Acylsugar amount and fatty acid profile differentially suppress oviposition by western flower thrips, Frankliniella occidentalis, on tomato and interspecific hybrid flowers

PLoS One. 2018 Jul 31;13(7):e0201583. doi: 10.1371/journal.pone.0201583. eCollection 2018.

Abstract

Tomatoes (Solanum lycopersicum L.) have been bred to exude higher amounts or different types of the specialized plant metabolites, acylsugars, from type IV trichomes. Acylsugars are known to deter several herbivorous insect pests, including the western flower thrips (WFT), Frankliniella occidentalis (Pergande); however, all previous studies investigated the effect of acylsugars on leaves, or acylsugar extracts obtained from leaves. In spite of the WFT predilection for flowers, there is a gap in knowledge about flower defenses against thrips damage. This is especially important in light of their capacity to acquire and inoculate viruses in the genus Orthotospovirus, such as Tomato spotted wilt orthotospovirus (TSWV), in flowers. Therefore, we turned our attention to assessing thrips oviposition differences on flowers of 14 entries, including 8 interspecific hybrids, 5 tomato lines bred for specific acylsugar-related characteristics (type IV trichome densities, acylsugar amount, sugar moiety and fatty acid profile), and a fresh market tomato hybrid, Mt. Spring, which only produces trace amounts of acylsugars. Our results show that the density of the acylsugar droplet bearing type IV trichomes is greatest on sepals, relative to other flower structures, and accordingly, WFT avoids oviposition on sepals in favor of trichome-sparse petals. In concordance with past studies, acylsugar amount was the most important acylsugar-related characteristic suppressing WFT oviposition. Certain acylsugar fatty acids, specifically i-C5, i-C9 and i-C11, were also significantly associated with changes in WFT oviposition. These results support continued breeding efforts to increase acylsugar amounts and explore modifications of fatty acid profile and their roles in deterring thrips oviposition. The finding that acylsugar production occurs and reduces thrips oviposition in tomato flowers will be important in efforts to use acylsugar-mediated resistance to reduce incidence of orthotospoviruses such as TSWV in tomato by deterring virus transmission and development of thrips vector populations in the crop.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Carbohydrate Metabolism / physiology
  • Chimera / metabolism*
  • Crosses, Genetic
  • Fatty Acids / metabolism*
  • Flowers* / metabolism
  • Herbivory
  • Insecta / drug effects
  • Oviposition / genetics
  • Pest Control, Biological
  • Plant Breeding*
  • Plant Diseases / genetics
  • Plant Diseases / prevention & control
  • Plants, Genetically Modified
  • Solanum lycopersicum* / genetics
  • Solanum lycopersicum* / metabolism
  • Sugars / analysis
  • Sugars / metabolism*
  • Sugars / pharmacology
  • Thysanoptera* / genetics
  • Thysanoptera* / metabolism

Substances

  • Fatty Acids
  • Sugars

Grants and funding

Funding for this research was provided by AFRI NIFA Coordinated Agricultural Project 2012-68004-20166. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.