Collaborative Research: Plant Tolerance of Herbivory: A Test for Constraints on Adaptation

9815873魏实害虫对植物生产性能的影响一直是人们关注的问题。迄今为止，生态学家和农学家都把注意力集中在植物的抗攻击能力上，也就是说，植物阻止潜在敌人的能力。然而，昆虫的攻击很少是致命的，所以植物有机会采取第二种方式来应对敌人的攻击，恢复和再生。在遭受攻击后生存和繁荣的能力被称为宽容。与对抗性的遗传学和生态学研究进展相比，对植物恢复的了解甚少。这种知识空白阻碍了对整个植物防御系统的理解。研究耐受性的成本效益结构本身是很重要的，我们也需要通过理解耐受性来理解抗性的适应价值。抗性和耐受性的相互依存源于两个方面的考虑。首先，抗性和耐受性可能是多余的——如果植物可以完全从攻击中恢复过来，那么抵抗攻击就没有什么好处了。第二个考虑来自最优防御理论。人们普遍假设，抗性因素是昂贵的，因为用于抗性的资源也不能分配给生长。许多实验已经验证了这一假设，但结果好坏参半。最近的模型表明，抗性成本很难检测，因为它们被耐受性成本所掩盖。但由于对公差知之甚少，因此对公差成本知之甚少。因此，评估这些重要理论预测的依据很少。这些实验将利用野生芥菜品种Brassica campestris寻找耐受性成本，Brassica campestris是重要油料作物油菜的野生祖先。人工选择将被执行，以确定遗传权衡是否施加适应性成本，限制了油菜芽孢杆菌耐受落叶的能力。这个实验包括选择每一代都遭受严重损害的植物品系，从未遭受损害的品系，以及两者都遭受损害的品系。选择将通过兄弟姐妹选择。经过几代的选择，将通过在所有受损环境中生长来测量株系之间的耐受性差异。因此，这些实验将检验一些关于基因限制耐受性的主要假设，并将启动一项长期的努力，以确定有助于植物恢复的生理性状和潜在的遗传位点。此外，通过检查两种环境下的选择反应，这些实验将提供对表型可塑性选择约束的更普遍问题的见解。[参考译文]

9815873WeisHumans have long been concerned about the impact of insect pests on plant performance. To date ecologists and agronomists have concentrated on plant resistance to attack, that is, the plant's ability to deter potential enemies. However, insect attack is rarely fatal and so plants have the opportunity for a second way to deal with enemy attack, to recover and regrow. The ability to survive and prosper after attack is called tolerance. Compared to the research progress in understanding the genetics and ecology of resistance, very little is known about plant recovery. This knowledge void hampers understanding of the total plant defense system. Not only is it important to study the cost-benefit structure of tolerance in it own right, we also need to understand tolerance to understand the adaptive value of resistance. The interdependence of resistance and tolerance emerges from two considerations. First, resistance and tolerance can be redundant-if a plant can completely recover from attack, there is little profit in also resisting attack. The second consideration arises from optimal defense theory. It is widely hypothesized that resistance factors are costly since resources devoted to resistance cannot also be allocated to growth. Numerous experiments have tested this hypothesis, but with mixed results. Recent models suggest that resistance costs are hard to detect because they are obscured by tolerance costs. But because little is known about tolerance, little is known about tolerance costs. Thus, there is little basis for evaluating these important theoretical predictions. These experiments will look for tolerance costs using a wild mustard species, Brassica campestris, which is the wild progenitor of canola, the important oil seed crop. Artificial selection will be perform to determine if genetic trade-offs impose a fitness cost that constrains the ability of B. campestris to tolerate defoliation. This experiment involves selecting for performance in plant lines that experience sever damage every generation, lines that never experience damage, and lines that experience both. Selection will be by sib-selection. Following several generations of selection, tolerance differences among the lines will be measured by growing them across all damage environments. These experiments, thus, will test several major hypotheses about genetic constraints on tolerance, and will initiate a long-term effort to identify the physiological traits, and the underlying genetic loci, that contribute to plant recovery. In addition, by examining selection response across two environments, these experiments will offer insights on the more general problem of constraints on selection for phenotypic plasticity.H:\popbio\abstracts\fy1999\9815873 (Weis abstract)