Dissertation Research: Evolution of Resistance, Tolerance and Species Interactions in a Brassica/Herbivore/Pathogen System

Weis0073558拟议的研究将使用温室和田间试验，野生芥菜和它的三种天敌，以确定1）抗性之间的遗传相关性，2）抗性之间的遗传相关性的敌人，3）耐受性和抗性之间的遗传相关性对特定的敌人，和4）天敌之间的生态相互作用。 研究的温室部分将提供确定遗传相关性所需的受控条件，田间部分将允许确定食草动物在田间的影响。 来自半同胞家庭的植物组将暴露于不同的处理，每个处理包括暴露于一种天敌或天敌的组合。 每个植物家族对其天敌的抗性和耐受性将从暴露于单一天敌的处理中确定。 将多个敌人攻击的影响与这些敌人中的每一个单独的影响进行比较，将确定是否存在生态相互作用。如果存在相互作用，那么一组天敌的影响将不同于它们独立影响的总和。这项研究将为了解植物防御天敌的遗传结构提供重要见解。 植物可以通过避免或最小化敌人的损害（抗性）或在损害发生后再生（耐受性）来科普天敌的攻击。 为了理解这些如何相互作用形成一个综合防御系统，需要了解两个潜在的限制：1）抗性或耐受性性状之间的遗传相关性和2）敌人之间的生态相互作用。 当抗性与耐受性在遗传上相关时，任何旨在提高其中一种的选择程序都会导致另一种的衰退。 当敌人相互作用时，它们对植物性能的影响可以是协同的，因此对一种敌人的抗性值可能无法单独预测对两种敌人的抗性值。 调查这两个限制可以帮助我们增加对草食动物多样性的植物防御的贡献的理解，并帮助构建面对多种有害害虫的作物的植物育种计划。

Weis0073558The proposed research will use greenhouse and field experiments with the wild mustard Brassica rapa and three of its natural enemies to determine 1) genetic correlations between resistance to enemies, 2) genetic correlations between tolerance of enemies, 3) genetic correlations between tolerance and resistance to a particular enemy, and 4) ecological interactions between natural enemies. A greenhouse component of the research will provide the controlled conditions necessary for determination of genetic correlations, and a field component will allow for determination of the impacts of herbivores in the field. Groups of plants from half-sib families will be exposed to different treatments, each consisting of exposure to one natural enemy or a combination of natural enemies. Resistance and tolerance of each plant family to their natural enemies will be determined from treatments exposed to single enemies. Comparison of the impact of attack by multiple enemies with the impact of each of those enemies alone will determine whether there are ecological interactions. If there are interactions, then the impact of a group of natural enemies will differ from the sum of their independent impacts.This research will provide important insights into the genetic structure of plant defense against their natural enemies. Plants can cope with attack by natural enemies by either avoiding or minimizing damage by the enemies (resistance) or by regrowing after damage has occurred (tolerance). In order to understand how these interact to form an integrated defense system, two potential constraints need to be understood: 1) genetic correlations between resistance or tolerance traits and 2) ecological interactions between enemies. When resistance is genetically correlated to tolerance, then any selection program to improve the one will cause the other to decline. When enemies interact, their effects on plant performance can be synergistic, thus the value of resistance to one enemy in isolation may not predict the total value of resistance to both. Investigating these two constraints can help increase our understanding of the contribution of plant defense on herbivore diversity, and aid in the structuring of plant breeding programs for crops that face multiple harmful pests.