Fig 1.
Examples of flowers and fruits from the five cultivated species: a) C. annuum; b) C. chinense; c) C. frutescens; d) C. baccatum; and e) C. pubescens.
Capsicum annuum and her sister species, C. chinense and C. frutescens all have white flowers. The flowers of Capsicum baccatum have yellow-green spots on the white petals. Capsicum pubescens can be distinguished by purple flowers. Photo credits: Centro de Investigación y Desarrollo Rural Amazónico (CIDRA), Xavier Scheldeman, Maarten van Zonneveld.
Fig 2.
Capsicum eximium fruits, flowers and shrub in the backyard of a Bolivian farm, in Padilla, Chuquisaca.
The fruits of this species are known as ´ulupica´. This is one of the several wild peppers, which is consumed in Bolivia. Photo credits: Maarten van Zonneveld.
Fig 3.
Cultivated Capsicum gene pools.
Capsicum annuum L., C. chinense L. and C. frutescens L., while morphologically distinguishable, are largely interfertile with one another and are commonly regarded forming a species complex [24]. These three sister cultigens, together with their conspecific wild populations, including C. annuum var. glabriusculum (Dunal) Heiser & Pickersgill, constitute the Capsicum annuum primary gene pool. The Capsicum baccatum primary gene pool is formed by the cultivated C. baccatum L. or more specifically C. baccatum var. pendulum (Willd.) Eshbaugh; its conspecific wild relative C. baccatum var. baccatum; and the more distantly related species, C. baccatum var. praetermissum (Heiser & P. G. Sm.) Hunz. Capsicum baccatum’s secondary gene pool consists of C. chacoense Hunz. The Capsicum pubescens primary gene pool is made up of the cultivated species (C. pubescens Ruiz & Pav.), together with the closely related purple-flowered wild species C. cardenasii Heiser & P. G. Sm. and C. eximium Hunz. [24], [25]. Several other wild edible species, C. eshbaughii Barboza and C. caballeroi Nee are recently discovered in Bolivia and resemble C. eximium and C. cardenasii in certain fruit and flower aspects, but their relativeness to C. pubescens still needs to be clarified [42], [54]. And so there are other wild species that require further analysis. The little-studied wild species Capsicum galapagoense Hunz. and C. tovarii Eshbaugh et al. have been suggested by some authors to form part of the C. annuum complex and C. baccatum gene pools, respectively, but are intentionally left out of this diagram until more conclusive evidence supporting their inclusion becomes available. The cultivated C. baccatum var. umbilicatum (Vell.) Hunz. & Barboza is not included until further evidence confirms its distinction from C. baccatum var. pendulum.
Fig 4.
Conceptual diagram showing the different steps followed in this study in the conservation of the necessary variation for selection, and evaluation and identification of promising accessions on the basis of diversity indicators as selection criteria.
Table 1.
Passport data of characterization and evaluation sites in Bolivia and Peru.
Table 2.
Variables and methods of measurement for biochemical characterization of Capsicum samples.
Fig 5.
The Peruvian and Bolivian collection sites.
Yellow dots refer to collection sites from the pre-existing accessions. Red dots refer to the sites where INIA (Peru) and CIFP (Bolivia) made complementary collections as part of this study.
Table 3.
Taxonomic identification of the CIFP and INIA Capsicum collections.
Table 4.
Biochemical fruit screening of the Capsicum accessions from the representative subsets.
Mean, minimum and maximum values are presented per species. In Peru, all accessions were grown in a common plot. In Bolivia, we anticipated that accessions were highly adapted to specific environments and were therefore grown in different locations.
Table 5.
Analysis of variance (ANOVA) per trait and significance levels for the effects ‘species’ and ‘location’ and their interaction expressed as mean squares.
Fig 6.
Box plots of trait values per species and per location.
Species: A = C. annuum (n = 4); B = C. baccatum (n = 7); C = C. chinense/ C. frutescens (n = 12). Locations: Ch = Chiclayo, P = Pucallpa, T = Tambo Grande. Significant differences between species or locations following the two-way ANOVA, are indicated with letters according to post-hoc Turkey’s Honest Significant Difference (HSD) tests with 95% confidence intervals.
Table 6.
Goodness to fit values of the correlations between environmental variance (S2) and mean trait (mi) values across accessions for each attribute.
Fig 7.
The first three components of a Principal Component Analysis (PCA) of the 23 promising Peruvian accessions.
Accessions are ordinated in response to the biochemical and agromorphological variation between them. Accessions are classified per species: A = C. annuum; B = C. baccatum; C = C. chinense; and F = C. frutescens; and are numbered by the six cluster groups defined by hierarchical clustering. Traits are indicated by abbreviations. ASTA = ASTA extractable color; Cap = capsaicinoids; Fat = fat; Flav = flavonoids; Quer = quercetin; Toc = tocopherols; Hght = Plant height; Flow = 50% plants set flowering; Wdth = fruit width; Wght = fruit weight. Polyphenols and antioxidant capacity score labels overlapped with capsaicinoid score labels and are therefore not shown. Fruit length score labels are not shown because they overlapped with fruit weight and width score labels.
Table 7.
Species and mean trait values per group after hierarchical clustering with Euclidian distances and Ward´s grouping method.