Kumar Pavan, Ortiz Erandi Vargas, Garrido Etzel, Poveda Katja, Jander Georg
Boyce Thompson Institute for Plant Research, 533 Tower Road, Ithaca, NY, 14853, USA.
Department of Entomology, Cornell University, Ithaca, NY, 14853, USA.
Oecologia. 2016 Sep;182(1):177-87. doi: 10.1007/s00442-016-3633-2. Epub 2016 May 4.
Plants mediate interactions between aboveground and belowground herbivores. Although effects of root herbivory on foliar herbivores have been documented in several plant species, interactions between tuber-feeding herbivores and foliar herbivores are rarely investigated. We report that localized tuber damage by Tecia solanivora (Guatemalan tuber moth) larvae reduced aboveground Spodoptera exigua (beet armyworm) and Spodoptera frugiperda (fall armyworm) performance on Solanum tuberosum (potato). Conversely, S. exigua leaf damage had no noticeable effect on belowground T. solanivora performance. Tuber infestation by T. solanivora induced systemic plant defenses and elevated resistance to aboveground herbivores. Lipoxygenase 3 (Lox3), which contributes to the synthesis of plant defense signaling molecules, had higher transcript abundance in T. solanivora-infested leaves and tubers than in equivalent control samples. Foliar expression of the hydroxycinnamoyl-CoA quinate hydroxycinnamoyl transferase (HQT) and 3-hydroxy-3-methylglutaryl CoA reductase I (HMGR1) genes, which are involved in chlorogenic acid and steroidal glycoalkaloid biosynthesis, respectively, also increased in response to tuber herbivory. Leaf metabolite profiling demonstrated the accumulation of unknown metabolites as well as the known potato defense compounds chlorogenic acid, α-solanine, and α-chaconine. When added to insect diet at concentrations similar to those found in potato leaves, chlorogenic acid, α-solanine, and α-chaconine all reduced S. exigua larval growth. Thus, despite the fact that tubers are a metabolic sink tissue, T. solanivora feeding elicits a systemic signal that induces aboveground resistance against S. exigua and S. frugiperda by increasing foliar abundance of defensive metabolites.
植物介导地上和地下食草动物之间的相互作用。尽管在几种植物物种中已记录到根部食草作用对叶部食草动物的影响，但块茎取食性食草动物与叶部食草动物之间的相互作用却很少被研究。我们报告称，茄实夜蛾（危地马拉块茎蛾）幼虫对块茎的局部损害降低了甜菜夜蛾和草地贪夜蛾在马铃薯上的地上部表现。相反，甜菜夜蛾对叶片的损害对地下的茄实夜蛾表现没有明显影响。茄实夜蛾对块茎的侵染诱导了植物的系统性防御，并增强了对地上部食草动物的抗性。参与植物防御信号分子合成的脂氧合酶3（Lox3）在被茄实夜蛾侵染的叶片和块茎中的转录丰度高于同等对照样本。分别参与绿原酸和甾体糖苷生物碱生物合成的羟基肉桂酰辅酶A奎宁酸羟基肉桂酰转移酶（HQT）和3-羟基-3-甲基戊二酰辅酶A还原酶I（HMGR1）基因的叶部表达也因块茎食草作用而增加。叶片代谢物谱分析表明，未知代谢物以及已知的马铃薯防御化合物绿原酸、α-茄碱和α-查茄碱有所积累。当以与马铃薯叶片中发现的浓度相似的浓度添加到昆虫饲料中时，绿原酸、α-茄碱和α-查茄碱均降低了甜菜夜蛾幼虫的生长。因此，尽管块茎是一种代谢库组织，但茄实夜蛾的取食引发了一种系统性信号，通过增加叶部防御性代谢物的丰度来诱导地上部对甜菜夜蛾和草地贪夜蛾的抗性。
