寄生植物ストライガのゲノム研究

在非洲，限制作物生产的最重要的经济因素包括稻瘟病菌和亚洲稻瘟病菌等，它们影响了高粱、谷子、玉米、甘蔗和豌豆的生产，每年造成高达10亿美元的损失，影响到1亿多农民。控制稻瘟的基本战略是防止它们的繁殖，摧毁它们的土壤种子库，并将它们的传播限制在新的未受感染的地区。为此，包括高粱在内的几种作物的栽培品种和野生近缘植物已经被鉴定出对稻瘟的抗性。在水稻上，日本晴是一种抗稻瘟病的品种。然而，耐药的分子机制还不是很清楚。在我们的研究中，我们对水杨酸和茉莉酸在水稻防御稻瘟病菌中的作用进行了深入的研究。我们发现茉莉酸(JA)和水杨酸(SA)的防御途径是I-…侵染后在水稻根部产生的量更多。利用JA和SA途径突变体，我们发现抑制JA的生物合成导致严重的Striga敏感性，只有用JA处理植物才能恢复。另一方面，缺乏水杨酸的水稻对稻瘟病具有抗性。抗性表型的特征是强烈诱导JA防御途径。在侵染Striga的水稻根中，我们发现一种名为OsWRKY45的基因高度表达。当我们敲除该基因时，这些植物对striga侵染高度敏感，并通过添加JA恢复了这种敏感性。这些结果突显了OsWRKY45在调节JA和SA防御途径对稻瘟病菌的抗性中的重要意义。据我们所知，这些数据首次揭示了使单子叶植物抵抗寄生的抗性机制，并揭示了防御途径串扰的几个以前未知的特征。了解JA和SA复杂相互作用所涉及的机制对于了解抗性的演变和开发成功解决农业寄生杂草问题的方法是必要的。较少

In Africa, the most economically important constraints to crop production include Striga species i. e., S. hermonthica and S. asiatica, among others, which affect the production of sorghum, millet, maize, sugarcane and cowpea resulting in losses of up to USD 1 billion annually affecting over 100 million farmers. The fundamental strategies to control Striga are to prevent their reproduction, to destroy their soil seed bank and to limit their spread to new uninfested areas. Towards this end, cultivars and wild relatives of several crop species including sorghum, which show resistance to Striga have been identified. In rice, it was found that Nipponbare, a japonica cultivar is resistant against Striga. However, the molecular mechanisms underlying resistance are not well understood. In our study, we conducted an in-depth characterization of the roles of SA and JA in rice defence against Striga hermonthica. We found out that jasmonic acid (JA) and salicylic acid (SA) defence pathways were i … More nduced in rice roots after infection. Using JA and SA pathway mutants, we found that inhibiting JA biosynthesis resulted in severe Striga susceptibility only recovered by treating plants with JA. On the other hand, SA-deficient rice were resistant against Striga. The resistance phenotype was characterized by a strong induction of the JA defence pathway. In the Striga-infected rice roots, we found that a gene called OsWRKY45 was highly expressed. When we knocked down this gene, the plants were highly susceptible to Striga infection and the susceptibility was recovered by addition of JA. These results highlighted the significance of OsWRKY45 in regulating both the JA and SA defence pathways in resistance against Striga parasitism. These data offer to our knowledge, the first insight into the resistance mechanisms that enable monocots to resist Striga parasitism and have revealed several previously unknown characteristics of defence pathway crosstalk. Knowledge of the mechanisms involved in the complex JA and SA interactions are necessary to understand the evolution of resistance and the development of successful solutions to parasitic weed problems in agriculture. Less