DISSERTATION RESEARCH: Does Herbivory Signal Plants to Increase Nitrogen Uptake and Bolster Nitrogen and Starch Storage?

当植物受到食叶食草动物的攻击时，它们必须应对叶片组织的损失，叶片组织保存着植物丰富的营养物质，对于从阳光中获取能量以供生长至关重要。植物可以将它们的一些能量和营养储存在更坚硬的组织中，比如许多草食动物不容易吃的茎和根。淀粉和蛋白质是植物中最常见的贮藏化合物。在最近的研究中使用放射性碳，使得研究活植物中的分配过程成为可能。一项这样的研究表明，植物可能会增加储藏量以应对草食。茉莉酸(JA)是一种重要的信号分子，参与植物对食草动物攻击的识别，增加了向杨树和杨树幼树下部茎和根运输的放射性碳量。这里提出的研究将确定茉莉酸和昆虫食草性是否导致茎和根中储存化合物的增加，以及杨树和杨树根对养分的吸收增加。将使用对植物重要的元素(碳-11、氮-13)的放射性同位素在活植物中研究短期过程。将使用稳定同位素(碳-13、氮-15)和化学分析来检查储存化合物的长期积累情况。在食草动物开始咀嚼叶片后，氮素吸收增加，碳和氮储存化合物的积累增加，这表明植物可以调整自己的新陈代谢，以最大限度地提高它们在叶片损失和伤害中生存的能力，并改善它们的再生长。这项响应食草动物信号的存储调节的开创性研究对于了解植物如何进化来应对食草动物是必要的。此外，更好地了解植物如何耐受损害可能会影响商业农业和林业实践，并可能为操纵植物以改善生存和生长提供洞察力。

When plants are attacked by leaf-chewing herbivores, they must cope with the loss of leaf tissues, which hold an abundance of the plant's nutrients and are important for capturing energy from sunlight for growth. Plants can store some of their energy and nutrients in tougher tissues, such as stems and roots that many herbivores cannot eat as readily. Starch and proteins are the most common storage compounds in plants. The use of radioactive carbon in recent research has allowed the study of allocation processes in living plants. One such study indicates that plants might increase storage in response to herbivory. An important signal molecule, jasmonic acid (JA), involved in plant recognition of herbivore attack increased the amount of radioactive carbon transported to the lower stem and roots in poplar and aspen tree saplings. The research proposed here will determine whether JA and insect herbivory cause increases in storage compounds in the stem and roots and increased nutrient intake by the roots of poplars and aspens. Short-term processes will be studied in living plants using radioactive isotopes of elements important to plants (carbon-11, nitrogen-13). The longer-term build-up of storage compounds will be examined using stable isotopes (carbon-13, nitrogen-15) and chemical analysis. Increased nitrogen uptake and increased build-up of carbon and nitrogen storage compounds following the initiation of herbivore leaf-chewing would indicate that plants can adjust their metabolism to maximize their ability to survive leaf loss and damage and to improve their re-growth. This pioneering research of storage regulation in response to herbivore signals will be necessary to understand how plants have evolved to cope with herbivory. Moreover, an improved understanding of how plants tolerate damage may influence commercial agricultural and forestry practices, and could generate insights for manipulating plants to improve survival and growth.