叶片富锌环境进行局部适应的可能性，并表明从前矿场污染环境中采集的叶片中含有的内生菌比人工创建的超积累种群中的植物对锌的耐受性更强。人工种群植物中锌浓度的实验操作影响了恢复的内生真菌对锌的耐性。在实验室实验中，只有从自然种群植物中分离出来的内生细菌才能在任何一种蓝藻植物中生长到高种群密度。这些发现表明，长期与锌超积累植物共存导致内生细菌对其叶片内的环境进行局部适应。
Metal-hyperaccumulating plants, which are hypothesized to use metals for defence against pests and pathogens, provide a unique context in which to study plant-pathogen coevolution. Previously, we demonstrated that the high concentrations of zinc found in leaves of the hyperaccumulator Noccaea caerulescens provide protection against bacterial pathogens, with a potential trade-off between metal-based and pathogen-induced defences. We speculated that an evolutionary arms race between zinc-based defences in N. caerulescens and zinc tolerance in pathogens might have driven the development of the hyperaccumulation phenotype. Here, we investigate the possibility of local adaptation by bacteria to the zinc-rich environment of N. caerulescens leaves and show that leaves sampled from the contaminated surroundings of a former mine site harboured endophytes with greater zinc tolerance than those within plants of an artificially created hyperaccumulating population. Experimental manipulation of zinc concentrations in plants of this artificial population influenced the zinc tolerance of recovered endophytes. In laboratory experiments, only endophytic bacteria isolated from plants of the natural population were able to grow to high population densities in any N. caerulescens plants. These findings suggest that long-term coexistence with zinc-hyperaccumulating plants leads to local adaptation by endophytic bacteria to the environment within their leaves.