Wild Chili Research Articles

Characterization of native Ya´ax ik chili pepper (Capsicum annuum L.) in the Yucatan Peninsula

Objective: To morphologically characterize the Ya´ax ik chili pepper: wild chili (Capsicum annuum), native variety from the Yucatan Peninsula. Design/methodology: Ya´ax ik chili pepper seeds were sown in 200-cavity polystyrene trays, and then the plants were placed in bags for hydroponics and were morphologically characterized using the Capsicum descriptor of the International Institute of Genetic Resources. Results: The plant showed 118 cm and 34.8 cm of height and ramification width and width of the intermediate plant, hanging white flowers and green fruits in the early stage and red at maturity with 7.42 and 2.32 cm length and width. Additionally, tolerance to the virus caused by whiteflies could be observed. Findings and conclusions: Plant with morphological characteristics susceptible to be genetically improved for its extensive farming, given the market acceptance of the fresh and dried fruit, supported by market prices.

Artisanal extraction of native chili seeds (Capsicum sp.)

Objective: To establish a methodology for the artisanal extraction and benefit of chili pepper seed from native and wild chili pepper varieties. Design/Methodology/Approach: From 2016 to 2019, nine chili pepper ecotypes were evaluated. The ecotypes include: habanero (Capsicum chinense Jacq); Ixcat ik, Bobo, Sweet, Maax, Bolita, Green (with red ripening), green (with yellow ripening), all of which belong to the Capsicum annuum; and Pico Paloma (Capsicum frutescens). The aim of the evaluations was to determine the morphological characteristics and the degree of genetic diversity. The extraction and exploitation method of the seeds was also evaluated. Cutting knives were used to extract the seeds. The seeds were dried in the open air, sheltered in closed and ventilated places. Both glass and plastic containers were used to store the seeds; the jars were lined with kitchen foil. Results: Two seed extraction procedures were used. Medium and large ecotype fruits were subject to circular and longitudinal cuts. For their part, small fruits were macerated. In order to dry the seeds, they were placed on metal trays or in perforated plastic baskets. The trays or bags were placed in ventilated and cool places (<40°C) for 8 to 10 days. Afterwards, they were stored at 5°C with low moisture and without light. Findings/Conclusions: The proposed methodology to obtain and exploit seeds in humid tropic conditions will support the conservation of the Capsicum resource, in the state of Campeche and the Yucatan Peninsula.

Spatial distribution and fluctuating populations of predatory mites (Mesostigmata: Phytoseiidae), phytophagous mites (Acari: Eriophyidae, Tetranychidae) and their relationships with wild chili pepper phenological stages in two Natural Protected Areas of Mexico

Ecological interactions between mites (predatory and phytophagous) and wild plants growing in undisturbed environments play a crucial role to understand their natural settlement, development and dispersion patterns. Pequin chili pepper, Capsicum annuum L. var. glabriusculum, is a low-cost natural resource for local communities living inside Natural Protected Areas (ANP) of Tamaulipas State in Mexico. The aims of this research work were: 1) determine the spatial distribution pattern of predatory and phytophagous mites, 2) determine the spatiotemporal association between predatory and phytophagous mites, and 3) determine the association among different mite species and some phenological stages of Pequin chili pepper. The most abundant phytophagous mites were Tetranychus merganser and Aculops lycpoersici, and the predatory species were Amblyseius similoides, Euseius mesembrinus and Metaseiulus (Metaseiulus) negundinis. Most mite species showed an aggregated distribution pattern according to the plant phenological stages. However, the distribution of mite species throughout time showed different types of aggregation. On the other hand, we found positive associations among A. lycopersici and T. merganser phytophagous mites with A. similoides, E. mesembrinus and M. (M.) negundinis predators mites. The association between plants and mite species were influenced by the phenological stages of Pequin chili pepper. This is an indication of the complexity among trophic-chain interactions that depend largely on the available resources and competition. These two factors serve as foundations for settlement, development and dispersion patterns of certain species.

Domestication of Chili Pepper Has Altered Fruit Traits Affecting the Oviposition and Feeding Behavior of the Pepper Weevil.

Simple SummaryThe pepper weevil is an economically important pest that causes major damage to fruits of chili pepper varieties selected for consumption. However, the impact of this pest on wild and ornamental peppers remains unknown. Therefore, we studied the effect of chili domestication on the feeding and oviposition behavior of pepper weevil when exposed to wild chili, ornamental varieties, and varieties used for consumption. More specifically, we examined how changes in fruit and flower size, fruit thickness, spiciness level, and fruit position as a result of the domestication of chili peppers affected their susceptibility to this specialist pepper pest. In addition, we recorded that fruits and flowers from wild and ornamental plants were less susceptible to pepper weevil attacks than those from chili varieties selected for consumption. Our results have important implications for chili pepper breeders and could guide the selection of new resistant varieties against this pest.The pepper weevil, Anthonomus eugenii, Cano (Coleoptera: Curculionidae), is one of the most destructive pests of chili pepper. It causes extensive damage on varieties selected for consumption. However, the occurrence of this pest on wild and ornamental peppers remains unknown. We investigated the consequences of chili domestication on the feeding and oviposition of A. eugenii on fruits and flowers. We used plants of one wild accession, Bird Eye Pepper, five ornamental varieties (Pops Yellow, Black Pearl, Sedona Sun, Chilli Chilli, and Salsa Deep), and two domesticated varieties selected for consumption (Scotch Bonnet and Jalapeño). First, we characterized the plants according to their fruit and flower sizes, pericarp thickness, capsaicin level, fruit position, and flower color. Then, we evaluated the susceptibility of fruits and flowers to A. eugenii. Overall, domestication increased fruit and flower sizes and pericarp thickness, altered capsaicin levels, and altered fruit position and flower color. Weevils laid more eggs and caused more feeding damage on varieties selected for consumption than on wild and ornamental plants. Our results add to the growing literature on the consequences of crop domestication on herbivores. This knowledge could be integrated into breeding programs to select varieties resistant against the pepper weevil.

CARACTERIZACIÓN MORFOLÓGICA in situ DE CHILES (Capsicum spp.) SILVESTRES Y CULTIVADOS EN LA REGIÓN USUMACINTA, TABASCO

El objetivo del trabajo fue determinar la diversidad morfológica de los chiles ('Capsicum' spp.) silvestres y cultivados en la Región Usumacinta del estado de Tabasco. En los recorridos se obtuvieron 48 colectas de chiles distribuidas en 13 morfotipos, encontradas en 12 localidades de seis municipios de la región. A cada uno se le realizó la caracterización morfológica in situ utilizando 26 variables de planta, flor y fruto con base en la guía de descriptores para Capsicum del IPGRI. Los datos se analizaron por medio de un Análisis de Componentes Principales. En los dos primeros componentes principales se reportó el 42.55 % de la variación total entre colectas. Esto explica en mayor proporción la variabilidad de fruto y planta. Por lo tanto, se puede afirmar que existe variabilidad morfológica en colectas de chiles cultivados y silvestres. Se encontró en mayor frecuencia el morfotipo cultivado tabaquero y silvestres el pico de paloma.

Transcriptome Analyses Throughout Chili Pepper Fruit Development Reveal Novel Insights into the Domestication Process.

Chili pepper (Capsicum spp.) is an important crop, as well as a model for fruit development studies and domestication. Here, we performed a time-course experiment to estimate standardized gene expression profiles with respect to fruit development for six domesticated and four wild chili pepper ancestors. We sampled the transcriptomes every 10 days from flowering to fruit maturity, and found that the mean standardized expression profiles for domesticated and wild accessions significantly differed. The mean standardized expression was higher and peaked earlier for domesticated vs. wild genotypes, particularly for genes involved in the cell cycle that ultimately control fruit size. We postulate that these gene expression changes are driven by selection pressures during domestication and show a robust network of cell cycle genes with a time shift in expression, which explains some of the differences between domesticated and wild phenotypes.

Fungal Seed Pathogens of Wild Chili Peppers Possess Multiple Mechanisms To Tolerate Capsaicinoids.

The wild chili pepper Capsicum chacoense produces the spicy defense compounds known as capsaicinoids, including capsaicin and dihydrocapsaicin, which are antagonistic to the growth of fungal pathogens. Compared to other microbes, fungi isolated from infected seeds of C. chacoense possess much higher levels of tolerance of these spicy compounds, having their growth slowed but not entirely inhibited. Previous research has shown capsaicinoids inhibit microbes by disrupting ATP production by binding NADH dehydrogenase in the electron transport chain (ETC) and, thus, throttling oxidative phosphorylation (OXPHOS). Capsaicinoids may also disrupt cell membranes. Here, we investigate capsaicinoid tolerance in fungal seed pathogens isolated from C. chacoense We selected 16 fungal isolates from four ascomycete genera (Alternaria, Colletotrichum, Fusarium, and Phomopsis). Using relative growth rate as a readout for tolerance, fungi were challenged with ETC inhibitors to infer whether fungi possess alternative respiratory enzymes and whether effects on the ETC fully explained inhibition by capsaicinoids. In all isolates, we found evidence for at least one alternative NADH dehydrogenase. In many isolates, we also found evidence for an alternative oxidase. These data suggest that wild-plant pathogens may be a rich source of alternative respiratory enzymes. We further demonstrate that these fungal isolates are capable of the breakdown of capsaicinoids. Finally, we determine that the OXPHOS theory may describe a weak primary mechanism by which dihydrocapsaicin, but not capsaicin, slows fungal growth. Our findings suggest that capsaicinoids likely disrupt membranes, in addition to energy poisoning, with implications for microbiology and human health.IMPORTANCE Plants make chemical compounds to protect themselves. For example, chili peppers produce the spicy compound capsaicin to inhibit pathogen damage and animal feeding. In humans, capsaicin binds to a membrane channel protein, creating the sensation of heat, while in microbes, capsaicin limits energy production by binding respiratory enzymes. However, some data suggest that capsaicin also disrupts membranes. Here, we studied fungal pathogens (Alternaria, Colletotrichum, Fusarium, and Phomopsis) isolated from a wild chili pepper, Capsicum chacoense By measuring growth rates in the presence of antibiotics with known respiratory targets, we inferred that wild-plant pathogens might be rich in alternative respiratory enzymes. A zone of clearance around the colonies, as well as liquid chromatography-mass spectrometry data, further indicated that these fungi can break down capsaicin. Finally, the total inhibitory effect of capsaicin was not fully explained by its effect on respiratory enzymes. Our findings lend credence to studies proposing that capsaicin may disrupt cell membranes, with implications for microbiology, as well as human health.

Ethnological Pest Management Practices of Indigenous People (Aeta/ Negrito/Ita) in Catanuan, Quezon

In the Philippines, there are more than 110 culturally diverse ethnic tribes and communities. As clearly stated in the 1987 Philippine Constitution, Article XIV, Section 17, the state shall recognize, respect, and protect the rights of the indigenous cultural communities to preserve and develop their cultures, traditions, and institutions. The Aeta, Agta or Ayta are indigenous people who live in scattered, isolated mountainous parts of Barangay San Jose (Anyao), Catanauan, Quezon. The researcher conducted an ethnological study to document the Indigenous People integrated pest management practices employing the descriptive survey method. Based on the result, 80% were still practicing the traditional way of managing the pest without harming the human and environment. The Aeta farmers leave the infected crops, manually pick burn or use smoke to eliminate the pest.Moreover, the farmers also practice crop rotation, mixed cropping, and properly manage the farm. Crop loss due to pests was one of the major problems resulting from reducing production and income. The chemical control of pests was predominant, but the Aeta farmers still practiced traditional pest control. The conventional pest control practices played a significant role in the management of agricultural land, and it was an inevitable practice for sustainable agriculture. The proper control of pests minimized economic losses and damage to the environment. Some of the respondents have insufficient skills and knowledge on the ethnological way of controlling pest and diseases using insect repellant like marigold or Amarillo, lemongrass or tanlad, oregano, and by spraying wild chili mixed with water. Based on the result, it was recommended to conduct seminars and workshops on Organic Agriculture as well as an awareness campaign on the effect of chemical fertilizer to human and environment

Free Radical-Scavenging Capacities, Phenolics and Capsaicinoids in Wild Piquin Chili (Capsicum annuum var. Glabriusculum).

The total phenolic compounds content, free radical-scavenging capacity and capsaicinoid content in populations of wild Piquin chili (C. annuum) were studied. Aqueous and hydroalcoholic extracts from nine ecotypes were evaluated. High contents of phenolic compounds and free radical-scavenging capacities were observed for both extracts; however, the values that were found for the hydroalcoholic phase were substantially higher. LC-MS analysis allowed for the detection of 32 compounds, where apigenin-8-C-glucoside followed by vanillic acid 1-O-β-o-glucopyranosylester (Isomer I or II) and 7-ethoxy-4-methylcoumarin were the most widely distributed; they were found in more than 89% of the ecotypes. The diversity of identified phenolic compounds was different among ecotypes, allowing them to be distinguished by chemical diversity, free radical-scavenging capacities and heat Scoville units. The total capsaicinoid content was higher in Population I (23.5 mg/g DW) than in Populations II and III, which had contents of 15.3 and 10.7 mg/g DW, respectively. This variability could lead to phytochemical exploitation and the conservation of the natural populations of wild chili.

Simulated Gastrointestinal Digestion, Bioaccessibility and Antioxidant Capacity of Polyphenols from Red Chiltepin (Capsicum annuum L. Var. glabriusculum) Grown in Northwest Mexico.

Chiltepin, a wild chili mostly used in different traditional foods and traditional medicine in Northwest Mexico, represents a source of polyphenols. However, studies about the bioaccessibility of polyphenols as a parameter to measure the nutritional quality and bioefficacy of them in the fruit after consumption are scarce. Chiltepin showed phenolic acids and flavonoids contents between 387 and 65μg/g, respectively. Nevertheless, these values decreased after the digestion process. Before digestion, gallic acid, 4-hydroxibenzoinc acid, chlorogenic acid, caffeic acid, p-coumaric acid, quercetin and luteolin were the main polyphenols found in chiltepin by HPLC-DAD and confirmed by FIA-ESI-IT-MS/MS. Gallic and chlorogenic acids were non-detected in the gastric phase, while only p-coumaric acid (5.35 ± 3.89μg/g), quercetin (5.91 ± 0.92μg/g) and luteolin (2.86 ± 0.62μg/g) were found in the intestinal phase. The bioaccessibility of phenolic acids, flavonoids, and total polyphenols after the intestinal phase was around 24, 17 and 23%, respectively. Overall, results indicated that release of polyphenols from chiltepin fruit might be affected by the food matrix and gastrointestinal conditions due to the low bioaccessibility values observed.

Seed dispersal as an ecosystem service: frugivore loss leads to decline of a socially valued plant, Capsicum frutescens.

Species interactions, both mutualistic and antagonistic, are widely recognized as providing important ecosystem services. Fruit‐eating animals influence plant recruitment by increasing germination during gut passage and moving seeds away from conspecifics. However, relative to studies focused on the importance of frugivores for plant population maintenance, few studies target frugivores as ecosystem service providers, and frugivores are underappreciated as ecosystem service providers relative to other mutualists such as pollinators. Here, we use an accidental experiment to elucidate the role of seed dispersal by frugivores for maintaining a culturally and economically important plant, the donne’ sali chili (Capsicum frutescens) in the Mariana Islands. One of the islands (Guam) has lost nearly all of its native forest birds due to an invasive snake (Boiga irregularis), whereas nearby islands have relatively intact bird populations. We hypothesized that frugivore loss would influence chili recruitment and abundance, which could have economic and cultural impacts. By using video cameras, we confirmed that birds were the primary seed dispersers. We used captive bird feeding trials to obtain gut‐passed seeds to use in a seedling emergence experiment. The experiment showed that gut‐passed seeds emerged sooner and at a higher proportion than seeds from whole fruits. Consistent with our findings that birds benefit chilies, we observed lower chili abundance on Guam than on islands with birds. In a survey questionnaire of island residents, the majority of residents reported an association between the wild chili and local cultural values and traditions. In addition, we identified a thriving market for chili products, suggesting benefits of wild chilies to people in the Marianas both as consumers and producers. Our study therefore documents seed dispersal as both a cultural and a supporting ecosystem service. We provide a comprehensive case study on how seed‐dispersed plants decline in the absence of their disperser, and how to apply mixed‐methods in ecosystem service assessments. Furthermore, we suggest that scientists and resource managers may utilize fruit–frugivore mutualisms concerning socially valuable plants to gather support for frugivore and forest conservation efforts.

Morphological diversity of wild and semi-wild chili populations of Tabasco and the north of Chiapas States, Mexico

Morphological diversity of wild and semi-wild chili populations of Tabasco and the north of Chiapas States, Mexico

Effects of temperature on wild chili pepper (Capsicum annuum var. glabriusculum) germination grown under two light conditions

The populations of wild chili pepper (Capsicum annuum var. glabriusculum) are a genetic valuable resource and the knowledge of the germinative ability, is of great importance for its management and conservation. The effects of the temperature on germination of wild chili grown in two environment of light, and the relation with the weight of 100 seeds of five populations of wild chili of the Northwest of Mexico, were recorded. The mother plants grown in greenhouse conditions with 50 and 100 % of solar light. The treatments applied in the germination cameras matched: Fluctuating temperature (25-35 ºC) and constant temperature (25 ºC). The treatment variables were the following: percentage of final germination and mean germination time (T50). These variables performed a greatest treatment response of fluctuating temperature. A widely variation among 50 and 100 % of light was recorded with natural conditions. These temperature fluctuations are determinant in germinative processes. The temperature performed a significantly response in terms of the effect in germination velocity (T50) but not in germination percentage. The final germination was not significantly correlated with the seed weight due to maternal effects. In addition, plants grown in greenhouse conditions, differentiate among populations with a genetic basis.

Gut passage and secondary metabolites alter the source of post-dispersal predation for bird-dispersed chili seeds.

Plants can influence the source and severity of seed predation through various mechanisms; the use of secondary metabolites for chemical defense, for example, is well documented. Gut passage by frugivores can also reduce mortality of animal-dispersed seeds, although this mechanism has gained far less attention than secondary metabolites. Apart from influencing the severity of seed predation, gut passage may also influence the source of seed predation. In Bolivia, we compared impacts of these two mechanisms, gut passage and secondary metabolites, on the source of seed predation in Capsicum chacoense, a wild chili species that is polymorphic for pungency (individual plants either produce fruits and seeds containing or lacking capsaicinoids). Using physical exclosures, we isolated seed removal by insects, mammals, and birds; seeds in the trials were from either pungent or non-pungent fruits and were either passed or not passed by seed-dispersing birds. Pungency had little influence on total short-term seed removal by animals, although prior work on this species indicates that capsaicin reduces mortality caused by fungi at longer time scales. Gut passage strongly reduced removal by insects, altering the relative impact of the three predator types. The weak impact of pungency on short-term predation contrasts with previous studies, highlighting the context dependence of secondary metabolites. The strong impact of gut passage demonstrates that this mechanism alone can influence which seed predators consume seeds, and that impacts of gut passage can be larger than those of secondary metabolites, which are more commonly acknowledged as a defense mechanism.

Does Gut Passage Affect Post-dispersal Seed Fate in a Wild Chili, Capsicum annuum?

Abstract Seeds of Capsicum spp. (wild chilies ) are coated with capsaicin, which deters mammalian seed predators. During gut passage through frugivorous birds, its presence on seeds likely is greatly reduced, presumably increasing the seeds' susceptibility to postdispersal seed predation by mammals. We tested whether gut passage influences the rate at which dispersed seeds are removed from dispersal sites by different types of seed consumers. We predicted that seeds passed through birds (passed seeds) would be removed at higher rates than seeds taken directly from fruits (non-passed seeds). Removal rates of passed seeds were either lower or no different than removal rates of non-passed seeds, contrary to our prediction. In a second set of trials, we placed caged and exposed (control) seeds in pairs on the ground to determine whether vertebrates or invertebrates were primarily responsible for post-dispersal seed removal. We found an inconsistent effect of caging on frequency of seed removal, indicating tha...

Heterochromatin type, amount and distribution in wild species of chili peppers (Capsicum, Solanaceae)

Triple staining with the fluorochromes chromomycin A3, distamycin A and 4′-6-diamidino-2-phenylindole (CMA/DA/DAPI) was applied to somatic metaphases and interphase nuclei of 11 taxa of wild chili peppers (Capsicum), with 2n = 2x = 24 (C. annuum var. glabriusculum, C. cardenasii, C. chacoense, C. flexuosum, C. galapagoense, C. eximium, C. praetermissum and C. tovarii) and 2n = 2x = 26 (C. recurvatum, C. rhomboideum and C. villosum) to analyse heterochromatin type, amount and distribution in wild members of this genus. Heterochromatic banding patterns allowed the identification of all the taxa examined and contributed to their taxonomic grouping. GC-rich heterochromatin (CMA+/DAPI−) was typical in all taxa; only C. praetermissum possessed also AT-rich (CMA−/DAPI+) and mixed GC- and AT-rich (CMA+/DAPI+) bands. Heterochromatin amount (expressed as % of karyotype length) ranged between 1.72 (C. chacoense) and 16.82 (C. flexuosum) and was positively correlated with karyotype length in most of the taxa examined. Heterochromatin located mainly at terminal position of chromosomes but intercalary position prevailed in C. flexuosum. Nucleolus organizer regions (NOR)-associated GC-rich heterochromatin was exclusively terminal and included the distal macrosatellite and a small portion on the corresponding arm. In all the taxa analysed, an equilocal heterochromatin distribution in non-homologous chromosomes of karyotype was observed, suggesting concerted evolution of heterochromatin dispersion in Capsicum.

Why are not all chilies hot? A trade-off limits pungency

Evolutionary biologists increasingly recognize that evolution can be constrained by trade-offs, yet our understanding of how and when such constraints are manifested and whether they restrict adaptive divergence in populations remains limited. Here, we show that spatial heterogeneity in moisture maintains a polymorphism for pungency (heat) among natural populations of wild chilies (Capsicum chacoense) because traits influencing water-use efficiency are functionally integrated with traits controlling pungency (the production of capsaicinoids). Pungent and non-pungent chilies occur along a cline in moisture that spans their native range in Bolivia, and the proportion of pungent plants in populations increases with greater moisture availability. In high moisture environments, pungency is beneficial because capsaicinoids protect the fruit from pathogenic fungi, and is not costly because pungent and non-pungent chilies grown in well-watered conditions produce equal numbers of seeds. In low moisture environments, pungency is less beneficial as the risk of fungal infection is lower, and carries a significant cost because, under drought stress, seed production in pungent chilies is reduced by 50 per cent relative to non-pungent plants grown in identical conditions. This large difference in seed production under water-stressed (WS) conditions explains the existence of populations dominated by non-pungent plants, and appears to result from a genetic correlation between pungency and stomatal density: non-pungent plants, segregating from intra-population crosses, exhibit significantly lower stomatal density (p = 0.003), thereby reducing gas exchange under WS conditions. These results demonstrate the importance of trait integration in constraining adaptive divergence among populations.

Evolutionary ecology of pungency in wild chilies

The primary function of fruit is to attract animals that disperse viable seeds, but the nutritional rewards that attract beneficial consumers also attract consumers that kill seeds instead of dispersing them. Many of these unwanted consumers are microbes, and microbial defense is commonly invoked to explain the bitter, distasteful, occasionally toxic chemicals found in many ripe fruits. This explanation has been criticized, however, due to a lack of evidence that microbial consumers influence fruit chemistry in wild populations. In the present study, we use wild chilies to show that chemical defense of ripe fruit reflects variation in the risk of microbial attack. Capsaicinoids are the chemicals responsible for the well known pungency of chili fruits. Capsicum chacoense is naturally polymorphic for the production of capsaicinoids and displays geographic variation in the proportion of individual plants in a population that produce capsaicinoids. We show that this variation is directly linked to variation in the damage caused by a fungal pathogen of chili seeds. We find that Fusarium fungus is the primary cause of predispersal chili seed mortality, and we experimentally demonstrate that capsaicinoids protect chili seeds from Fusarium. Further, foraging by hemipteran insects facilitates the entry of Fusarium into fruits, and we show that variation in hemipteran foraging pressure among chili populations predicts the proportion of plants in a population producing capsaicinoids. These results suggest that the pungency in chilies may be an adaptive response to selection by a microbial pathogen, supporting the influence of microbial consumers on fruit chemistry.

COSTS AND BENEFITS OF CAPSAICIN-MEDIATED CONTROL OF GUT RETENTION IN DISPERSERS OF WILD CHILIES

A fundamental way in which animal-dispersed plants can influence the viability and distribution of dispersed seeds is through control of retention time in the guts of dispersers. Using two species of wild chilies and their dispersers, we examined how chemical and physical properties of fruits and seeds mediate this interaction. Capsicum chacoense is polymorphic for pungency, occurs in Bolivia, and is dispersed mostly by elaenias. Capsicum annuum is not polymorphic, occurs in Arizona (USA), and is dispersed mostly by thrashers. We first tested whether capsaicin, the substance responsible for the pungency of chilies, affects gut retention time of seeds in primary dispersers. Capsaicin slowed gut passage of seeds but did so in a manner that differed greatly between bird species because the constipative effects of capsaicin occurred only after an 80-minute time lag. Elaenias in Bolivia held only 6% of C. chacoense seeds for > 80 minutes, whereas thrashers in Arizona held 78% of C. annuum seeds for > 80 minutes. Next we examined the effects of retention time on seed viability and germination. Increased retention resulted in a greater proportion of seeds germinating in C. annuum, had no effects on non-pungent C. chacoense, and had negative effects on pungent C. chacoense. These divergent effects are explained by differences in seed coat morphology: seed coats of pungent C. chacoense are 10-12% thinner than those of the other two types of seeds. Thus, longer retention times damaged seeds with the thinnest seed coats. In C. annuum, seed viability remained high regardless of retention time, but germination increased with retention, suggesting a role for scarification. Thus, in C. annuum, fruit chemistry appears well matched with seed morphology and disperser physiology: capsaicin extends gut retention for most seeds, resulting in greater seed scarification and higher germination rates. Increased retention of pungent C. chacoense seeds is detrimental, but because the primary consumers have short retention times, capsaicin slows only a small proportion of seeds, minimizing negative effects. These results illustrate the importance of context in studies of fruit secondary metabolites. The same chemical can have different impacts on plant fitness depending on its morphological, physiological, and ecological context.

A field test of the directed deterrence hypothesis in two species of wild chili

The directed deterrence hypothesis posits that secondary metabolites in ripe fruit function to deter fruit consumption by vertebrates that do not disperse seeds, while not impacting consumption by those that do. We tested this hypothesis in two species of wild chilies (Capsicum spp.). Both produce fruits that contain capsaicinoids, the compounds responsible for the pungency of chilies. Previous work suggests seed-dispersing birds but not seed-destroying rodents consume chili fruits, presumably because rodents are deterred by capsaicin. However, fruit removal from chili plants by rodents and other mammals has not been previously explored. Because laboratory rodents can develop a preference for capsaicin, it is quite possible that wild rodents are natural consumers of chili fruits. We monitored the fate of 125 marked fruits of Capsicum chacoense and 291 fruits of Capsicum annuum. For both species, essentially all fruit removal occurred during the day, when rodents are inactive. Video monitoring revealed fruit removal only by birds, mostly by species known to disperse chili seeds in viable condition. Furthermore, these species are from taxonomic groups that tend to specialize on lipid-rich fruits. Both species of chili produce fruits that are unusually high in lipids (35% in C. chacoense, 24% in C. annuum). These results support the directed deterrence hypothesis and suggest that fruiting plants distinguish between seed predators and seed dispersers by producing fruits that repel the former and attract the latter.