Dataset Information

Trichome Independent Resistance against Western Flower Thrips in Tomato.

ABSTRACT: Western flower thrips (WFT) are a major pest on many crops, including tomato. Thrips cause yield losses, not only through feeding damage, but also by the transmission of viruses of which the Tomato Spotted Wilt Virus is the most important one. In cultivated tomato, genetic diversity is extremely low, and all commercial lines are susceptible to WFT. Several wild relatives are WFT resistant and these resistances are based on glandular trichome-derived traits. Introgression of these traits in cultivated lines did not lead to WFT resistant commercial varieties so far. In this study, we investigated WFT resistance in cultivated tomato using a F2 population derived from a cross between a WFT susceptible and a WFT resistant cultivated tomato line. We discovered that this WFT resistance is independent of glandular trichome density or trichome-derived volatile profiles and is associated with three QTLs on chromosomes 4, 5 and 10. Foliar metabolic profiles of F3 families with low and high WFT feeding damage were clearly different. We identified α-tomatine and a phenolic compound as potential defensive compounds. Their causality and interaction need further investigation. Because this study is based on cultivated tomato lines, our findings can directly be used in nowadays breeding programs.

SUBMITTER: Bac-Molenaar JA

PROVIDER: S-EPMC6534821 | biostudies-other | 2019 May

REPOSITORIES: biostudies-other

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Trichome Independent Resistance against Western Flower Thrips in Tomato.

Bac-Molenaar Johanna A JA Mol Selena S Verlaan Maarten G MG van Elven Joke J Kim Hye Kyong HK Klinkhamer Peter G L PGL Leiss Kirsten A KA Vrieling Klaas K

Plant & cell physiology 20190501 5

Western flower thrips (WFT) are a major pest on many crops, including tomato. Thrips cause yield losses, not only through feeding damage, but also by the transmission of viruses of which the Tomato Spotted Wilt Virus is the most important one. In cultivated tomato, genetic diversity is extremely low, and all commercial lines are susceptible to WFT. Several wild relatives are WFT resistant and these resistances are based on glandular trichome-derived traits. Introgression of these traits in culti ...[more]

PMID: 30715458

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Project description:Western flower thrips (WFT) Frankliniella occidentalis (Pergande) is a key agricultural pest of cultivated tomatoes. Induced host plant resistance by activating jasmonic acid (JA) signaling pathway constitutes a promising method for WFT control. The phytotoxin coronatine (COR), produced by Pseudomonas syringae pv. tomato DC3000 (Pst), mimics the plant hormone JA-Isoleucine and can promote resistance against herbivorous arthropods. Here we determined the effect of Pst and COR on tomato resistance against WFT, induction of JA and salicylic acid (SA) associated defenses, and plant chemistry. Additionally, we investigated the presence of other components in Pst-derived and filtered culture medium, and their interactive effect with COR on tomato resistance to WFT. Our results showed that infiltration of COR or Pst reduced WFT feeding damage in tomato plants. COR and Pst induced the expression of JA-associated gene and protein marker. COR also induced expression of a SA-related responsive gene, although at much less magnitude. Activation of JA defenses in COR and Pst infiltrated plants did not affect density of type VI leaf trichomes, which are defenses reported to be induced by JA. An untargeted metabolomic analysis showed that both treatments induced strong changes in infiltrated leaves, but leaf responses to COR or Pst slightly differed. Application of the Pst-derived and filtered culture medium, containing COR but not viable Pst, also increased tomato resistance against WFT confirming that the induction of tomato defenses does not require a living Pst population to be present in the plant. Infiltration of tomato plants with low concentrations of COR in diluted Pst-derived and filtered culture medium reduced WFT feeding damage in a greater magnitude than infiltration with an equivalent amount of pure COR indicating that other elicitors are present in the medium. This was confirmed by the fact that the medium from a COR-mutant of Pst also strongly reduced silver damage. In conclusion, our results indicate that induction of JA defenses by COR, Pst infection, the medium of Pst and the medium of a Pst COR- mutant increased resistance against WFT. This was not mediated by the reinforcement of leaf trichome densities, but rather the induction of chemical defenses.

Project description:Understanding the mechanisms involved in host plant resistance opens the way for improved resistance breeding programs by using the traits involved as markers. Pest management is a major problem in cultivation of ornamentals. Gladiolus (Gladiolus hybridus L.) is an economically important ornamental in the Netherlands. Gladiolus is especially sensitive to attack by western flower thrips (Frankliniella occidentalis (Pergande) (Thysanoptera:Thripidae)). The objective of this study was, therefore, to investigate morphological and chemical markers for resistance breeding to western flower thrips in Gladiolus varieties. We measured thrips damage of 14 Gladiolus varieties in a whole-plant thrips bioassay and related this to morphological traits with a focus on papillae density. Moreover, we studied chemical host plant resistance to using an eco-metabolomic approach comparing the 1H NMR profiles of thrips resistant and susceptible varieties representing a broad range of papillae densities. Thrips damage varied strongly among varieties: the most susceptible variety showed 130 times more damage than the most resistant one. Varieties with low thrips damage had shorter mesophylls and epidermal cells, as well as a higher density of epicuticular papillae. All three traits related to thrips damage were highly correlated with each other. We observed a number of metabolites related to resistance against thrips: two unidentified triterpenoid saponins and the amino acids alanine and threonine. All these compounds were highly correlated amongst each other as well as to the density of papillae. These correlations suggest that papillae are involved in resistance to thrips by producing and/or storing compounds causing thrips resistance. Although it is not possible to distinguish the individual effects of morphological and chemical traits statistically, our results show that papillae density is an easy marker in Gladiolus-breeding programs targeted at increased resistance to thrips.

Project description: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.

Dataset Information

Trichome Independent Resistance against Western Flower Thrips in Tomato.

Publications

Trichome Independent Resistance against Western Flower Thrips in Tomato.

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