Autoimmune response as a mechanism for a Dobzhansky-Muller-type incompatibility syndrome in plants.
Autoimmune response as a mechanism for a Dobzhansky-Muller-type incompatibility syndrome in plants.
复制标题
自身免疫反应是植物中Dobzhansky-Muller型不兼容综合征的机制。
DOI：
10.1371/journal.pbio.0050236
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发表时间：
2007-09
期刊：
影响因子：
9.8
通讯作者：
Weigel, Detlef
中科院分区：
文献类型：
--
作者：
Bomblies, Kirsten;Lempe, Janne;Epple, Petra;Warthmann, Norman;Lanz, Christa;Dangl, Jeffery L;Weigel, Detlef
基因间的上位性相互作用是进化的一个主要因素。杂种坏死是由上位性相互作用引起的有害表型的一个例子，在许多种内和种间植物杂种中观察到。大量的杂交坏死病例具有表型相似性，这表明在广泛的植物物种中存在共同的潜在机制。在这里，我们报告说，大约2%的种内杂交拟南芥产量F1后代表达坏死时，生长在典型的自然栖息地的条件下。我们发现，几个独立的情况下，上位相互作用，触发自身免疫样反应的结果。在至少一种情况下，当与第二基因座处的特定等位基因组合时，NB-LRR抗病性基因同源物的等位基因对于诱导杂交坏死是必要的且足够的。助理thaliana的案例提供了深入了解杂交坏死的分子原因，并作为一个模型，为进一步调查内和种间不相容性所造成的一个简单的上位相互作用。此外，我们的发现，植物免疫系统基因参与杂交坏死表明，选择压力有关的主机-病原体冲突可能会导致植物基因流障碍的演变。杂交将来自不同基因组的遗传物质结合在一起。有时候，新的基因组合对后代是有害的，即使这些基因在他们的父母身上是无害的，甚至是有益的。这种“遗传不相容性”在植物、动物和真菌的物种内和物种间的杂交中已经观察到，并且可能有助于维持种群或物种边界。我们已经调查了一个高度有害的遗传不相容性称为杂交坏死，是在许多植物类群观察。使用不同的野生株拟南芥作为一个模型，我们表明，杂交坏死往往与植物免疫系统的不适当激活有效的植物自身免疫。我们在一种菌株中发现了一种基因，当与另一种菌株的第二个基因座结合时会引发坏死。该基因的产物是NB-LRR蛋白，这是最常见类型的植物抗病蛋白。这一发现提出了一种可能性，即病原体施加的选择压力可以促进基因变异的快速进化，这些基因变异可能为亲本谱系提供益处，但可能对杂交后代造成严重问题。有时候，在父母中无害的基因在后代中结合时是有害的。在这里，一些基因参与杂交坏死植物已被确定。
Epistatic interactions between genes are a major factor in evolution. Hybrid necrosis is an example of a deleterious phenotype caused by epistatic interactions that is observed in many intra- and interspecific plant hybrids. A large number of hybrid necrosis cases share phenotypic similarities, suggesting a common underlying mechanism across a wide range of plant species. Here, we report that approximately 2% of intraspecific crosses in Arabidopsis thaliana yield F1 progeny that express necrosis when grown under conditions typical of their natural habitats. We show that several independent cases result from epistatic interactions that trigger autoimmune-like responses. In at least one case, an allele of an NB-LRR disease resistance gene homolog is both necessary and sufficient for the induction of hybrid necrosis, when combined with a specific allele at a second locus. The A. thaliana cases provide insights into the molecular causes of hybrid necrosis, and serve as a model for further investigation of intra- and interspecific incompatibilities caused by a simple epistatic interaction. Moreover, our finding that plant immune-system genes are involved in hybrid necrosis suggests that selective pressures related to host–pathogen conflict might cause the evolution of gene flow barriers in plants. Hybridization brings together genetic material from different genomes. Sometimes, the novel combinations of genes are deleterious in the offspring, even though the genes were innocuous, or even beneficial, in their parents. Such “genetic incompatibilities” have been observed in crosses within and between species in plants, animals, and fungi, and could contribute to the maintenance of population or species boundaries. We have investigated a highly deleterious genetic incompatibility called hybrid necrosis that is observed in many plant taxa. Using different wild strains of Arabidopsis thaliana as a model, we show that hybrid necrosis is often associated with inappropriate activation of the plant immune system—effectively plant autoimmunity. We identified a gene in one strain that triggers necrosis when combined with a second locus from another strain. The product of this gene is an NB-LRR protein, the most common type of plant disease resistance protein. This finding raises the possibility that selective pressure exerted by pathogens can promote rapid evolution of gene variants that might provide benefits to the parent lineage but can cause serious problems for hybrid progeny. Sometimes, genes that are innocuous in the parents are deleterious when combined in the offspring. Here, some genes involved in hybrid necrosis in plants have been identified.