Division of Plant and Soil Sciences, Davis College of Agriculture, Natural Resources and Design, West Virginia University, 1194 Evansdale Drive, Morgantown, WV, 26506, USA.
J Chem Ecol. 2021 Feb;47(2):204-214. doi: 10.1007/s10886-021-01243-4. Epub 2021 Jan 14.
Secondary metabolites produced in glandular trichomes of tomato are involved in interactions with herbivores. In cultivated tomato (Solanum lycopersicum) glandular trichomes accumulate a blend of abundant monoterpenes and smaller amounts of a few sesquiterpenes. These mono- and sesquiterpenes are synthesized by three terpene synthases, TPS20 as well as TPS9 and TPS12, respectively. To study effects of these terpenes on performance and choice behavior of potato aphid (Macrosiphum euphorbiae), we utilized two tomato trichome mutants, hairless and odorless-2, that are differently affected in mono- and sesquiterpene production. Non-choice assays demonstrated that longevity and fecundity of M. euphorbiae were increased when kept on the trichome mutants. A principal component analysis of these aphid performance parameters and terpene production in the trichome mutants indicated that longevity and fecundity of M. euphorbiae were negatively correlated with production of the TPS12-derived sesquiterpenes β-caryophyllene and α-humulene. While we had previously shown that addition of pure β-caryophyllene/α-humulene to an artificial feeding diet affected M. euphorbiae apterae survivorship and feeding behavior, no such effects were observed here upon addition of a mixture of pure TPS20-derived monoterpenes. In olfactometer assays M. euphorbiae alates displayed differential choice behaviors towards the hairless and odorless-2 mutants suggesting a role of TPS20-derived monoterpenes in aphid attraction, which was further confirmed using a mixture of pure monoterpenes. Our analyses revealed contrasting roles of glandular trichome-derived terpenes in S. lycopersicum. While TPS12-derived sesquiterpenes contribute to host plant resistance against M. euphorbiae, TPS20-derived monoterpenes appear to be exploited as cue for host plant orientation by aphids.
番茄腺毛中产生的次生代谢产物参与了与草食动物的相互作用。在栽培番茄（Solanum lycopersicum）中，腺毛积累了丰富的单萜和少量几种倍半萜的混合物。这些单萜和倍半萜分别由三个萜烯合酶 TPS20、TPS9 和 TPS12 合成。为了研究这些萜烯对马铃薯蚜（Macrosiphum euphorbiae）的性能和选择行为的影响，我们利用了两种番茄毛突变体，hairless 和 odorless-2，它们在单萜和倍半萜的产生方面受到不同的影响。非选择试验表明，当马铃薯蚜被放置在毛突变体上时，其寿命和繁殖力增加。对这些蚜虫性能参数和毛突变体中萜烯产生的主成分分析表明，马铃薯蚜的寿命和繁殖力与 TPS12 衍生的倍半萜 β-石竹烯和 α-葎草烯的产生呈负相关。虽然我们之前已经表明，在人工饲养饲料中添加纯 β-石竹烯/α-葎草烯会影响马铃薯蚜无翅蚜的存活率和取食行为，但在这里添加纯 TPS20 衍生的单萜混合物时，没有观察到这种影响。在嗅觉计试验中，有翅蚜对 hairless 和 odorless-2 突变体表现出不同的选择行为，这表明 TPS20 衍生的单萜在蚜虫吸引中起作用，这一作用进一步通过使用纯单萜混合物得到证实。我们的分析揭示了番茄中腺毛衍生萜烯的不同作用。虽然 TPS12 衍生的倍半萜有助于番茄抵抗马铃薯蚜，但 TPS20 衍生的单萜似乎被蚜虫用作宿主植物定向的线索。
