A Downside to Disease Resistance in Arabidopsis: The Trouble with LOV

本研究的总体目的是了解植物病害易感性的生理基础。为了实现这一目标，模式植物拟南芥的一种疾病正在被研究，因为它的基因简单。这种疾病是由一个单一的显性宿主基因控制的，由维多利亚锥虫真菌引起，其毒性取决于一种叫做维多利亚菌素的“毒素”的产生。如果产生维多利的分离株遇到携带易感基因的植物，就会发生疾病。在所有其他情况下，如缺乏维多利素的产生，或缺乏易感基因的植物，不会发生疾病。由于易感性完全依赖于单个基因，因此了解该基因的功能应该有助于了解植物的疾病易感性。在拟南芥中，易感性是由一种名为LOV的基因赋予的，该基因编码一种CC-NBS-LRR型蛋白。具有讽刺意味的是，这种蛋白质唯一已知的功能是赋予疾病抵抗力。尽管如此，LOV控制着疾病的易感性。LOV的鉴定为植物抗性基因功能提供了一个完全不同的视角，并表明抗性的诱导可能需要生理变化，从而增加植物对病原体的脆弱性。将要开展的工作将通过一系列方法来调查这种可能性，这些方法将确定已知的抗性反应是否会导致疾病易感性，反之，LOV所赋予的反应是否会导致疾病抗性。我们预计这两种结果都有可能出现。这一努力的更广泛影响将纳入本科和研究生水平的教育。例如，植物的反应将被用作本科课程中实验室练习的基础。此外，这项研究将为研究生和博士后研究人员提供经验，他们的成果将通过出版物和研讨会传播。

The overall objective of this research is to understand the physiological basis of plant disease susceptibility. To accomplish this, a disease in the model plant, Arabidopsis thaliana is being investigated because of its genetic simplicity. The disease is conditioned by a single dominant host gene and is caused by the fungus Cochliobolus victoriae whose virulence depends on the production of a "toxin" called victorin. If a victorin-producing isolate encounters a plant carrying the gene for susceptibility, disease occurs. In all other cases, such as a lack of victorin production, or a plant lacking the susceptibility gene, disease does not occur. Because susceptibility is completely dependent on a single gene, understanding the function of that gene should contribute to understanding plant disease susceptibility. In Arabidopsis, susceptibility is conferred by a gene called LOV (for locus orchestrating victorin sensitivity) which encodes a CC-NBS-LRR type protein. Ironically, the only known function for this type of protein is in conferring disease resistance. Nonetheless, LOV conditions disease susceptibility. The identification of LOV presents a fundamentally different perspective on plant resistance gene function and implies that the induction of resistance can entail physiological changes that actually increase a plant's vulnerability to pathogens. The work to be conducted will investigate this possibility through a combination of approaches that will determine whether known resistance responses can lead to disease susceptibility and conversely, whether the response conferred by LOV can confer disease resistance. We anticipate that both outcomes are likely. The broader impacts of this effort will be integrated into both undergraduate and graduate level education. For example, the plant response will be used as the basis for a laboratory exercise in an undergraduate course. Also, the research will provide experiences for graduate and postdoctoral researchers whose results will be disseminated through publications and seminars.