Summary
The genus Manihot, with around 120 known species, is native to a wide range of habitats and regions in the tropical and subtropical Americas. Its high species richness and recent ...diversification only c. 6 million years ago have significantly complicated previous phylogenetic analyses. Several basic elements of Manihot evolutionary history therefore remain unresolved.
Here, we conduct a comprehensive phylogenomic analysis of Manihot, focusing on exhaustive sampling of South American taxa.
We find that two recently described species from northeast Brazil's Atlantic Forest were the earliest to diverge, strongly suggesting a South American common ancestor of Manihot. Ancestral state reconstruction indicates early Manihot diversification in dry forests, with numerous independent episodes of new habitat colonization, including into savannas and rainforests within South America. We identify the closest wild relatives to Manihot esculenta, including the crop cassava, and we quantify extensive wild introgression into the cassava gene pool from at least five wild species, including Manihot glaziovii, a species used widely in breeding programs. Finally, we show that this wild‐to‐crop introgression substantially shapes the mutation load in cassava.
Our findings provide a detailed case study for neotropical evolutionary history in a diverse and widespread group, and a robust phylogenomic framework for future Manihot and cassava research.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
ABSTRACT Manihot includes about 150 species with a Neotropical distribution. Wild species of Manihot constitute a plant genetic heritage that can be used in breeding programs for the cultivable ...species Manihot esculenta Crantz (cassava). However, wild populations, especially endemic ones, are under constant threat due to habitat destruction and climate change. The objective of this manuscript was to elaborate a taxonomic treatment of the endemic species of Manihot recorded in Northeast Brazil; determine the geographical distribution of species, richness, their conservation status, and solve typification problems. The study was based on the analysis of specimens deposited in national and international herbaria, as well as on field observations. Fifteen endemic species of Manihot were found, we propose lectotypes for five of them and one neotype. Most species are distributed in the state of Bahia, growing in Caatinga, Cerrado, and Atlantic Forest environments. Only M. breviloba was found in the states of Sergipe and Alagoas. The richest area was found in the Chapada Diamantina of the Espinhaço Range. In terms of conservation status, 80% of endemic species are in some threatened category, 13% are in the near threatened category and only 7% are in the least concern category.
We describe and illustrate two species of Manihot that occur in Caatinga (semiarid) vegetation in Brazil and redescribe and lectotypify M. quinquefolia Pohl, which was only known from a single ...collection made by J. E. B. Pohl in 1827. Manihot elongata P.Carvalho & M.Martins is widely distributed and Manihot alterniflora P.Carvalho & M.Martins is endangered because of its small populations and restricted area of occurrence. We establish M. quinquefolia as the only species of Manihot in the Caatinga with compound leaves. An identification key is provided for the 13 species of Manihot present in the Caatinga.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
The leaf anatomy of nine species of Manihot Mill. has been studied with the objective of finding anatomical features that contribute to our understanding of the taxonomy of the genus. Leaf samples ...were collected in the field and from herbarium specimens, and standardized methods were used for both light and scanning electron microscopy (SEM). The following species were studied: M. bellidifolia P. Carvalho & M. Martins, M. brachyandra Pax & K. Hoffm., M. caerulescens Pohl, M. diamantinensis Allem, M. elongata sp. nov. ined., M. jacobinensis Müll. Arg. (I), M. jacobinensis Müll. Arg. (II), M. longiracemosa P. Carvalho & M. Martins, M. maracasensis Ule, M. reniformis Pohl, M. tripartita (Spreng) Müll. Arg. and Manihot sp. Anatomically, the analysis revealed differences that indicate the importance of leaf anatomy in the species‐level taxonomy. Presence of fibers in the bundle sheath, and presence or absence of papillae and fibers in the midrib are diagnostic characters. Although these characteristics were not enough to separate all of the species, or to group them into a section, they did show taxonomic importance at the species level. In addition, morphoanatomical differences and geographical distribution support Manihot sp. as a distinct species.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
The objective of this work was to evaluate the crossability between cassava (Manihot esculenta subsp. esculenta) cultivars and the subspecies M. esculenta subsp. flabellifolia and M. esculenta subsp. ...peruviana. Plants from the BRS Jari, BRS Formosa, BRS Verdinha, and BGM 2050 (Equador 72) cultivars were crossed with the two subspecies. During flowering, at pre-anthesis, pistillate flowers were covered with a nylon bag and staminate flowers on the same inflorescence were emasculated. The staminate flowers were collected and placed in flasks previously labeled and sterilized with alcohol; some fresh flowers were stored at room temperature due to asynchronous flowering. The crosses were made between 10 a.m. and 2 p.m. After pollination, the flowers were covered again. Evaluations were made from the moment of pollination to the dehiscence of the fruit. Of the total flowers pollinated, 38% were fertilized, and 504 developed fruits and 816 produced seeds were observed. As a male parent, M. esculenta subsp. flabellifolia is more efficient in crosses with M. esculenta subsp. esculenta and may be recommend for controlled crosses. The crosses between the cassava cultivars and M. esculenta subsp. flabellifolia and M. esculenta subsp. peruviana produce viable seeds.
Resumo: O objetivo deste trabalho foi avaliar o potencial de obtenção de híbridos oriundos do cruzamento de cultivares de mandioca (Manihot esculenta subsp. esculenta) com as subespécies M. esculenta subsp. flabellifolia e M. esculenta subsp. peruviana. Os cruzamentos foram realizados entre plantas das cultivares BRS Jari, BRS Formosa, BRS Verdinha e BGM 2050 (Equador 72) e das duas subespécies. Por ocasião do florescimento, no período pré-antese, as flores femininas foram cobertas com saco de pano tipo voal, com posterior emasculação das flores masculinas. As flores masculinas foram coletadas e acondicionadas em frascos previamente identificados e desinfetados com álcool; algumas flores foram armazenadas em temperatura ambiente devido ao florescimento assincrônico. Os cruzamentos foram feitos entre 10 e 14 horas. Após a polinização, as flores foram cobertas novamente. As avaliações foram efetuadas desde a polinização até a deiscência dos frutos. Do total das flores polinizadas, 38% foram fertilizadas, tendo-se observado 504 frutos desenvolvidos e 816 sementes produzidas. Manihot esculenta subsp. flabellifolia como parental masculino é mais eficiente em cruzamentos com M. esculenta subsp. esculenta e pode ser indicada para cruzamentos controlados. Os cruzamentos realizados entre as cultivares de mandioca e M. esculenta subsp. flabellifolia e M. esculenta subsp. peruviana propiciam a obtenção de sementes viáveis.
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•The young genus Manihot underwent recent, rapid diversification in the Neotropics.•Morphology, phylogenetics, and vegetation associations support three new species.•Manihot hahnii is ...a new species endemic of an ecotone in central Brazil.•Manihot carthagenensis underwent extensive admixture in Eastern South America.•Gene markers sts and ch_metE shed light into the evolutionary history of Manihot.
Intermittent episodes of climate changes, such as those that occurred during the Pleistocene, likely shaped the diversification of the young genus Manihot Mill. (Euphorbiacheae). One of such recently-derived congeners ─ M. carthagenensis ─ exhibits a widely disjunct distribution across dry environments in Eastern South America. Herein, we used molecular data from four nuclear gene regions (sts, ch_metE, g3pdh, and nia-i3) and seven nuclear microsatellite loci for reconstructing the phylogenetic relationships among M. carthagenensis and allied species and exploring likely phylogeographic scenarios that shaped the diversification and the distribution of gene pools of M. carthagenensis across the Caatinga and Chaco. Our data suggest that M. carthagenensis is not a monophyletic clade, as presently circumscribed. Morphological differences, genealogical relationships, and vegetation associations support three well-differentiated lineages, each of which merits the species rank: M. carthagenensis, M. glaziovii, and M. hahnii. Microsatellite data suggest that the newly circumscribed M. carthagenensis consists of at least three distinct gene pools, which are partly structured according to geography. The three gene pools likely evolved in allopatry, but remained interfertile. Population expansions after climate amelioration contributed to structuring hybrid zones. Moreover, we described two new single-copy gene regions (sts and ch_metE) as sources of molecular variation; they can facilitate the fine-scale probing of other parts of the phylogeny across Manihot.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Three species of Manihot Mill. from Brazil, M. decurrens M. Mend. & M. Martins, M. pandurata M. Mend. & M. Martins, and M. sagittata M. Mend. & M. Martins, are described and illustrated as new based ...on qualitative morphological characters observed from herbarium material, complemented with in situ observations of M. sagittata. Morphological characteristics of the new taxa, as well as morphological comparisons with closely related species and comments on natural distribution and ecological aspects, are provided.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Manihot cezarii M. Martins (Euphorbiaceae) is described and illustrated from the states of Goiás and Mato Grosso, Brazil. This species has flat, greenish blue leaves and pendent inflorescences with ...foliaceous bracts, characteristics that distinguish it from M. alutacea D. J. Rogers & Appan. The conservation status of the new species is assessed as Endangered (EN), according to IUCN Red List criteria.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
This study aimed to analyze the leaf anatomy of Manihot caerulescens, with emphasis on the ontogeny and secretion composition of the laticifers. Leaf samples were submitted the usual techniques in ...plant anatomy and histochemical tests to identify the main classes of secondary metabolites. The analyzes were performed using light and scanning electron microscopy. The leaves have a single layered epidermis coated by a uniform cuticle. The epidermal cells are elongated and papillose on the leaf abaxial surface of leaves. The mesophyll is isobilateral and the vascular bundle of the midrib is collateral. The laticifers are originated from ground meristem and procambium, and are of articulated anastomosing type. Besides the laticifers, two types of idioblasts were found: the secretory idioblasts, with a dense content, and the calcium oxalate druses idioblasts. Histochemical tests revealed different classes of chemicals for both secretory idioblasts and laticifers. In idioblasts, a positive reaction was detected for the general phenolic compounds, proteins, total polysaccharides and tannins. The laticifers reacted positively to total lipids and acids, essences, total polysaccharides and rubber. The individuals analyzed here are from caatinga and their leaf anatomical structure showed to be different from that described for the same species growing in the cerrado.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
This work aims to characterize the anatomy of leaves of wild
Manihot
species (Euphorbiaceae) and identify anatomical characteristics of taxonomic importance. Samples of
M. violacea
var.
...cecropiaefolia
,
M. violacea
var.
divergens
,
M. violacea
ssp.
jacobinensis
(Lençóis) and
M. violacea
were collected in
cerrado
(savanna), and samples of
M. violacea
ssp.
jacobinensis
and
M. violacea
ssp.
jacobinensis
(Mucugê) were collected in
campo rupestre
(rocky land) areas in northeastern Brazil. The leaf anatomy of these species was analyzed using optical and scanning electron microscopy in order to obtain useful characters for the taxonomy of the genus. Information acquired confirms the records from the literature for the genus. The taxonomic characters that were considered to be the most important are as follows: number of vascular bundles and petiole outline; distribution of secretory idioblasts; and presence of papillae and midrib outline. All of these species have secretory idioblasts, crystals, laticifers and isobilateral mesophyll. Most of the species present a cylindrical petiole outline. The number of vascular bundles on the petiole varies between five and ten. The similarity analysis reinforces
M. jacobinensis
as a distinct species.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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