DISSERTATION RESEARCH: Influence of Herbivory and Plant Age on Induced Resistance of the Black Mustard, Brassica nigra

这项提案探讨了植物如何通过增加新组织的防御来应对食叶昆虫的伤害。黑芥菜在自然界中有两种主要的破坏叶子的昆虫：芥菜跳甲和卷心菜白蝴蝶的毛虫。一项初步研究表明，由毛虫取食使黑芥菜新叶上的保护性毛发密度增加了一倍，而跳蚤甲虫取食则没有。这项新的实验测试了叶毛密度翻了一番是否能保护新叶免受任何一种草食动物的后续损害，并将表明更大的初始损害是否会刺激植物对新叶的更大保护。这些实验还将测试植物的自我保护能力是否会随着年龄的增长而下降。这项研究有三个重要方面。首先，研究人员主要集中在植物化学对虫害的反应上，而往往忽略了叶毛。其次，关于自然界中是否存在破坏叶子的昆虫之间的竞争，人们知之甚少。这项研究可能证明昆虫之间的竞争是通过它们对植物抗性的影响而间接发生的。第三，这项研究可能表明，作物科学家如何操纵农作物的内在防御，以更有效地对抗虫害。

This proposal explores how plants respond to injury by leaf-feeding insects by increasing defenses in new tissue. The black mustard, Brassica nigra, has two principal leaf-damaging insects in nature: the mustard flea beetle and caterpillar of the cabbage white butterfly. A preliminary study showed that feeding by the caterpillar caused the black mustard to double the density of protective hairs on new leaves, whereas feeding by flea beetles did not. The new experiments test whether this doubling of leaf hair density protects new leaves from subsequent damage by either herbivore and will show whether greater initial damage stimulates even greater protection of new leaves by the plant. The experiments will also test whether a plant's ability to protect itself declines with age. There are three significant aspects to this research. First, researchers have primarily concentrated on responses of plant chemistry to insect damage and often ignored leaf hairs. Second, little is known about whether there is competition among leaf-damaging insects in nature. This research may demonstrate that competition between insects occurs indirectly through their effects on plant resistance. Third, the research may indicate how crop scientists can manipulate intrinsic defenses of agricultural crops to more effectively combat insect pests.