生物(例如,重金属)和非生物胁迫(例如,昆虫攻击)会影响植物的化学防御,但是对植物防御同时发生的变化知之甚少。在这里,重金属镉(Cd)胁迫和昆虫食草胁迫对两种甘蓝型油菜品种直接和间接防御的影响,研究了低Cd品种Lvbao701和高Cd品种ChicaixinNo.4,对草食动物斜纹夜蛾进行了研究。尽管单独使用10mgkg-1Cd胁迫会抑制叶片次生代谢产物(总酚,黄酮类化合物),这也降低了斜纹镰刀菌对两种卷心菜的取食率和气味选择,特别是对于Lvbao701,通过增加叶片Cd含量和驱虫挥发性有机化合物(VOCs)(6-甲基-5-庚烯-2-酮,7,9-二叔丁基-1-氧杂螺(4,5)deca-6,9-二烯-2,8-二酮),减少可溶性糖和有吸引力的挥发性有机化合物(3-甲基-3-戊醇,2,5-己二酮,十四烷醛)。在2.5mgkg-1Cd和食草胁迫下,虽然叶片总酚和类黄酮显著增加,对两个品种卷心菜的采食率和气味选择增加,特别是赤菜新4号,表明卷心菜的化学防御受到抑制。因此,Cd胁迫单独提高了白菜的抗虫性,而食草胁迫削弱了Cd胁迫增强的白菜防御能力。低Cd品种Lvbao701的抗虫性强于赤菜新4号,表明在Cd污染土壤中施用Lvbao701不仅可以将Cd的传播降低到食物链中的更高水平,而且可以减少虫害的发生。
Biotic (e.g., heavy metal) and abiotic stress (e.g., insect attack) can affect plant chemical defense, but little is known about the changes in plant defense when they occur concurrently. Herein, the impacts of heavy metal cadmium (Cd) stress and insect herbivory stress on the direct and indirect defense of two cultivar cabbages of Brassica campestris, the low-Cd cultivar Lvbao701 and the high-Cd cultivar Chicaixin No.4, against the herbivore cutworm Spodoptera litura were investigated. Although 10 mg kg-1 Cd stress alone inhibited leaf secondary metabolites (total phenolics, flavonoids), it reduced the feeding rate and odor selection of S. litura towards both cultivar cabbages, especially for Lvbao701, by increasing leaf Cd content and repellent volatile organic compounds (VOCs) (6-methyl-5-hepten-2-one, 7,9-di-tert-butyl-1-oxaspiro (4,5)deca-6,9-diene-2,8-dione), and reducing soluble sugar and attractive VOCs (3-methyl-3-pentanol, 2,5-hexanedione, tetradecanal). Under 2.5 mg kg-1 Cd and herbivory stress, although leaf total phenolics and flavonoids increased significantly, the feeding rate and odor selection of S. litura towards both cultivar cabbages increased, especially for Chicaixin No.4, indicating that the chemical defense of cabbages was depressed. Therefore, Cd stress alone improved the insect resistance of cabbages, whereas herbivory stress weakened the enhanced cabbages defence by Cd stress. The low-Cd cultivar Lvbao701 presented stronger insect resistance than Chicaixin No.4, suggesting that Lvbao701 application in Cd-polluted soil can not only decrease Cd transmission to higher levels in the food chain but also reduce pest occurrence.