Kliebenstein Daniel, Pedersen Deana, Barker Bridget, Mitchell-Olds Thomas
Department of Genetics and Evolution, Max-Planck Institute of Chemical Ecology, 07745 Jena, Germany.
Genetics. 2002 May;161(1):325-32. doi: 10.1093/genetics/161.1.325.
Evolutionary interactions among insect herbivores and plant chemical defenses have generated systems where plant compounds have opposing fitness consequences for host plants, depending on attack by various insect herbivores. This interplay complicates understanding of fitness costs and benefits of plant chemical defenses. We are studying the role of the glucosinolate-myrosinase chemical defense system in protecting Arabidopsis thaliana from specialist and generalist insect herbivory. We used two Arabidopsis recombinant inbred populations in which we had previously mapped QTL controlling variation in the glucosinolate-myrosinase system. In this study we mapped QTL controlling resistance to specialist (Plutella xylostella) and generalist (Trichoplusia ni) herbivores. We identified a number of QTL that are specific to one herbivore or the other, as well as a single QTL that controls resistance to both insects. Comparison of QTL for herbivory, glucosinolates, and myrosinase showed that T. ni herbivory is strongly deterred by higher glucosinolate levels, faster breakdown rates, and specific chemical structures. In contrast, P. xylostella herbivory is uncorrelated with variation in the glucosinolate-myrosinase system. This agrees with evolutionary theory stating that specialist insects may overcome host plant chemical defenses, whereas generalists will be sensitive to these same defenses.
植物化合物对宿主植物具有相反的适合度后果，这取决于各种植食性昆虫的攻击。这种相互作用使得理解植物化学防御的适合度成本和收益变得复杂。我们正在研究芥子油苷 - 黑芥子酶化学防御系统在保护拟南芥免受专食性和广食性昆虫取食方面的作用。我们使用了两个拟南芥重组自交群体，之前我们在其中定位了控制芥子油苷 - 黑芥子酶系统变异的数量性状位点（QTL）。在本研究中，我们定位了控制对专食性昆虫（小菜蛾）和广食性昆虫（粉纹夜蛾）抗性的QTL。我们鉴定出了一些仅对一种昆虫特异的QTL，以及一个控制对两种昆虫抗性的单一QTL。对昆虫取食、芥子油苷和黑芥子酶的QTL比较表明，较高的芥子油苷水平、更快的分解速率和特定的化学结构能强烈抑制粉纹夜蛾的取食。相比之下，小菜蛾的取食与芥子油苷 - 黑芥子酶系统的变异无关。这与进化理论相符，即专食性昆虫可能克服宿主植物的化学防御，而广食性昆虫会对这些相同的防御敏感。
