RUI: EPIGENETIC WEAPONS IN PLANT-HERBIVORE INTERACTIONS: SULFORAPHANE AS A NATURAL HISTONE DEACETYLASE INHIBITOR IN LEPIDOPTERAN PESTS

这个项目将研究一种新的“表观遗传武器”，十字花科植物部署对破坏性的害虫。表观遗传系统通过暂时打开或关闭染色体片段来调节数百个基因的表达，使得这些片段中的基因可以被激活或去激活。 这些系统指导正常的生长和发育，并使个人能够迅速应对不断变化的环境。 最近，已经观察到萝卜硫素，一种来自十字花科植物（例如，西兰花，花椰菜），破坏昆虫幼虫吃植物叶子时的表观遗传控制系统。因此，萝卜硫素可以作为一种针对害虫的表观遗传武器。这将代表一种新的植物防御类型，它有可能破坏昆虫的发育，从而保护农作物。 初步数据表明，萝卜硫素对害虫毛虫的有效性取决于剂量、温度和害虫种类。 多面手似乎最容易受到这种物质的影响。 相比之下，共同进化以这些植物为食的专业昆虫似乎通过某种未知的机制产生了部分抗性。 为了探索这种抗性机制，将研究三种经济上重要的害虫物种的幼虫发育，因为它们在一定温度范围内消耗不同剂量的萝卜硫素。 实验将确定这种物质对以下方面的影响：（1）幼虫的存活和发育，（2）成年蛾和蝴蝶的健康，（3）这些昆虫的表观遗传控制系统，以及（4）与重要代谢途径和过程相关的基因表达。 还将评估萝卜硫素引起的表观遗传变化可能持续存在，影响可能没有食用这种物质的后代的可能性。 该项目可能为保护作物提供新的方法，并提高我们对植物如何影响昆虫种群的理解。 它还将在三年内支持约20名本科生的多样化群体的教育，为这些学生在相关领域的研究生和专业工作做好准备。 十字花科植物产生萝卜硫素（SFN），一种核组蛋白脱乙酰酶（HDAC）的抑制剂，已被研究为潜在的药物和膳食补充剂。 在人类中，萝卜硫素的消耗会在几分钟内改变酶活性，DNA-组蛋白结合和基因表达。 然而，SFN在自然界中作为HDAC抑制剂，破坏食草昆虫的表观遗传机制的能力从未被探索过。 有人提出，植物可以利用SFN作为“表观遗传武器”。 初步数据表明，膳食SFN显着降低HDAC活性和减缓发展的军队蠕虫（甜菜夜蛾），有时影响第二代幼虫。 相反，甘蓝夜蛾（粉纹夜蛾）似乎对SFN有部分抗性。 为了进一步探索这一点，研究人员将确定SFN如何改变以这些植物为食的三种食草动物的第一代和第二代幼虫的发育，HDAC活性，组蛋白乙酰化和整体基因表达：Pieris raplum（卷心菜白色），Trichoplusia ni（卷心菜尺蠖），Spodoptera exigua（军虫）。 这些反应将在一定温度范围内进行检查。 RNA-seq将用于分析差异基因表达，将鉴定直向同源基因组，使用基因本体分类预测差异表达基因的推定功能，并将差异表达基因映射到代谢途径。拟议的实验将首次验证植物HDAC抑制剂可以干扰昆虫表观遗传机制的假设。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project will investigate a novel “epigenetic weapon” that cruciferous plants deploy against destructive insect pests. Epigenetic systems regulate the expression of hundreds of genes by temporarily opening or closing chromosomal segments so that the genes in these segments can be activated or de-activated. These systems direct normal growth and development and allow individuals to respond rapidly to changing environments. Recently, it has been observed that sulforaphane, a natural substance from cruciferous plants (e.g., broccoli, cauliflower), disrupts the epigenetic control systems of insect larvae while they eat plant leaves. Thus, sulforaphane may serve as an epigenetic weapon against pest insects. This would represent a new category of plant defense, one with the potential to sabotage insect development and thereby protect crop plants. Preliminary data indicate that the effectiveness of sulforaphane against pest caterpillars depends on the dosage, the temperature, and the pest species. Generalist feeders seem to be most susceptible to this substance. In contrast, specialist insects which co-evolved to feed upon these plants seem to have developed partial resistance, by some unknown mechanism. To explore this mechanism of resistance, the larval development of three economically important pest species will be examined as they consume various doses of sulforaphane over a range of temperatures. Experiments will determine the impacts of this substance on (1) larval survival and development, (2) the health of adult moths and butterflies, (3) the epigenetic control systems of these insects, and (4) the expression of genes associated with important metabolic pathways and processes. The possibility that the epigenetic changes induced by sulforaphane may linger, affecting future generations which may not have consumed this substance, will also be evaluated. This project may suggest new methods for protecting crop plants and improve our understanding how plants influence insect populations. It will also support the education of a diverse group of ~20 undergraduates over three years, preparing these students for graduate- and professional-level work in related fields. Cruciferous plants produce sulforaphane (SFN), an inhibitor of nuclear histone deacetylases (HDACs) which has been investigated as a potential drug and dietary supplement. In humans, sulforaphane consumption alters enzyme activity, DNA-histone binding, and gene expression within minutes. However, the ability of SFN to act as a HDAC inhibitor in nature, disrupting the epigenetic machinery of herbivorous insects, has never been explored. It is proposed that plants can employ SFN as an “epigenetic weapon”. Preliminary data demonstrate that dietary SFN dramatically reduces the HDAC activity and slows development of the army worm (Spodoptera exigua), sometimes affecting second-generation larvae. In contrast, the cabbage looper (Trichoplusia ni) seems to be partially resistant to SFN. To explore this further, the investigators will determine how SFN alters development, HDAC activity, histone acetylation, and global gene expression in 1st and 2nd generation larvae of three herbivores which feed on these plants: Pieris rapae (cabbage white), Trichoplusia ni (cabbage looper), Spodoptera exigua (army worm). These responses will be examined over a range of temperatures. RNA-seq will be used to analyze differential gene expression, orthologous gene groups will be identified, the putative function of differentially expressed genes will be predicted using gene ontology classifications, and differentially expressed genes will be mapped to metabolic pathways. The proposed experiments would, for the first time, test the hypothesis that plant HDAC inhibitors can interfere with the epigenetic machinery of insects. This would represent a new category of plant defense.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.