Jaborandi is the common name for Pilocarpus species, which comes from the Tupi-Guarani language ya-mbor-endi, meaning “what causes slobbering”. Traditional knowledge related to jaborandi plants is assumed to be one of the most precious inheritances of Amazonian indigenous culture, where this plant is historically used for medicinal purposes. Users have observed that infusions of jaborandi leaves have the property of stimulating the production of sweat and salivation, and they are applied in shamanic rituals for fever treatment, stomatitis and as an antidote for poisons and toxins (Holmstedt et al., 1979). This knowledge spread through the generations and cultures, resulting in the wide use of this plant in popular medicine by native people and the people who came from abroad after the XVI century (see the short description of Pilocarpus records in Fig. 1).

Fig. 1.

Brief chronological records related to the Pilocarpus genus. (1) Jaborandi mentioned as a medicinal plant in the Soares de Souza (Portuguese) annotations. These manuscripts were written during the 17 years he lived in the Brazilian territory (1570–1587). (2) Plant traits and usages by locals described by the naturalist George Marcgrave (German) in the first official publication dedicated to the Brazilian native plants. (3) Pilocarpus defined as a genus by the description of Pilocarpus racemosus plants. (4) The physician Symphronio Coutinho (Brazilian) took samples of jaborandi leaves to be studied in Europe. By this time, jaborandi leaf extracts were used as diaphoretics and sialagogues. (5) Pilocarpine isolation as crystalline salts from the leaves of two Pilocarpus species in independent works performed in France (Hardy, 1875) and England (Gerrard, 1875). (6) Pilocarpine used by Adolf Weber (German ophthalmologist) to reduce intraocular pressure and eventually in glaucoma therapies. (7) Development of economically viable methods to extract pilocarpine from jaborandi leaves (Louis Merck thesis). As a consequence, the Merck Company began pilocarpine salt extraction in Germany from imported leaves (Brazil). (8) Marc Jacobs S.A. exports dried Pilocarpus leaves from Brazil. This company, built by French immigrants on the Brazilian northeast coast (Piauí State), exported 200kg packages of dried Pilocarpus leaves collected in natural conditions (forest). (9) The Merck Company establishes operations in Brazilian territory prospecting for plant substances with medicinal properties. (10) The Brazilian company PVP begins pilocarpine nitrate extraction. (11) Period of maximal leaf harvesting in natural conditions. Combined with habitat loss due to Amazon deforestation, this period was marked by significant Pilocarpus population declines. (12) Merck starts a Pilocarpus domestication program by establishing a field area with approximately 3million plants. Accessions selected from several natural populations were planted over 300ha. (13) Pilocarpus microphyllus and three other Pilocarpus species are included on the Brazilian list of endangered plant species because of reductions in expressive natural genetic diversity. (14) Beginning of conservation programs and sustainable management of Pilocarpus microphyllus in protected areas.

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The stimulation effects observed derivate from the imidazole alkaloid pilocarpine. The active ingredient extracted from jaborandi leaves acts as a cholinergic parasympathomimetic agent, i.e., it stimulates secretions in sweat, lachrymal and salivary glands (Fox et al., 2016; Sidhu, 2014). Since its isolation (Gerrard, 1875; Hardy, 1875) and the discovery of its power to reduce intraocular pressure (Sneader, 2005), pilocarpine has constituted the base of several medicaments, especially those applied in glaucoma treatment. More recently, it has also been used to reduce xerostomia induced by head and neck radiation therapy and for the treatment of Sjogren's syndrome (dry mouth) (Gornitsky et al., 2004; Sidhu, 2014).

The genus Pilocarpus (Rutaceae) is the only natural and economically viable source of pilocarpine currently known (Abreu et al., 2007). Despite the occurrence of pilocarpine in several Pilocarpus species, it is essentially obtained from Pilocarpus microphyllus Stapf ex Wardleworth because of the high pilocarpine concentration in the leaves of this species (Pinheiro, 2002) and due to its supposedly broad geographic distribution (Kaastra, 1982). The habitat loss resulting from Amazon deforestation and the uncontrolled extractivism of jaborandi leaves (especially in the 1970s and 1980s) led to a depletion of the plant population, with an estimated reduction of natural populations by approximately 50% (Martinelli and Moraes, 2013). Therefore, since 1992, P. microphyllus has been included on the List of Endangered Brazilian Plant Species (IBAMA n° 37, 1992), along with two other Pilocarpus species (P. jaborandi Holmes and P. trachylophus Holmes). More recently, another Pilocarpus species (P. alatus C. J. Joseph ex Skorupa) was also added to the Brazilian red list, since its populations have also undergone a significant reduction (Martinelli and Moraes, 2013). In addition, jaborandi leaf harvesting under natural conditions constitutes an important income source for communities living in poor regions of Brazil. Here, we compile our understanding of the genus Pilocarpus, including knowledge gaps related to its natural occurrence, genetic variability, pilocarpine concentrations, pilocarpine synthesis pathway and domestication/cultivation, as well as socioeconomic aspects of the species P. microphyllus.

The genus Pilocarpus was firstly described by Martin Vahl in 1797 (Vahl, 1797) from the species Pilocarpus racemosus Vahl. Despite its importance as a widely used medicinal plant, most complete taxonomic studies of this genus were only latterly performed by Kaastra (1982) and Skorupa (1996), who identified 16 Pilocarpus species. Currently, we found 17 described and recognized species in the repository The Plant List (www.theplantlist.org) and 43 scientific plant names proposed for the Pilocarpus genus, involving synonymies and potentially new species (Supplemental Table 1). These species present a widespread distribution in Latin America, occurring from southern Central America (Mexico) to southern South America. The north and northwest portions of South America contain a large part of these species, especially in the Brazilian territory, which harbors 13 species, with 11 being endemic to Brazil (Skorupa, 2000). As a consequence, this part of the continent is recognized as the center of genetic diversity of Pilocarpus species (Oliveira, 2007).

Pilocarpus microphyllus is a tree reaching 1–6m in height, with a terminal raceme 15–40cm in length as the most common inflorescence type (Fig. 2). Leaves are composite and glabrous, and the leaflets vary in shape and color, are commonly elliptical, exhibit opposite lateral insertion, are 1.5–6×1–3.5cm and sessile and have an emarginated apex (Skorupa, 2000). We can observe substantial morphological variation in the leaf traits of different accessions growing under the same environmental conditions (Fig. 3), suggesting potentially large genetic variability in this species, at least for some traits (Moura et al., 2005b).

Fig. 2.

Growth and reproduction stages of Pilocarpus microphyllus plants. (a) Mature plant reaching approximately 2.5m height; (b) seedling growing in the forest understory; (c) flowers; (d) immature and mature fruits and; (e) seeds collected after fruit dehiscence.

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Fig. 3.

Morphological variations in Pilocarpus microphyllus leaves. Leaf samples were collected from plants growing under the same environmental conditions, in a germplasm bank at Embrapa (Brazilian Agricultural Research Corporation) Belem, PA, Brazil.

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Described to naturally occur mainly in the northern region of Brazil (comprising the states of Pará, Maranhão and Piauí) and some locations in Suriname (Santos and Moreno, 2004; Skorupa, 1996), the potential distribution of P. microphyllus may be larger than currently observed. For the present study, we designed a potential distribution model considering the public data available from speciesLink (http://www.splink.org.br/) and the Global Biodiversity Information Facility (GBIF, http://www.gbif.org/). In the construction of this model, we used the eight least correlated bioclimatic layers with 30 arc-seconds obtained from the Worldclim variables (Hijmans et al., 2005) and the Maxent algorithm (Phillips et al., 2006). The ROC-AUC (area under receiver-operating curve), whose values near 1.0 indicate good results (Fielding and Bell, 1997), was calculated. Additionally, to describe the main environmental features where P. microphyllus was recorded, we used the same dataset of occurrence points to calculate the frequency distribution considering three topo-climatic variables: altitude, annual mean temperature and annual precipitation using ArcGIS (Esri Inc.). As expected, the model shows that Piauí, Maranhão, and Pará contain the most representative jaborandi areas (Fig. 4). It also shows that northern areas of Ceará and Tocantins are suitable for the occurrence of this species. Additionally, the model suggests that some areas in the south of French Guiana, Suriname and Guyana as well as the Brazilian states of Amazonas, Roraima and Amapá are also suitable for the occurrence of P. microphyllus. For some of these locations (Guyana, Amazonas, Roraima, Amapá, Tocantins and Ceará), there is no record of P. microphyllus so far, and these areas should be checked through field studies. Particularly in the Brazilian territory, these areas have little biodiversity data available.

Fig. 4.

Potential distribution of Pilocarpus microphyllus. Warm colors (close to red) indicate a high probability of occurrence and the most suitable areas for the species. Black points indicate sites where P. microphyllus plants were collected. Box on the right highlights the National Reserves of Carajás and Tapirapé-Aquiri.

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Results from the model suggest that P. microphyllus has a great probability of occurrence in regions with low altitudes (0–100m), annual precipitation of approximately 1300–1700mm, and a mean annual temperature between 25.5 and 27°C (Supplemental Fig. 1). These results confirm previous studies (Santos and Moreno, 2004; Skorupa, 1996) suggesting that P. microphyllus is mainly found in the lowlands of Amazon Tropical Moist Forest, despite reported occurrences of this species in environmental conditions such as those in the Caatinga Dry Forest in the Northeast region of Brazil. Overall, our results suggest that P. microphyllus can be found growing outside the limits of the three Brazilian states (Maranhão, Pará and Piauí), supporting the hypothesis that P. microphyllus is not a Brazilian endemic species (Martinelli and Moraes, 2013). In addition, the occurrence of this species in the northwestern portion of the species potential distribution map needs confirmation through field surveys.

The two National Reserves highlighted in Fig. 4, Carajás and Tapirapé-Aquiri, likely contain the largest remaining P. microphyllus populations and may act as natural reserves of genetic diversity for this species. Both of these areas have undergone intensive deforestation pressure inside and outside their limits, causing a consequent threat to several species, such as P. microphyllus. Outside the reserves, cattle farms have expanded into large areas that currently reach the reserve borders (Souza-Filho et al., 2016). Inside, mining is also expanding into the areas where P. microphyllus frequently occurs, i.e., the borders of iron crust inselbergs in the Amazon Forest, called Canga ecosystems (Canga is a Brazilian common name used to designate the ecosystems associated with the superficial ironstone (Skirycz et al., 2014)). Because local people predominantly collect leaves of P. microphyllus in these areas, especially in the Carajás National Reserve, management programs and reforestation with this species are highly recommended.

Karyotype analyses have provided several tools for plant breeding programs that can be applied in different phases of the process to develop new cultivars from accessions of a germplasm bank (Singh, 2003; Sybenga, 1992). However, as generally observed for most of the angiosperm families with recognized economic importance (Guerra, 2008), only a few groups in the Rutaceae have cytogenetic data available, as is the case of Citrus and related genera (see, for instance, Carvalho et al., 2005; Mendes et al., 2011; Silva et al., 2015). For Pilocarpus species, however, the chromosome numbers of only eight species (out of the 17 spp. in the genus) are available in the literature (P. giganteus, P. grandiflorus, P. microphyllus, P. pauciflorus, P. sulcatus and P. trachylophus, with 2n=44, and the two putative tetraploids P. carajaensis and P. spicatus, with 2n=88) (Skorupa, 2000). There is a lack of information on the divergence/similarity levels among karyotypes, which may be important in better directing interspecific hybridizations in jaborandi breeding programs (see Chen et al., 2003).

In addition, there are few studies addressing the genetic diversity of jaborandi (see Moura et al., 2005a,b; Sandhu et al., 2006; Rocha et al., 2014), which is a noteworthy fact, considering the importance of the species. However, two out of the four published analyses (Rocha et al., 2014; Sandhu et al., 2006) sampled a very limited number of genotypes because their primary interest was to find molecular markers rather than conduct a more detailed characterization of natural populations or compile germplasm banks. Sandhu et al. (2006) attempted to describe RAPD (Random Amplified Polymorphic DNA) markers associated with contrasting levels of pilocarpine accumulation in the leaves of 20 individuals collected from a natural population in the Brazilian state of Maranhão, but they did not succeed in finding such relationships. More recently, Rocha et al. (2014) tested the applicability of 48 ISSR (Inter-Simple Sequence Repeat) primers for genetic diversity analyses among jaborandi populations and reported some promising markers with high levels of polymorphism indexes.

On the other hand, a considerably larger sample was used in a study with two aims, one to evaluate the discriminatory power of RAPD markers (Moura et al., 2005a) and the other to use morphological leaf traits to access the genetic diversity among different populations of jaborandi (Moura et al., 2005b). Although moderate genetic variability among the tested accessions was observed in both studies, the authors could not observe geographic structure among the collection plots in addition to observing higher molecular variance within (75.84%) than among populations (26.16%) in the RAPD assay (Moura et al., 2005a). Despite the studies recognizing the existence of enough diversity in natural populations for genetic breeding programs, there is not enough knowledge on the genetic diversity of the species to assure successful programs.

Considering the current conservation status of wild jaborandi populations, the development and application of molecular biology tools to find genetic markers is mandatory. In contrast to the dominant nature of both RAPD and ISSR markers, i.e., there is not information on both alleles of a given locus, co-dominant marker systems (which assess both alleles) offer a better view of the genotypes by providing the assessment of a wider range of populational parameters (see Weising et al., 2005; Nybom et al., 2014). Favored by recent advances in sequencing technologies, the development of either single- or multi-locus co-dominant markers, such as the traditional and widely used SSR (or Simple Sequence Repeats, or microsatellites) and SNP (Single Nucleotide Polymorphisms) marker systems, respectively, has been significantly faster and more cost-effective over the last decade (Metzker, 2010; Nybom et al., 2014). Therefore, future investments in jaborandi breeding programs should be focused on developing such co-dominant markers for the species by planning large-scale genotyping of both natural populations and cultivated accessions in order to direct the first steps of the more efficient genetic improvement of cultivars with traits of interest, such as higher pilocarpine concentrations.

Most of the plant phenology studies conducted in the tropics have been carried out at the community level, addressing specific life events, such as flowering and fructification (Croat, 1969; Frankie et al., 1974; Haugaasen and Peres, 2005; Morellato and leitao-Filho, 1996; Muniz, 2008). This was the case for P. microphyllus until recently, when (Muniz, (2008) determined the timing of flowering (April to May) and fructification (May to August) for this species in Northeast Brazil. These phenophases, shared with the other species also growing in the same forest understory, occur at the end of the wet season, contrasting with other species occupying the forest canopy (Croat, 1969; Muniz, 2008).

We recently performed a more comprehensive phenological study of P. microphyllus by monitoring vegetative (leaf fall and leafing) and reproductive (flower bud, flowering, fructification) events of 414 plants growing in the Carajás Natural Reserve (North Brazil) over 27 months (February 2014 to May 2016). In this study, the activity and intensity of each event were monitored monthly, following the methods proposed by (Bencke and Morellato, (2002) and (Fournier, (1974). We observed leaf fall in a large part of the plants over almost the entire period of evaluation (Fig. 5a). However, because the intensity of this event remained constantly at low values, P. microphyllus can be classified as an evergreen species (Rivera et al., 2002) in the studied site. Canopy renovation by leafing occurred continuously, with a peak of activity and intensity of this phenophase between September and January (Fig. 5b), a period coinciding with the transition of the dry to wet season in the Carajás National Reserve (Supplemental Fig. 2), aligning the leaf-growing period with the wet season. Because leaves are predominantly harvested in the forest during the dry season (June–September), most of these leaves have completed their growth, and the period of leafing can be avoided, which is essential in plant canopy recovery and leaf productivity.

Fig. 5.

Monthly time series of leaf phenology and reproductive events of Pilocarpus microphyllus plants growing under natural conditions (undisturbed areas) in the Carajás National Forest, Pará/Brazil. (a) Leaf fall, (b) Leafing, (c) Flower bud, (d) Flower anthesis and (e) Fructification. Data were recorded from 414 plants over 27 months. Solid and dotted lines represents the activity and the intensity of each phenophase, respectively.

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The flowering (flower budding and flower anthesis) of P. microphyllus plants occurred during several months of the year, suggesting a possible annual pattern of long duration (Newstrom et al., 1994). Flower buds initially appeared in December, having maximal activity and intensity between February and April (Fig. 5c). We observed flower anthesis almost simultaneously (one month later) following a similar trend as described for the flower buds (Fig. 5d). The overall lower activity and intensity of this phenophase suggests possible leaf bud abortion, reducing the number of developed flowers or the duration over which the flowers remain open. Fructification also showed a regular annual pattern, starting in February, with a peak between May and June, and ending by July/August (Fig. 5e), when the dry period occurs in the region, which may favor seed dispersal because P. microphyllus has dry fruits with explosive dehiscence.

The earlier occurrence of reproductive events (flowering and fructification) we observed at the studied site compared to those described by Muniz (2008) is consistent with the suggestion that water availability drives most of the phenological patterns in the tropics (Fenner, 1998). While at both sites (500km distant from each other), flowering occurred in the middle of the wet season followed by fructification, which ends when precipitation declines, precipitation at the site where we performed our study started earlier (September–October) when compared to the Muniz site (November) (Supplemental Fig. 2). We could expect phenological patterns that are not synchronized with the changing of the seasons because P. microphyllus grows in the tropics. In these areas, it is common to observe continuous, sub-annual, annual, or supra-annual events (Newstrom et al., 1994; Sarmiento and Monasterio, 1983) that are normally associated with the diversity of pressures (biotic and abiotic) affecting these communities (Fenner, 1998). Nonetheless, the number of studies observing synchronism between plant events even when climatic seasonality is not obvious is increasing (Borchert et al., 2005; Caldeira et al., 2008; Menzel et al., 2006; Newstrom et al., 1994). In addition, observations of P. microphyllus phenological patterns in populations occurring in areas other than those that have been already studied will shed some light in regard to the behavior of such species.

Alkaloids constitute the most abundant secondary metabolites found in the leaves of Pilocarpus spp. (Kaastra, 1982). Their abundance may show seasonal (Abreu et al., 2007), developmental stage, and plant segment levels (Abreu et al., 2011; Andrade-Neto et al., 2002; Sawaya et al., 2011). The concentrations of the imidazole alkaloid pilocarpine can reach up to 1.04% of the leaf dry mass of P. microphyllus species (Costa, 2012). In our phenotyping study currently in progress (91 accessions of P. microphyllus), we identified accessions having pilocarpine leaf concentrations varying between 0.2 and 2.2%. This alkaloid is found in various concentrations in the leaves of six out of the seven Pilocarpus species analyzed so far (nearly zero pilocarpine was obtained from P. spicatus leaves, Sawaya et al., 2011). In this study, Sawaya et al. (2011) observed that the pilocarpine content may be higher in other Pilocarpus species (P. jaborandi and P. racemosus) than in P. microphyllus. Despite the similar total alkaloid content in these species (approximately 1% of the leaf dry mass), an overall lower pilocarpine content (less than 35% of the total alkaloids) was obtained from the two P. microphyllus accessions tested. A combination of events may have led to these results, including substantial genetic variability in this species (Sandhu et al., 2006), variation in the environmental conditions (plants cultivated similar to crops) (Sawaya et al., 2011) and plant/leaf age (Abreu et al., 2011). On the other hand, the considerable pilocarpine content found in P. jaborandi and P. racemosus enables them to be used as potential sources of pilocarpine.

Brazil is the only known country commercially supplying pilocarpine (CNI, 2014), probably because of the natural occurrence and abundance of the species P. microphyllus. As a result of market demand, the harvesting of jaborandi leaves in nature was maximized between 1950 and 1990 (Berlinck, 2012), reaching its peak around the 1970s, when the state of Maranhão (major producer) alone provided more than 2500tonyear−1 of dried leaves (Fig. 6). A significant leaf yield reduction in these areas began in the early 1990s, when it was partially buffered by increasing harvesting in new areas, such as in the Carajás mountain range in the state of Pará (Grabher, 2015). The intense harvesting in these areas without a management program compromised the sustainability of this activity especially for the major P. microphyllus populations growing inside national forests (Carajás and Tapirapé-Aquiri), where environmental agencies started controlling and organizing the extractivism. Additionally, the establishment of mining operations in these areas also affected the mobility of leaf collectors and the availability of plants, since P. microphyllus usually occurs close to the mining areas in these National Forests.

Fig. 6.

Overall reduction in Pilocarpus microphyllus leaf harvesting in natural conditions (forest). Main panel: time series of the total leaves harvested in Brazilian territory and upper panel: time series of the leaves harvested in the Brazilian states with major production (data source: 1975–1985 compiled from Pinheiro; 1986–2014 from Brazilian Institute of Geography and Statistics-IBGE).

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Motivated by the reduction in the raw material from nature and the need to supply pilocarpine demand, the Merck company, which holds a pilocarpine extraction patent and was the major pilocarpine supplier until recently, initiated a jaborandi domestication program in 1989–1990 by selecting accessions and establishing a jaborandi plantation with more than 3 million plants (300ha) in Maranhão. Currently, this farm has approximately 15 million jaborandi plants. It is owned by Centroflora Group, a Brazilian company devoted to extracting and processing compounds from jaborandi (and other species), especially those associated with the pharmaceutical and cosmetic industries. However, similar operations have not yet been established in other locations where P. microphyllus occurs.

The jaborandi market has played an important economic role by creating job opportunities and providing important income by connecting collectors to the pharmaceutical industry. It has been suggested that jaborandi extractivism corresponded to major revenue for thousands of families in the Brazilian Northeast region during the peak of extraction (1970–1980), estimated to reach up to 25 and 1.2 thousand families in Maranhão and Pará, respectively (Homma, 2003). Despite the market fluctuations and the reduction in areas where it naturally occurs, jaborandi is still being exploited, mainly in wild areas. Overall, these activities remain economically feasible because the pilocarpine price has experienced a significant increase (up to 36%) in the last two decades, when the pilocarpine supply capacity declined while its demand did not (IBGE, 2014). Moreover, pilocarpine is currently the eighth most exported pharmaceutical substance from Brazil, reaching around U$ 6.8millionyear−1 (Grabher, 2015). Increasing the number of cultivated areas and establishing natural reserves to maintain genetic diversity and population viability may sustain this activity and preserve the threatened Pilocarpus species.

Conservation programs and management plans have been established for some species in the Carajás National Reserve (Pará, Brazil). More recently, a group involving the mining company Vale S. A. and institutions such as the environmental agencies IBAMA (Brazilian Institute of Environment and Renewable Natural Resources) and ICMBio (Chico Mendes Institute for Biodiversity Conservation) began promoting a series of conservational and social activities in this National Forest and surrounding communities. In regard to P. microphyllus activities, it includes (i) the establishment of a germplasm bank and rescue accessions, involving the reintroduction of thousands plants in areas designated for conservation and sustainable uses; (ii) a series of studies aiming to map populations inside the Carajás National Reserve, determine their growth dynamics, genetic diversity, and pilocarpine content and select genotypes for cultivation purposes considering efficient propagation protocols and nutritional requirements to maximize yield (pilocarpine and biomass); and (iii) helping collectors organize a cooperative (CoEx-Carajás) and perform sustainable management of P. microphyllus and other native species to generate income.

Several approaches have been used in an attempt to improve the yield of crops and other plant species. In contrast to most common crops (maize, rice, wheat, etc.), for which environmental conditions favorable for growth and biomass production are translated into increased yield, improving the yield of medicinal plants is not necessarily linked to biomass accumulation. Most of the products extracted from these plants (secondary metabolites) often require some degree of stressful conditions to trigger and/or boost the biosynthetic process (Akula and Ravishankar, 2011; Avancini et al., 2003; Zhao et al., 2005). As an example, when P. microphyllus plant leaves were treated with methyl-jasmonate or salicylic acid, pilocarpine content increased up to 4-fold when compared to the control (null treatment) (Avancini et al., 2003). However, when the same Pilocarpus species is cultivated as a crop, with soil preparation, adequate nutrients and water supply via irrigation, the pilocarpine content of leaves can be reduced to approximately 0.5%, while we found a mean of 1.2% in the 91 accessions we have collected so far.

Techniques for cultivating P. microphyllus remain incomplete and have not yielded maximal productivity because of the few and fragmented studies conducted so far. A large part of these studies involved metabolite identification (Abreu et al., 2007; Santos and Moreno, 2004; Sawaya et al., 2011), taxonomy (Kaastra, 1982; Skorupa, 2003, 1996), and in vitro cell culture (Abreu et al., 2005; Sabá et al., 2002). Some studies provided information regarding propagation by seeds (Calil et al., 2008), micropropagation (Sabá et al., 2002) and potential relationships between low nutrients and pilocarpine (Avancini et al., 2003), but none have addressed genotype selection, nutrient requirements or culture management.

Pilocarpus is a well-known plant genus, especially because of the medicinal importance of pilocarpine. As one of the most extracted and exported pharmaceutical constituents from Brazil, pilocarpine is an important source of income for many families depending on the extractivism of P. microphyllus leaves. Because of the absence of sustainable management for this natural resource, four (out of 17) of the Pilocarpus species (P. microphyllus included) were placed on Brazilian threatened plant species lists. Almost three decades later, limited progress has been made in terms of the continuous reduction of genetic diversity and population size of these species, causing the necessity for conservation programs.

Since the demand for natural pilocarpine remains high because there is no viable synthetic process and no efficient substitute active ingredient, sustainable management in natural areas and the cultivation of P. microphyllus are potential avenues for the conservation of this species. The establishment of a germplasm bank is one alternative that can be used in an effort toward preservation and as a source of genetic material for breeding. We suggest that conservation programs should pay attention to the development of adaptive management that will allow local families to cultivate this species. Such efforts will be expected to reduce the demand for the current unsustainable P. microphyllus harvesting in natural conditions. To do so, a sequence of multidisciplinary studies will be necessary, including those focused on genotype selection, propagation, the maximization of biomass and pilocarpine production, and the identification of nutritional requirements and environmental conditions that will improve pilocarpine yield.

This work was financially supported by Vale S. A. in cooperation with the Instituto Tecnológico Vale (Grant no. 4600034107).