Efficient In Planta Detection and Dissection of De Novo Mutation Events in the Arabidopsis thaliana Disease Resistance Gene UNI
Efficient In Planta Detection and Dissection of De Novo Mutation Events in the Arabidopsis thaliana Disease Resistance Gene UNI
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DOI：
10.1093/pcp/pcw060
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发表时间：
2016-06-01
影响因子：
4.9
通讯作者：
Uchida, Naoyuki
中科院分区：
文献类型：
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作者：
Ogawa, Tomohiko;Mori, Akiko;Uchida, Naoyuki
植物具有由R基因编码的抗病(R)蛋白，每个R蛋白识别一个特定的致病因子(S)进行免疫。有趣的是，R基因的高度多态，这是进化过程中过去突变事件的痕迹，表明R基因迅速多样化。然而，由于缺乏使我们能够在实验可行的时间尺度上有效地监测从头开始的R基因突变的工具，尤其是在活的植物中，对于促进R基因快速变化的分子方面的了解很少。在这里，我们介绍了一种模型检测系统，它能够在一代中有效地检测拟南芥R基因UNI中的从头突变事件。UNI-1D突变体含有UNI基因的功能获得型等位基因。Uni-1D杂合子个体最初表现为矮秆，茎异常短小。然而，有趣的是，形态上正常的茎有时会自发地从Uni-1D植物中长出，而形态上恢复的组织携带着UNI基因的额外从头突变。令人惊讶的是，在极端条件下，几乎一半的受检人群出现了倒退现象。通过利用这一现象，我们证明了回复频率对DNA稳定性的各种波动非常敏感，这是UNI基因突变趋势的基础。我们还揭示了水杨酸途径和DNA损伤感受器途径的活性参与了逆转现象。因此，我们提供了一个实验上可行的模型工具来探索显著影响R基因突变现象的因素和条件。
Plants possess disease resistance (R) proteins encoded by R genes, and each R protein recognizes a specific pathogen factor(s) for immunity. Interestingly, a remarkably high degree of polymorphisms in R genes, which are traces of past mutation events during evolution, suggest the rapid diversification of R genes. However, little is known about molecular aspects that facilitate the rapid change of R genes because of the lack of tools that enable us to monitor de novo R gene mutations efficiently in an experimentally feasible time scale, especially in living plants. Here we introduce a model assay system that enables efficient in planta detection of de novo mutation events in the Arabidopsis thaliana R gene UNI in one generation. The uni-1D mutant harbors a gain-of-function allele of the UNI gene. uni-1D heterozygous individuals originally exhibit dwarfism with abnormally short stems. However, interestingly, morphologically normal stems sometimes emerge spontaneously from the uni-1D plants, and the morphologically reverted tissues carry additional de novo mutations in the UNI gene. Strikingly, under an extreme condition, almost half of the examined population shows the reversion phenomenon. By taking advantage of this phenomenon, we demonstrate that the reversion frequency is remarkably sensitive to a variety of fluctuations in DNA stability, underlying a mutable tendency of the UNI gene. We also reveal that activities of the salicylic acid pathway and DNA damage sensor pathway are involved in the reversion phenomenon. Thus, we provide an experimentally feasible model tool to explore factors and conditions that significantly affect the R gene mutation phenomenon.