The Alcohol and Epoxy Alcohol of Zingiberene, Produced in Trichomes of Wild Tomato, Are More Repellent to Spider Mites Than Zingiberene

Abstract

Allelochemicals that are present in trichome secretions of wild tomato species play a major role in mediating interactions with arthropods, often conferring a high level of resistance via antibiosis and antixenosis. Many accessions of the wild tomato relative, Solanum habrochaites (S.h), possess high levels of resistance to arthropods. The monocyclic sesquiterpene hydrocarbon, 7-epi-zingiberene, is a major defensive component found in trichome secretions of certain accessions of S.h. We have used LA2329, an S.h. accession, as a donor in a breeding program designed to introgress zingiberene into cultivated tomato. However, the composition of trichome secretions in our population of LA2329 is segregating, with some individuals producing mainly 7-epi-zingiberene in their secretions while others producing two additional, unidentified compounds in their trichome secretions. To investigate if these other compounds may also contribute to arthropod resistance, trichome secretions were collected from plants of S.h LA2329 grown under greenhouse conditions and then major compounds were isolated by silica gel column chromatography and tested for their ability to repel two spotted-spider mite (TSSM), Tetranychus urticae. Isolation and identification of allelochemicals were aided by use of gas chromatography/mass spectroscopy. The results revealed the presence of three predominate chromatographic peaks: 7-epi-zingiberene, 9-hydroxy zingiberene, and 9-hydroxy,10,11-epoxy-zingiberene. Results of testing isolated compounds for repellency to TSSM using bridge bioassays revealed that the repellent activities of 9hydroxy zingiberene and 9-hydroxy,10,11-epoxy-zingiberene were each significantly higher than that for 7-epi-zingiberene. These results support the idea that the degree of repellency may differ among plant allelochemicals and also emphasize the potential value of introgressing the presence of 9-hydroxy zingiberene and 9-hydroxy,10,11-epoxyzingiberene into cultivated tomato to enhance its arthropod resistance.

Natural variation in wild tomato trichomes; selecting metabolites that contribute to insect resistance using a random forest approach

“…The (semi-)volatile mono-and sesquiterpenes that are, at least predominantly, produced and stored in type-VI trichomes serve as another important class of metabolites implicated in the defence against pests [ 24 , 38 – 40 ]. The sesquiterpenes 7-epizingiberene and R-curcumene produced by wild tomato S. habrochaites PI127826 repel whiteflies and 7-epizingiberene alcohol derivatives have a repellent effect on the spider mite Tetranychus urticae [ 41 , 42 ]. Also, 2,3-dihydrofarnesoic acid from S. habrochaites accessions LA1363 and LA1927 act on spider mites as a repellent [ 43 ] and type-VI trichomes of S. habrochaites accession LA1777 produce a mixture of bergamotoic-and santanaloic acids that confers resistance against the tomato fruitworm ( Helicoverpa zea ) and the beet armyworm ( Spodoptera exigua) [ 44 ].…”

A single cytochrome P450 oxidase from Solanum habrochaites sequentially oxidizes 7‐epi‐zingiberene to derivatives toxic to whiteflies and various microorganisms

“…The bioactivity assays performed here point to a specific toxicity of 9H10epoZ, for which a clear, concentration-dependent effect was observed against B. tabaci ( Figure 6). A recent study also identified 9HZ and 9H10epoZ as potent repellents of spider mites, Tetranychus urticae (Dawood and Snyder, 2020), further confirming these compounds to be of potential relevance for resistance against arthropod Figure 6. Whitefly toxicity assays of (4R,7R)-zingiberene and its oxidized derivatives.…”

Prior Experience with Food Reward Influences the Behavioral Responses of the Honeybee Apis mellifera and the Bumblebee Bombus lantschouensis to Tomato Floral Scent

“…For example, bioassays have shown that naïve honeybees are attracted to apple floral scent [ 50 ]. However, many plants, including tomato, release repellent volatile organic compounds to defend against insect herbivores [ 51 , 52 , 53 ]. Plant defense against herbivores may show a trade-off with pollinator attraction [ 54 ].…”