Acylsugar Research Articles

The frequency and chemical phenotype of neighboring plants determine the effects of intraspecific plant diversity.

Associational effects, whereby plants influence the biotic interactions of their neighbors, are an important component of plant-insect interactions. Plant chemistry has been hypothesized to mediate these interactions. The role of chemistry in associational effects, however, has been unclear in part because the diversity of plant chemistry makes it difficult to tease apart the importance and roles of particular classes of compounds. We examined the chemical ecology of associational effects using backcross-bred plants of the Solanum pennellii introgression lines. We used eight genotypes from the introgression line system to establish 14 unique neighborhood treatments that maximized differences in acyl sugars, proteinase inhibitor, and terpene chemical diversity. We found that the chemical traits of the neighboring plant, rather than simply the number of introgression lines within a neighborhood, influenced insect abundance on focal plants. Furthermore, within-chemical class diversity had contrasting effects on herbivore and predator abundances, and depended on the frequency of neighboring plant chemotypes. Notably, we found insect mobility-flying versus crawling-played a key role in insect response to phytochemistry. We highlight that the frequency and chemical phenotype of plant neighbors underlie associational effects and suggest this may be an important mechanism in maintaining intraspecific phytochemical variation within plant populations.

Inhibition of multidrug-resistant MCF-7 breast cancer cells with combinations of clinical drugs and resin glycosides from Operculina hamiltonii

The jalap roots, Operculina hamiltonii D.F. Austin & Staples (Convolvulaceae), are extensively commercialized as a depurative and laxative remedy in traditional medicine of the north and northeast regions of Brazil. The purification by recycling HPLC and structure elucidation of three new acyl sugars or resin glycosides are described here from a commercial product made of powdered roots. Three macrocyclic structures of a tetrasaccharide of (11S)-hydroxyhexadecanoic acid, operculinic acid C (1), the undescribed hamiltonins II and III (3 and 4), in addition to the known batatinoside III (5), presented a diastereoisomeric relationship as one residue of n-dodecanoic acid esterified the oligosaccharide core on a different position in each compound. Furthermore, hamiltonin IV (6) was characterized as an ester-type homodimer of acylated operculinic acid C with the same substitution pattern identified in hamiltonins II (3) and III (4) for each of the dimer subunits. All the isolated resin glycosides did not display any intrinsic cytotoxicity (IC50 > 25 μM). However, a combination of the individual isolated compounds 3–6 (1–50 μM) demonstrated an enhancement of cytotoxic effects with sublethal doses of vinblastine and podophyllotoxin (0.003 μM) in multidrug-resistant breast carcinoma epithelial cells (MCF-7/Vin).

Resistance to whitefly mediated by the Mi gene, acylsugars, and zingiberene in tomato

This study aimed to quantify and compare the effects of Mi gene, high leaf levels of acylsugars (AA), and zingiberene (ZGB) individually and in combination, regarding resistance of tomato lines to Bemisia argentifolii. The experiment included 21 genotypes selected simultaneously for high AA and ZGB content, cloned through rooting of axillary shoots with homogeneous sizes, and seven control lines produced from seeds, including 2 genotypes rich in AA (TOM-687 and TOM-688), two genotypes rich in ZGB (TOM-703 and TOM-704), and three lines with low levels of allelochemicals (cv. Santa Clara, TOM-584, and TOM-684), where the TOM-684 line carried the Mi gene. The experiment was conducted in a greenhouse using a randomized complete block design, comprising 28 treatments with 4 replications and 1 plant per plot. The AA and ZGB-rich lines showed higher resistance compared to the other control lines with low levels of allelochemicals, but the TOM-684 control line carrying the Mi gene was more resistant than the non-carriers ('Santa Clara' and TOM-584). The level of resistance conferred by ZGB was similar to that presented by AA. Both ZGB and AA provided higher levels of resistance compared to the Mi gene. The clones selected for both ZGB and AA simultaneously exhibited lower numbers of eggs and nymphs compared to the susceptible controls and were more resistant than the TOM-684 treatment. Overall, the clones even outperformed the lines rich in only one of the allelochemicals, demonstrating a synergistic effect between AA and ZGB for resistance when combined in the same tomato line.

Dwarf Tomato Plants Allow for Managing Agronomic Yield Gains with Fruit Quality and Pest Resistance through Backcrossing

Increased productivity, nutritional quality, and pest resistance have been primary breeding goals. However, managing such increases in a genotype is challenging. In this context, gene introgression using dwarf plants is an alternative; however, there are no dwarf Santa Cruz tomato varieties for direct use in breeding programs. Therefore, the objective of this study was to improve fruit quality and pest resistance through successive backcrossing of dwarf Santa Cruz tomato populations with agronomic potential. Six and 13 dwarf tomato populations obtained from the first and second backcrossing, respectively, the donor parent, and the commercial cultivar ‘Santa Clara’ as the check, totalling 21 treatments, were evaluated. Univariate analysis and computational intelligence were used to evaluate the best genotypes. All agronomic variables showed significant and progressive increases after the first and second backcrossing. The highlighted BC2 populations were Sci#16.1-2, Sci#25.1,1-2, Sci#25.1,2-2, Sci#3.1,1-2, Sci#3.1,2-2, Sci#8.3,1-2, and Sci#8.3,2-2, with significant increases in mean fruit weight, pulp thickness, fruit length and diameter, and acyl sugar content. The selected BC2 populations can be used as male parents to obtain normal hybrids to achieve increased productivity, nutritional quality, and a broader spectrum of pest resistance owing to the presence of acyl sugars in the leaflets.

Role of trichomes in plant defence – A crop specific review

Trichomes have long been investigated as an initial line of defence against insect herbivores. The structure, categorization and diversity of trichomes in flowering plants, as well as their mechanisms of action against abiotic and biotic stresses, are discussed. Plant-herbivore interactions are complicated interactions involving intricate networks of chemicals, signals and tactics to overcome each other's defences. To gain nutrients from host plants, herbivores employ a variety of feeding techniques. Plants respond by activating several defence mechanisms. Context of this review is based over the research on herbivore-trichome interactions and how trichomes are involved in both direct and indirect plant defences. Importance of trichome exudates like terpenes, acyl sugars, phenyl propanoid derivatives, methyl ketones, flavonoids and defensive proteins have been discussed. In our study, we emphasized on the relevance of trichomes as a reliable indicator of plant defence and how it is involved in defence responses of some economically important crops. Finally, we suggest several promising new study avenues for future work on trichomes and trichome-mediated responses.

The Genetic Complexity of Type-IV Trichome Development Reveals the Steps towards an Insect-Resistant Tomato.

The leaves of the wild tomato Solanum galapagense harbor type-IV glandular trichomes (GT) that produce high levels of acylsugars (AS), conferring insect resistance. Conversely, domesticated tomatoes (S. lycopersicum) lack type-IV trichomes on the leaves of mature plants, preventing high AS production, thus rendering the plants more vulnerable to insect predation. We hypothesized that cultivated tomatoes engineered to harbor type-IV trichomes on the leaves of adult plants could be insect-resistant. We introgressed the genetic determinants controlling type-IV trichome development from S. galapagense into cv. Micro-Tom (MT) and created a line named “Galapagos-enhanced trichomes” (MT-Get). Mapping-by-sequencing revealed that five chromosomal regions of S. galapagense were present in MT-Get. Further genetic mapping showed that S. galapagense alleles in chromosomes 1, 2, and 3 were sufficient for the presence of type-IV trichomes on adult organs but at lower densities. Metabolic and gene expression analyses demonstrated that type-IV trichome density was not accompanied by the AS production and exudation in MT-Get. Although the plants produce a significant amount of acylsugars, those are still not enough to make them resistant to whiteflies. We demonstrate that type-IV glandular trichome development is insufficient for high AS accumulation. The results from our study provided additional insights into the steps necessary for breeding an insect-resistant tomato.

Tuta absoluta (Meyrick) resistance in tomato (Solanum lycopersicum L.) accessions and species

We performed this study to evaluate the resistance of 36 wild and cultivated tomato accessions to Tuta absoluta (Meyrick) under greenhouse conditions in fall 2017. Phenotypically, accessions of species S. chilense, S. habrochaites, S. cheesmaniae, S. chmielewskii, and S. galapagense showed significantly fewer plant damages, i.e. less sensitivity. We re-evaluated nine resistant accessions of various species in vitro compared to susceptible “Moneymaker” by choice and no-choice tests to describe the level and mechanism of resistance. Ches-3 (S. cheesmaniae AusTRCF312323), Gal-1 (S. galapagense LA317), Chil—2 (S. chilense LA1967), Chil-3 (S. chilense LA1969); and Hab-7 (S. habrochaites CGN 15391) showed antixenosis (reduced oviposition and larval penetration) and antibiosis resistances (inhibited larval and pupal development and lack of new offspring). In addition, resistance was related to increased leaf content of zingiberene and acyl sugars, particularly in CGN15391. Resistant accessions Ches-3, Gal-1, Chm-2 (S. chmielewskii LA1327), Chil-2 and Hab-7 shared some polymorphic bands in SDS-PAGE analysis, indicating their similarity in gene expression and metabolic activity under T. absoluta infestation conditions. Hab-7 is considered more resistant than other resistant accessions because its low plant damage, high leaf content of zingiberene and acyl sugars, and coding of all resistance-related proteins.

Insights on solanaceous resistance against tomato leafminer (Tuta absoluta), with emphasis on chemical compounds useful in integrated pest management

For integrated pest management (IPM) and organic farming, breeding resistant varieties is one of the most eco-friendly approaches, that goes along botanicals and other different cultural practices, as the use of companion plants. Among the many pest species that invaded the whole world in the last decades, one of the most frightening is the tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), a devastating pest of cultivated tomato worldwide. Tomato is one of the most important agricultural commodities, including the main mean of subsistence in many countries from Africa and middle East. As chemical pesticides failed to control de pest spread and led to many reports of resistant populations, alternative methods for tomato leafminer management must be quickly developed. Many of such alternatives count on a wide range of chemical compounds. The chemical compounds most often responsible for “constitutive resistance”, synthetized by tomato are methyl-ketones (2-tridecanone), sesquiterpenes (zingiberene), and acyl sugars (acylglucose and acylsucrose) while the chemical compounds produced by other plants, used as isolated substances or mixtures, which have antifeedant, growth inhibiting, repellent, and insecticide effects, are azadirachtin, carvacrol, cinnamaldehyde, citronellal, eugenol, linalool, nicotine, pyrethrin, rotenone, thujone, thymol, α-terpineol, 1.8-cineol, etc. Many of them are already commercially available but their efficacy and use differ widely. Therefore, a deeper understanding of the resistance mechanism of solanaceous species related to chemical compounds and substances important for IPM plans developed against T. absoluta is required by the breeding programs.

Tomato trichomes are deadly hurdles limiting the establishment of Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae)

Amblyseius swirskii is a predatory mite widely used for the control of very important pest species, such as whiteflies and thrips, in organic farming and conventional agriculture. However, this species cannot establish on tomato crops, probably due to the toxic effects of plant trichomes and their exudates. We evaluated tomato plants for effects on: a) A. swirskii preference mediated by plant volatiles, b) A. swirskii development, predation capacity and reproductive performance, c) the dispersal and survival of mites as affected by stem trichomes, and d) mite survival as a function of secondary metabolites secreted by tomato trichomes. The results showed that A. swirskii mites which gained experience foraging on tomato plants, tend to avoid them. The survival of A. swirskii eggs and juveniles on tomato leaves was not different from that on sweet pepper. However, adult survival was significantly lower when tested on whole plants. This was ostensibly due to the impact of trichomes and their secondary metabolites that are abundant on the stems and which negatively impacted mite dispersal on the plant. Among the secondary metabolites detected in tomato trichomes, the strongest negative effects were associated with acyl sugars. Acyl sugars were highly toxic to the mites and also, physically accumulated on their bodies after walking on tomato stems. Altogether, our results reveal why A. swirskii is not an efficient biocontrol agent on tomato crops.

Chemical diversity rather than cultivar diversity predicts natural enemy control of herbivore pests.

Cultivar mixtures have been studied for decades as a means for pest suppression. The literature, however, shows a large variability in outcomes, suggesting that we are unable to create mixtures that consistently suppress insect pests and attract natural enemies. A key gap in our understanding of how cultivar mixtures influence pest control is that few studies have examined the plant traits or mechanisms by which cultivar diversity affects pests and their interactions with natural enemies. The diversity of plant chemistry in a cultivar mixture is one trait dimension that is likely influential for insect ecology because chemical traits alter how predators and herbivores forage and interact. To understand how plant chemical diversity influences herbivores and their interactions with predators, we fully crossed predator presence or absence with monocultures, bicultures, and tricultures of three chemotypes of tomato that differed in odor diversity (terpenes) or surface chemistry (acyl sugars) in a caged field experiment. We found that the direct effects of plant chemotype diversity on herbivore performance were strongest in bicultures and depended on herbivore sex, and these effects typically acted through growth rather than survival. The effects of chemotype diversity on top-down pest suppression by natural enemies differed between classes of chemical diversity. Odor diversity (terpenes) interfered with the ability of predators to hunt effectively, whereas diversity in surface chemistry (acyl sugars) did not. Our results suggest that phytochemical diversity can contribute to pest suppression in agroecosystems, but that implementing it will require engineering cultivar mixtures using trait-based approaches that account for the biology of the pests and natural enemies in the system.

Disentangling dimensions of phytochemical diversity: alpha and beta have contrasting effects on an insect herbivore.

Phytochemical diversity is comprised of two main dimensions-the average (alpha) within-plant neighbors or the difference (beta) in the composition of chemicals between plant neighbors. Research, however, has primarily examined the consequences of phytochemical diversity on herbivore performance through a single dimension, even though diversity is multidimensional. Furthermore, the ecological role of phytochemical diversity is not well understood because each of these dimensions exhibits unique biological effects on herbivore performance. Therefore, it has been difficult to tease apart the relative importance of alpha and beta chemical diversities on plant-herbivore interactions. We experimentally manipulated alpha and beta diversities along a chemical gradient to disentangle the relative effects of these dimensions on the performance of a mobile generalist herbivore, Trichoplusia ni (Hübner), using 16 genotypes from the Solanum pennellii introgression lines. First, we found contrasting effects of alpha and beta diversities on herbivore performance. Second, when comparing diversity across and within chemical classes, herbivore performance was reduced when plant neighbors had greater diversity within chemical classes that are biologically inhibiting at higher quantities (i.e., quantitative defenses such as phenolics and acyl sugars). However, herbivore performance was enhanced when plant neighbors had higher levels of chemical classes that are biologically toxic (i.e., qualitative defenses such as alkaloids). Finally, herbivores performed better on plant dicultures compared to monocultures, and performance was positively associated with plant dicultures only when there were high levels of average alpha diversity within plant neighbors. Our results suggest T. ni generalist caterpillars do better when plant neighbors are chemically different because differences provide options for them to choose or to switch between plants to balance chemical uptake. Overall, herbivores interact with a large diversity of plant chemicals at multiple scales, and our results indicate that not all chemical diversity is equal: specific dimensions of phytochemical diversity have unique effects on the dynamics of herbivore performance.

Pennelliisides A-C, 2,3,4-Trisubstituted Acyl Glucoses Isolated from Solanum pennellii.

Solanum species accumulate a variety of secondary metabolites in their trichomes, and it is well known that acyl sugars are specialized metabolites secreted by the trichomes. However, very few reports provide detailed information on the chemical structure of polyacylated glucose derivatives, due to the α and β isomerization that can occur at the C-1 position. In this study, a strategy was established to isolate polyacylated glucose derivatives. According to the developed strategy, hydroxy groups were derivatized to a benzyloxy group using TriBOT. After isolation of the compounds in pure form and deprotection of the benzyloxy group, the chemical structures of pennelliisides A-C were determined as 2,3,4-O-triisobutyryl-d-glucose, 3-O-(8-methylnonanoyl)-2,4-O-diisobutyryl-d-glucose, and 3-O-decanoyl-2,4-O-diisobutyryl-d-glucose, respectively. Structural elucidation was performed using spectroscopic techniques, including 1D and 2D NMR, FD-MS, and GC-MS. It was also found that the fatty acid moiety contributes to the allelopathic properties of the isolated compounds.

Effects of Water Deficit and Heat Stress on Nicotiana langsdorffii Metabolomic Pattern Modified by Insertion of rolD Gene from Agrobacterium rhizogenes.

Abiotic stresses are major factors that negatively affect plant growth and productivity. Plants have developed complex strategies to ensure their survival and reproduction under adverse conditions, activating mechanisms that involve changes at different metabolic levels. In order to select stress-resistant species, research has focused on molecular studies and genetic engineering, showing promising results. In this work, the insertion of the rolD gene from Agrobacterium rhizogenes into Nicotiana langsdorffii plants is investigated, in order to assess the potential of this genetic modification towards mitigating water and heat stresses. Different approaches were combined: a high-throughput metabolomics and ionomics study was performed, together with the determination of important plant phytohormones. The aim was to identify the influence of abiotic stresses on plants and to highlight the effects of the rolD genetic modification on plant stress response. The most relevant compounds for each kind of stress were identified, belonging mainly to the classes of lipids, acyl sugars, glycosides, and amino acid derivatives. Water stress (WS) determined a decrease of elements and secondary metabolites, while amino acids and their derivatives increased, proving to be key molecules in this type of stress. RolD plants exposed to high temperature stress (HS) presented higher dry weight levels than controls, as well as increased amounts of K and adenosine and lower levels of damage-associated metabolites, suggesting the increased resistance of rolD-modified plants toward HS.

The reaction of tomato genotypes to whitefly-transmitted ToYVSV influenced by allelochemicals and the genes Mi, Ty-1, Ty-2, and Ty-3/Ty-4

Forty-eight tomato genotypes, differing in their genotypic constitution (genes Ty and/or Mi + allelochemicals), were placed in a greenhouse with a high infestation of whiteflies, which had been previously fed with tomato plants infected by ToYVSV. The genotypes were kept in the same greenhouse throughout the entire experiment and were evaluated using a symptom rating scale. The estimated area under the disease progress curve (Area) and the mean scores from the last assessment were used to perform Dunnett's test with the susceptible and resistant controls. The genotypes were categorized according to their contents of acylsugar (AS) and zingiberene (ZB) and the presence or absence of the genes Mi, Ty-1, Ty-2, and Ty-3+Ty-4 to perform contrasts between groups and associate their effects to the different resistance levels observed. Alleles Mi and Ty-1 were more effective in promoting ToYVSV resistance in homozygozity than in heterozygosity. Lines homozygous for Ty-2 and Ty-3+Ty-4 showed significantly fewer symptoms than the resistant control, indicating that those alleles in homozygosity are the most effective in reducing ToYVSV symptoms. The results highlight the importance of pyramiding different resistance genes in adequate allelic dosages, in the process of lineages development aiming to obtain tomato genotypes with higher and more durable resistance to ToYVSV.

Patterns of inheritance of acylsugar acyl groups in selected interspecific hybrids of genus Nicotiana.

Glandular trichomes on the surface of Solanaceae species produce acyl sugars that are species-, and cultivar-specific. Acyl sugars are known to possess insecticidal, antibiotic, and hormone-like properties, and as such have great potential as a class of naturally occurring pesticides and antibiotics. The objective of this work was to analyze the acyl composition of acyl sugars in the leaf trichome exudate from selected Nicotiana species and to follow the inheritance of acyl content in their hybrids. Trichome exudates were collected, and the acyl profiles of acyl sugars were identified via GC-MS. The variations in acyl group inheritance in the hybrids (a single parent resemblance, missing, complementary, and novel groups) matched the patterns described in the literature for a variety of secondary metabolites. However, we did not find a complementation of major parental acyl groups. Instead, in some hybrids we observed a dynamic change in the proportions of acyl groups, distinguishing the acyl group profiles as novel. We observed paternal (i.e. N. tabacum cv. Turkish Samsun × N. benthamiana hybrids) and maternal (i.e. N. tabacum cv. Samsun-nn × N. otophora) inheritance patterns, novel acyl profiles (N. excelsior hybrids), and missing acyl groups (N. excelsiana). Selective inheritance of some acyl groups in the hybrids of N. benthamiana (4- and 5-methylheptanoic isomers) or N. alata (octanoate) was found. Suggestions are given to explain certain patterns of inheritance. The data presented here contribute to the body of knowledge about the effect of interspecific hybridization on the secondary metabolites by including acylsugar acyl groups that have not been studied previously.

Metabolomics approach based on NMR spectroscopy and multivariate data analysis to explore the interaction between the leafminer Tuta absoluta and tomato (Solanum lycopersicum).

Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is one of the most devastating and harmful pests of tomato (Solanum lycopersicum) crops causing up to 80-100% yield losses. A large arsenal of plant metabolites is induced by the leafminer feeding including defence compounds that could differ among varieties. To compare the metabolomic changes of different genotypes of tomato (tolerant "T", susceptible "S" and "F1" hybrid obtained between T and S) after exposition to T. absoluta. Nuclear magnetic resonance (NMR) spectroscopy followed by multivariate data analysis were performed to analyse the metabolic profiles of control and infested samples on three different tomato genotypes. Signals related to GABA (γ-aminobutyric acid) were relatively much higher in all infested samples compared to the non-infested plants used as control. Infested T genotype samples were the most abundant in organic acids, including fatty acids and acyl sugars, chlorogenic acid, neo-chlorogenic acid and feruloyl quinic acid, indicating a clear link between the exposure to leafminer. Results also showed an increase of trigonelline in all tomato varieties after exposition to T. absoluta. Metabolomics approach based on NMR spectroscopy followed by multivariate data analysis allowed for a detailed metabolite profile of plant defences, providing fundamental information for breeding programmes in plant crops.

Multivariate techniques in the determination of genetic diversity in pest-resistant mini tomato genotypes

ABSTRACT The objective of this study was to compare methods of multivariate analysis on the evaluation of genetic diversity of mini tomato and to identify promising genotypes with resistance to pests. The experiment was conducted at the Vegetable Experiment Station of the Universidade Federal de Uberlândia, Monte Carmelo campus, from April 2013 to November 2016. The experimental design was a randomized complete block design with 16 treatments and four replications totaling 64 plots, and each plot represented by five plants. Sixteen genotypes were characterized, 12 from the F2RC1 generation, obtained through the interspecific crossing between the wild access LA-716 (Solanum pennellii) and pre-commercial lines of mini tomato (UFU-73 and UFU-2) (Solanum lycopersicum) and the UFU-2 lines. The content of acyl sugar, the amount of glandular trichomes (types I, IV, VI and VII), twospotted spider mite and whitefly resistance were evaluated. We concluded that there exist genetic variability between the genotypes. The number of groups formed by the canonical variated analysis was higher (four groups) than that obtained by the Tocher method (three groups) and UPGMA (three groups), demonstrating a greater discrimination power. The Tocher and UPGMA methods were consistent in the analysis of the genetic divergence in pest resistant germplasm of tomato, with the acyl sugar content being the most important variable. Genotype UFU-73-F2RC1 # 11 is resistant to pest attack, while the other studied lines have intermediate resistance.

QTL mapping of insect resistance components of Solanum galapagense

Key messageQTLs for insect resistance parameters, trichome type IV development, and more than 200 non-volatile metabolites, including 76 acyl sugars, all co-locate at the end of Chromosome 2 of Solanum galapagense.Host plant resistance is gaining importance as more and more insecticides are being banned due to environmental concerns. In tomato, resistance towards insects is found in wild relatives and has been attributed to the presence of glandular trichomes and their specific phytochemical composition. In this paper, we describe the results from a large-scale QTL mapping of data from whitefly resistance tests, trichome phenotyping and a comprehensive metabolomics analysis in a recombinant inbred line population derived from a cross between the cultivated Solanum lycopersicum and the wild relative S. galapagense, which is resistant to a range of pest insects. One major QTL (Wf-1) was found to govern the resistance against two different whitefly species. This QTL co-localizes with QTLs for the presence of trichomes type IV and V, as well as all 76 acyl sugars detected and about 150 other non-volatile phytochemicals, including methyl esters of the flavonols myricetin and quercetin. Based on these results, we hypothesize that Wf-1 is regulating the formation of glandular trichome type IV on the leaf epidermis, enabling the production and accumulation of bioactive metabolites in this type of trichomes.

Genetic mapping identifies loci that influence tomato resistance against Colorado potato beetles

The Colorado potato beetle (CPB; Leptinotarsa decemlineata Say), the most economically important insect pest on potato (Solanum tuberosum L.), also feeds on other Solanaceae, including cultivated tomato (Solanum lycopersicum L.). We used tomato genetic mapping populations to investigate natural variation in CPB resistance. CPB bioassays with 74 tomato lines carrying introgressions of Solanum pennellii in S. lycopersicum cv. M82 identified introgressions from S. pennellii on chromosomes 1 and 6 conferring CPB susceptibility, whereas introgressions on chromosomes 1, 8 and 10 conferred higher resistance. Mapping of CPB resistance using 113 recombinant inbred lines derived from a cross between S. lycopersicum cv UC-204B and Solanum galapagense identified significant quantitative trait loci on chromosomes 6 and 8. In each case, the S. galapagense alleles were associated with lower leaf damage and reduced larval growth. Results of both genetic mapping approaches converged on the same region of chromosome 6, which may have important functions in tomato defense against CPB herbivory. Although genetic mapping identified quantitative trait loci encompassing known genes for tomato acyl sugar and glycoalkaloid biosynthesis, experiments with acyl sugar near-isogenic lines and transgenic GAME9 glycoalkaloid-deficient and overproducing lines showed no significant effect of these otherwise insect-defensive metabolites on CPB performance.

Dihydroresveratrol Type Dihydrostilbenoids: Chemical Diversity, Chemosystematics, and Bioactivity

Dihydrostilbenoids, a diverse class of natural products differing from stilbenoids by the missing double bond in the ethylene chain linking the aromatic moieties, have been reported from fungi, mosses, ferns, and flowering plants. Occurrence, structure, and bioactivity of naturally occurring dihydroresveratrol type dihydrostilbenoids are discussed in this review. A Reaxys database search for dihydroresveratrol derivatives with possible substitutions on all atoms, but excluding non-natural products and compounds featuring additional rings involving the ethyl connecting chain, was performed. Structures include simple dihydroresveratrol derivatives, compounds substituted with complex side chains composed of acyl moieties and sugars, and compounds containing polycyclic cores attached to dihydrostilbenoid units. Dihydrostilbenoids have a wide spectrum of bioactivities ranging from expectable antioxidant and anti-inflammatory activities to interesting neuroprotective and anticancer activity. The anticancer activity in particular is very pronounced for some plant-derived dihydrostilbenoids and makes them interesting lead compounds for drug development. Apart from some reports on dihydroresveratrol derivatives as phytoalexins against plant-pathogenic fungi, only very limited information is available on the ecological role of these compounds for the organisms producing them. Dihydrostilbenoids are a class of natural products possessing significant biological activities; their scattered but not ubiquitous occurrence throughout the kingdoms of plants and fungi is not easily explained. We are convinced that future studies will identify new sources of dihydrostilbenoids, and we hope that the present review will inspire such studies and will help in directing such efforts to suitable source organisms and towards promising bioactivities.