José Valls - Academia.edu (original) (raw)
Papers by José Valls
Bonplandia
Estudios de compatibilidad cruzada en Arachis L. han sacado a la luz posibles nuevas fuentes de g... more Estudios de compatibilidad cruzada en Arachis L. han sacado a la luz posibles nuevas fuentes de genes para introgresión en el maní cultivado. Se hicieron un total de 32 cruzamientos distintos, utilizando A. gregoryi C.E. Simpson, Krapov. & Valls accesión V14957 como progenitor femenino y especies de Arachis que contienen siete genomas distintos como progenitores masculinos. Las 3167 polinizaciones resultaron en 153 híbridos inter e intraespecíficos confirmados. Estimaciones de viabilidad del polen paternal por tinción (PVS) variaron de 46.75 a 99.17%, mientras que el recuento de polen de los híbridos varió de 0.30 a 43.60 %, ese PVS más alto resultando de una combinación intraespecífica, lo que sugiere variabilidad apreciable entre accesiones de A. gregoryi. Las estimaciones de viabilidad del polen paterno por germinación (PVG) resultaron en valores consistentemente más bajos para todos los materiales, que van desde 41.91% a los 88.00%. Arachis gregoryi es importante para expandir l...
Bonplandia
Se describe una nueva especie brasileña de <em>Arachis</em> L. <em>Arachis veig... more Se describe una nueva especie brasileña de <em>Arachis</em> L. <em>Arachis veigae</em> S.H. Santana & Valls <em>nov. sp</em>, que presenta afinidad morfológica con <em>A. pusilla</em> Benth., se diferencia de ésta por la ausencia de un disco prominente en la base de los artejos del fruto y por presentar yemas cotiledonares no concaulescentes. Se discute la sinonimización de <em>A. sylvestris</em> (A. Chev.) A. Chev. y <em>A. pusilla</em>.
Bonplandia
In the original description of Arachis matiensis, two isolated populations, from the municipality... more In the original description of Arachis matiensis, two isolated populations, from the municipality of Cáceres, Mato Grosso State, Brazil, were listed as possibly representing a different species, but the analysis of additional materials, and further morphological study were considered necessary to reach a decision in that regard. New herbarium and germplasm collections in the area, additional morphological studies, and inter-and intraspecific crossing results now support the description of A. jacobinensis, a new species of the taxonomic section Procumbentes.
Annals of Botany, 2012
† Background and Aims The genus Arachis contains 80 described species. Section Arachis is of part... more † Background and Aims The genus Arachis contains 80 described species. Section Arachis is of particular interest because it includes cultivated peanut, an allotetraploid, and closely related wild species, most of which are diploids. This study aimed to analyse the genetic relationships of multiple accessions of section Arachis species using two complementary methods. Microsatellites allowed the analysis of inter-and intraspecific variability. Intron sequences from single-copy genes allowed phylogenetic analysis including the separation of the allotetraploid genome components. † Methods Intron sequences and microsatellite markers were used to reconstruct phylogenetic relationships in section Arachis through maximum parsimony and genetic distance analyses. † Key Results Although high intraspecific variability was evident, there was good support for most species. However, some problems were revealed, notably a probable polyphyletic origin for A. kuhlmannii. The validity of the genome groups was well supported. The F, K and D genomes grouped close to the A genome group. The 2n ¼ 18 species grouped closer to the B genome group. The phylogenetic tree based on the intron data strongly indicated that A. duranensis and A. ipaënsis are the ancestors of A. hypogaea and A. monticola. Intron nucleotide substitutions allowed the ages of divergences of the main genome groups to be estimated at a relatively recent 2. 3-2. 9 million years ago. This age and the number of species described indicate a much higher speciation rate for section Arachis than for legumes in general. † Conclusions The analyses revealed relationships between the species and genome groups and showed a generally high level of intraspecific genetic diversity. The improved knowledge of species relationships should facilitate the utilization of wild species for peanut improvement. The estimates of speciation rates in section Arachis are high, but not unprecedented. We suggest these high rates may be linked to the peculiar reproductive biology of Arachis.
Phytotaxa, 2015
Paspalum chilense, a new species from Chile belonging to the informal Notata group, is described ... more Paspalum chilense, a new species from Chile belonging to the informal Notata group, is described and illustrated on the basis of morphological, cytological and molecular evidence. Our evidence supports its affinity with P. barretoi and P. nummularium, from Brazil, from which it probably diverged by vicariant speciation. The limited available material of the new species was previously identified as P. pumilum or P. minus. A new key to the species of the core Notata group is provided.
† Background and Aims The genus Arachis contains 80 described species. Section Arachis is of part... more † Background and Aims The genus Arachis contains 80 described species. Section Arachis is of particular interest because it includes cultivated peanut, an allotetraploid, and closely related wild species, most of which are diploids. This study aimed to analyse the genetic relationships of multiple accessions of section Arachis species using two complementary methods. Microsatellites allowed the analysis of inter-and intraspecific variability. Intron sequences from single-copy genes allowed phylogenetic analysis including the separation of the allotetraploid genome components. † Methods Intron sequences and microsatellite markers were used to reconstruct phylogenetic relationships in section Arachis through maximum parsimony and genetic distance analyses. † Key Results Although high intraspecific variability was evident, there was good support for most species. However, some problems were revealed, notably a probable polyphyletic origin for A. kuhlmannii. The validity of the genome groups was well supported. The F, K and D genomes grouped close to the A genome group. The 2n ¼ 18 species grouped closer to the B genome group. The phylogenetic tree based on the intron data strongly indicated that A. duranensis and A. ipaënsis are the ancestors of A. hypogaea and A. monticola. Intron nucleotide substitutions allowed the ages of divergences of the main genome groups to be estimated at a relatively recent 2. 3-2. 9 million years ago. This age and the number of species described indicate a much higher speciation rate for section Arachis than for legumes in general. † Conclusions The analyses revealed relationships between the species and genome groups and showed a generally high level of intraspecific genetic diversity. The improved knowledge of species relationships should facilitate the utilization of wild species for peanut improvement. The estimates of speciation rates in section Arachis are high, but not unprecedented. We suggest these high rates may be linked to the peculiar reproductive biology of Arachis.
Cryo letters
The effects of two methods of cryopreservation involving chemical vitrification and air desiccati... more The effects of two methods of cryopreservation involving chemical vitrification and air desiccation) were studied on isolated embryonic axes of A. hypogaea. Vitrification with PVS2 and desiccation in a laminar flow cabinet resulted in high levels (70-90%) of whole plant recovery after cryopreservation. A desiccation protocol based on 1h exposure of explants to the air flow was successfully applied to six wild species of section Extranervosae, resulting in recovery levels of 70-90% after liquid nitrogen treatment.
Cryo letters
A storage protocol at cryogenic temperature was established for shoot apices from in vitro plants... more A storage protocol at cryogenic temperature was established for shoot apices from in vitro plants of the cultivated groundnut (Arachis hypogaea) and wild Arachis species (A. retusa and A. burchellii) using a basic vitrification protocol with direct immersion in liquid nitrogen (LN). The effect of pre-treatments of donor-plants with ABA as well as of different supplements in the post-thaw culture medium was studied. After rapid warming at 40 C, the explants were cultured on MS medium devoid of growth regulators (MS0) or MS supplemented with 4.4(M benzylaminopurine (BAP) and 0.5(M naphthalene acetic acid (NAA) plus 5(M silver nitrate (AgNO3), 0.25% polyvinylpyrrolidone (PVP) or 0.2% activated charcoal. Non-frozen explants from the three species formed one shoot through meristematic amplification when cultured on MS0 medium. These explants also developed callus on MS supplemented with growth regulators (4.4(M BAP and 0.5(M NAA) alone or plus PVP or AgNO3. Callus formation was suppresse...
Annals of Botany, 2005
Background and Aims The Quadrifaria group of Paspalum (Poaceae, Paniceae) comprises species nativ... more Background and Aims The Quadrifaria group of Paspalum (Poaceae, Paniceae) comprises species native to the subtropical and temperate regions of South America. The purpose of this research was to characterize the I genomes in five species of this group and to establish phylogenetic relationships among them. Methods Prometaphase chromatin condensation patterns, the physical location of 5S and 45S rDNA sites by fluorescence in situ hybridization (FISH), and sequences of five chloroplast non-coding regions were analysed. Key Results The condensation patterns observed were highly conserved among diploid and tetraploid accessions studied and not influenced by the dyes used or by the FISH procedure, allowing the identification of almost all the chromosome pairs that carried the rDNA signals. The FISH analysis of 5S rDNA sites showed the same localization and a correspondence between the number of sites and ploidy level. In contrast, the distribution of 45S rDNA sites was variable. Two general patterns were observed with respect to the location of the 45S rDNA. The species and cytotypes Paspalum haumanii 2x, P. intermedium 2x, P. quadrifarium 4x and P. exaltatum 4x showed proximal sites on chromosome 8 and two to four distal sites in other chromosomes, while P. quarinii 4x and P. quadrifarium 2x showed only distal sites located on a variable number of small chromosomes and on the long arm of chromosome 1. The single most-parsimonious tree found from the phylogenetic analysis showed the Quadrifaria species partitioned in two clades, one of them includes P. haumanii 2x and P. intermedium 2x together with P. quadrifarium 4x and P. exaltatum 4x, while the other contains P. quadrifarium 2x and P. quarinii 4x. Conclusions The subdivision found with FISH is consistent with the clades recovered with cpDNA data and both analyses suggest that the Quadrifaria group, as presently defined, is not monophyletic and its species belong in at least two clades.
Plant Genetic Resources, 2011
The legumeArachis hypogaea, commonly known as peanut or groundnut, is a very important food crop ... more The legumeArachis hypogaea, commonly known as peanut or groundnut, is a very important food crop throughout the tropics and sub-tropics. The genus is endemic to South America being mostly associated with the savannah-like Cerrado. All species in the genus are unusual among legumes in that they produce their fruit below the ground. This profoundly influences their biology and natural distributions. The species occur in diverse habitats including grasslands, open patches of forest and even in temporarily flooded areas. Based on a number of criteria, including morphology and sexual compatibilities, the 80 described species are arranged in nine infrageneric taxonomic sections. While most wild species are diploid, cultivated peanut is a tetraploid. It is of recent origin and has an AABB-type genome. The most probable ancestral species areArachis duranensisandArachis ipaënsis, which contributed the A and B genome components, respectively. Although cultivated peanut is tetraploid, genetica...
Plant Cell, Tissue and Organ Culture, 2007
Somatic embryogenesis was induced from seed explants of Arachis archeri, A. porphyrocalix (Sectio... more Somatic embryogenesis was induced from seed explants of Arachis archeri, A. porphyrocalix (Section Erectoides) and A. appressipila (Section Procumbentes) in response to 6-benzylaminopurine (BAP). Embryo axes first developed into single shoots in response to 4.4 lM BAP. Friable embryogenic calluses were produced from the hypocotyl region of these explants in response to different BAP concentrations. Embryonic leaflets also gave rise to friable calluses, but somatic embryos were only observed in explants of A. archeri and A. appressipila. Histological analyses revealed the presence of heart-shaped, torpedo and cotyledonary stages embryos, both as isolated and fused structures. A low frequency of embryo-to-plant conversion was achieved by inducing shoot development on medium solidified with 0.5% phytagel and supplemented with 1.5% or 3% sucrose. Rooting was induced on MS supplemented with indole-3acetic acid (IAA).
Pesquisa Agropecuária Brasileira, 2004
In vitro regeneration of Arachis retusa was examined for the purpose of germplasm renewal and con... more In vitro regeneration of Arachis retusa was examined for the purpose of germplasm renewal and conservation. Random amplified polymorphic DNA (RAPD) fingerprinting was used to evaluate the genetic stability of plants derived from embryo axes and apical segments. Ten arbitrary decamer primers were screened and five of them were selected. Ninety genomic regions were evaluated, with an average of 18 loci per clone. All amplified segments were monomorphic. The results indicate that recovered plants are genetically stable at the assessed genomic regions and that both regeneration processes are suitable for in vitro germplasm preservation of Arachis species.
Pesquisa Agropecuária Brasileira, 2006
The objective of this work was to evaluate the influence of substrate and preconditioning treatme... more The objective of this work was to evaluate the influence of substrate and preconditioning treatments on the acclimatization of in vitro plants of Arachis retusa. Plants were transferred to Plantmax or sand, and fertilized with Hoagland's nutrient solution. Plants maintained in sand, with or without fertilizer, showed the highest survival rates. In order to evaluate the influence of in vitro preconditioning treatments, stem segments were cultured on MS medium supplemented with different sucrose concentrations. The highest survival and developmental rates were observed in plants from two accessions cultured on MS supplemented with 1.5% and 3% sucrose. Flowering and fruit production were observed after five months.
In Vitro Cellular & Developmental Biology - Plant, 2008
Seed explants of A. stenosperma were cultured on MS medium supplemented with 6-benzylaminopurine ... more Seed explants of A. stenosperma were cultured on MS medium supplemented with 6-benzylaminopurine with the aim of rescuing nonviable accessions stored in seed bank conditions. The regeneration potential of leaf explants from in vitro plants derived from embryonic axes was studied by using whole leaflets and leaflet segments. Explants were cultured on Murashige and Skoog (MS) medium supplemented with different concentrations of 6-benzylaminopurine and naphthalene acetic acid. Indirect organogenesis was observed in response to 6-benzylaminopurine, either alone or in association with naphthalene acetic acid, in both explant types. Media supplemented with naphthalene acetic acid as the sole growth regulator induced rhizogenesis in whole leaflets and leaflet segments, with subsequent shoot production directly from the roots.
Genome, 1998
Genetic variation within and among accessions of the genusArachis representing sections Extranerv... more Genetic variation within and among accessions of the genusArachis representing sections Extranervosae, Caulorrhizae, Heteranthae, and Triseminatae was evaluated using RFLP and RAPD markers. RAPD markers revealed a higher level of genetic diversity than did RFLP markers, both within and among the species evaluated. Phenograms based on various band-matching algorithms revealed three major clusters of similarity among the sections evaluated. The first group included the species from section Extranervosae, the second group consisted of sections Triseminatae, Caulorrhizae, and Heteranthae, and the third group consisted of one accession of Arachis hypogaea, which had been included as a representative of section Arachis. The phenogramsobtained from the RAPD and RFLP data were similar but not identical. Arachis pietrarellii, assayed only by RAPD, showed a high degree of genetic similarity with Arachis villosulicarpa. This observation supported the hypothesis that these two species are close...
Genetics and Molecular Biology, 2000
Mode of reproduction was studied in 15 species of Adesmia DC. (Leguminosae). In six species, thre... more Mode of reproduction was studied in 15 species of Adesmia DC. (Leguminosae). In six species, three treatments were used: mutual pollination, mechanical stimulation and control. Fifty-four plants of these six species were grown in a greenhouse, individually isolated in nylon screen boxes. Flowers were labelled and submitted to the different treatments. In addition, the frequency of spontaneous self-pollination in the absence of pollinators was studied in 200 plants of nine other species. These 200 plants were kept in a greenhouse, which avoided contact with any possible pollinator. Adesmia bicolor, A. muricata, A. punctata and A. riograndensis produced seed both by cross- and self-pollination. Adesmia punctata and A. riograndensis need mechanical stimulation for self-pollination. Adesmia incana reproduced by self-pollination; however, the possibility of cross-pollination cannot be totally ruled out. Adesmia tristis reproduced mainly by cross-pollination and a mechanism of self-incomp...
Genetica, 2006
The present work intends to clarify the phylogenetic relationships among the species of Paspalum ... more The present work intends to clarify the phylogenetic relationships among the species of Paspalum L. belonging to the informal groups Notata/Linearia and Dilatata, and to raise some preliminary hypotheses on the phylogeny of the genus as a whole. A combined dataset including morphological and molecular characters was used to analyze 28 species of Paspalum plus some representatives of related genera of the tribe Paniceae. Analyses were performed using both parsimony and maximum likelihood. The monophyly of Paspalum is not supported nor contradicted. The circumscription of informal groups of Paspalum is discussed, as well as the cladistic treatment of allopolyploid taxa, especially those comprising the Dilatata group. The relationships of members of the Dilatata with their putative progenitors is confirmed, but the monophyly of the group as a whole is not. A close relationship between P. dilatatum Poir. and P. lividum Trin. ex Schltdl. is shown. Our analysis is consistent with the monophyly of a group comprising Notata+Linearia, with a monophyletic Notata group nested within it. The delimitation of the core Notata is proposed by including P. conduplicatum Canto-Dorow, Valls and Longhi-Wagner, P. notatum Flu¨gge´, P. minus E. Fourn., P. pumilum Nees and P. subciliatum Chase.
Flora - Morphology, Distribution, Functional Ecology of Plants, 2008
The subgenus Anachyris of the genus Paspalum comprises six species, all native to the New World. ... more The subgenus Anachyris of the genus Paspalum comprises six species, all native to the New World. Cytology, embryology, fertility, and hybridization experiments were examined in four of the six species and different chromosome races. Meiotic chromosome behavior supported autoploid origin for tetraploid P. procurrens and tetraploid P. usterii, and also corroborates autoploidy for P. malacophyllum. Meiosis of the three species was compared with the meiotic chromosome behavior of a tetraploid P. simplex strain acquired by artificial autopolyploidization. Moreover, chromosome associations observed in tetraploid interspecific hybrids of P. simplex  procurrens and P. simplex  usterii, in triploid hybrids of P. simplex  malacophyllum, and in diploid hybrids of P. simplex  malacophyllum, indicate that the four species share the same basic genome, and that the polyploid races are autoploids. Facultative apomixis of the aposporous type is reported for the first time in tetraploid strains of P. procurrens and P. usterii. It is also confirmed for tetraploid P. malacophyllum, a species whose diploid representative is here reported to reproduce sexually, though embryological analyses demonstrated some potential for apospory. Our results suggest that the whole subgenus Anachyris of Paspalum is basically an agamic complex. At least three species: P. simplex, P. procurrens, and P. malacophyllum involve sexual self-incompatible diploid races as well as apomictic polyploid (mainly tetraploid) representatives.
Plant Genetic …, 2011
The legume Arachis hypogaea, commonly known as peanut or groundnut, is a very important food crop... more The legume Arachis hypogaea, commonly known as peanut or groundnut, is a very important food crop throughout the tropics and sub-tropics. The genus is endemic to South America being mostly associated with the savannah-like Cerrado. All species in the genus are unusual among legumes in that they produce their fruit below the ground. This profoundly influences their biology and natural distributions. The species occur in diverse habitats including grasslands, open patches of forest and even in temporarily flooded areas. Based on a number of criteria, including morphology and sexual compatibilities, the 80 described species are arranged in nine infrageneric taxonomic sections. While most wild species are diploid, cultivated peanut is a tetraploid. It is of recent origin and has an AABB-type genome. The most probable ancestral species are Arachis duranensis and Arachis ipaënsis, which contributed the A and B genome components, respectively. Although cultivated peanut is tetraploid, genetically it behaves as a diploid, the A and B chromosomes only rarely pairing during meiosis. Although morphologically variable, cultivated peanut has a very narrow genetic base. For some traits, such as disease and pest resistance, this has been a fundamental limitation to crop improvement using only cultivated germplasm. Transfer of some wild resistance genes to cultivated peanut has been achieved, for instance, the gene for resistance to root-knot nematode. However, a wider use of wild species in breeding has been hampered by ploidy and sexual incompatibility barriers, by linkage drag, and historically, by a lack of the tools needed to conveniently confirm hybrid identities and track introgressed chromosomal segments. In recent years, improved knowledge of species relationships has been gained by more detailed cytogenetic studies and molecular phylogenies. This knowledge, together with new tools for genetic and genomic analysis, will help in the more efficient use of peanut's genetic resources in crop improvement.
Bonplandia
Estudios de compatibilidad cruzada en Arachis L. han sacado a la luz posibles nuevas fuentes de g... more Estudios de compatibilidad cruzada en Arachis L. han sacado a la luz posibles nuevas fuentes de genes para introgresión en el maní cultivado. Se hicieron un total de 32 cruzamientos distintos, utilizando A. gregoryi C.E. Simpson, Krapov. & Valls accesión V14957 como progenitor femenino y especies de Arachis que contienen siete genomas distintos como progenitores masculinos. Las 3167 polinizaciones resultaron en 153 híbridos inter e intraespecíficos confirmados. Estimaciones de viabilidad del polen paternal por tinción (PVS) variaron de 46.75 a 99.17%, mientras que el recuento de polen de los híbridos varió de 0.30 a 43.60 %, ese PVS más alto resultando de una combinación intraespecífica, lo que sugiere variabilidad apreciable entre accesiones de A. gregoryi. Las estimaciones de viabilidad del polen paterno por germinación (PVG) resultaron en valores consistentemente más bajos para todos los materiales, que van desde 41.91% a los 88.00%. Arachis gregoryi es importante para expandir l...
Bonplandia
Se describe una nueva especie brasileña de <em>Arachis</em> L. <em>Arachis veig... more Se describe una nueva especie brasileña de <em>Arachis</em> L. <em>Arachis veigae</em> S.H. Santana & Valls <em>nov. sp</em>, que presenta afinidad morfológica con <em>A. pusilla</em> Benth., se diferencia de ésta por la ausencia de un disco prominente en la base de los artejos del fruto y por presentar yemas cotiledonares no concaulescentes. Se discute la sinonimización de <em>A. sylvestris</em> (A. Chev.) A. Chev. y <em>A. pusilla</em>.
Bonplandia
In the original description of Arachis matiensis, two isolated populations, from the municipality... more In the original description of Arachis matiensis, two isolated populations, from the municipality of Cáceres, Mato Grosso State, Brazil, were listed as possibly representing a different species, but the analysis of additional materials, and further morphological study were considered necessary to reach a decision in that regard. New herbarium and germplasm collections in the area, additional morphological studies, and inter-and intraspecific crossing results now support the description of A. jacobinensis, a new species of the taxonomic section Procumbentes.
Annals of Botany, 2012
† Background and Aims The genus Arachis contains 80 described species. Section Arachis is of part... more † Background and Aims The genus Arachis contains 80 described species. Section Arachis is of particular interest because it includes cultivated peanut, an allotetraploid, and closely related wild species, most of which are diploids. This study aimed to analyse the genetic relationships of multiple accessions of section Arachis species using two complementary methods. Microsatellites allowed the analysis of inter-and intraspecific variability. Intron sequences from single-copy genes allowed phylogenetic analysis including the separation of the allotetraploid genome components. † Methods Intron sequences and microsatellite markers were used to reconstruct phylogenetic relationships in section Arachis through maximum parsimony and genetic distance analyses. † Key Results Although high intraspecific variability was evident, there was good support for most species. However, some problems were revealed, notably a probable polyphyletic origin for A. kuhlmannii. The validity of the genome groups was well supported. The F, K and D genomes grouped close to the A genome group. The 2n ¼ 18 species grouped closer to the B genome group. The phylogenetic tree based on the intron data strongly indicated that A. duranensis and A. ipaënsis are the ancestors of A. hypogaea and A. monticola. Intron nucleotide substitutions allowed the ages of divergences of the main genome groups to be estimated at a relatively recent 2. 3-2. 9 million years ago. This age and the number of species described indicate a much higher speciation rate for section Arachis than for legumes in general. † Conclusions The analyses revealed relationships between the species and genome groups and showed a generally high level of intraspecific genetic diversity. The improved knowledge of species relationships should facilitate the utilization of wild species for peanut improvement. The estimates of speciation rates in section Arachis are high, but not unprecedented. We suggest these high rates may be linked to the peculiar reproductive biology of Arachis.
Phytotaxa, 2015
Paspalum chilense, a new species from Chile belonging to the informal Notata group, is described ... more Paspalum chilense, a new species from Chile belonging to the informal Notata group, is described and illustrated on the basis of morphological, cytological and molecular evidence. Our evidence supports its affinity with P. barretoi and P. nummularium, from Brazil, from which it probably diverged by vicariant speciation. The limited available material of the new species was previously identified as P. pumilum or P. minus. A new key to the species of the core Notata group is provided.
† Background and Aims The genus Arachis contains 80 described species. Section Arachis is of part... more † Background and Aims The genus Arachis contains 80 described species. Section Arachis is of particular interest because it includes cultivated peanut, an allotetraploid, and closely related wild species, most of which are diploids. This study aimed to analyse the genetic relationships of multiple accessions of section Arachis species using two complementary methods. Microsatellites allowed the analysis of inter-and intraspecific variability. Intron sequences from single-copy genes allowed phylogenetic analysis including the separation of the allotetraploid genome components. † Methods Intron sequences and microsatellite markers were used to reconstruct phylogenetic relationships in section Arachis through maximum parsimony and genetic distance analyses. † Key Results Although high intraspecific variability was evident, there was good support for most species. However, some problems were revealed, notably a probable polyphyletic origin for A. kuhlmannii. The validity of the genome groups was well supported. The F, K and D genomes grouped close to the A genome group. The 2n ¼ 18 species grouped closer to the B genome group. The phylogenetic tree based on the intron data strongly indicated that A. duranensis and A. ipaënsis are the ancestors of A. hypogaea and A. monticola. Intron nucleotide substitutions allowed the ages of divergences of the main genome groups to be estimated at a relatively recent 2. 3-2. 9 million years ago. This age and the number of species described indicate a much higher speciation rate for section Arachis than for legumes in general. † Conclusions The analyses revealed relationships between the species and genome groups and showed a generally high level of intraspecific genetic diversity. The improved knowledge of species relationships should facilitate the utilization of wild species for peanut improvement. The estimates of speciation rates in section Arachis are high, but not unprecedented. We suggest these high rates may be linked to the peculiar reproductive biology of Arachis.
Cryo letters
The effects of two methods of cryopreservation involving chemical vitrification and air desiccati... more The effects of two methods of cryopreservation involving chemical vitrification and air desiccation) were studied on isolated embryonic axes of A. hypogaea. Vitrification with PVS2 and desiccation in a laminar flow cabinet resulted in high levels (70-90%) of whole plant recovery after cryopreservation. A desiccation protocol based on 1h exposure of explants to the air flow was successfully applied to six wild species of section Extranervosae, resulting in recovery levels of 70-90% after liquid nitrogen treatment.
Cryo letters
A storage protocol at cryogenic temperature was established for shoot apices from in vitro plants... more A storage protocol at cryogenic temperature was established for shoot apices from in vitro plants of the cultivated groundnut (Arachis hypogaea) and wild Arachis species (A. retusa and A. burchellii) using a basic vitrification protocol with direct immersion in liquid nitrogen (LN). The effect of pre-treatments of donor-plants with ABA as well as of different supplements in the post-thaw culture medium was studied. After rapid warming at 40 C, the explants were cultured on MS medium devoid of growth regulators (MS0) or MS supplemented with 4.4(M benzylaminopurine (BAP) and 0.5(M naphthalene acetic acid (NAA) plus 5(M silver nitrate (AgNO3), 0.25% polyvinylpyrrolidone (PVP) or 0.2% activated charcoal. Non-frozen explants from the three species formed one shoot through meristematic amplification when cultured on MS0 medium. These explants also developed callus on MS supplemented with growth regulators (4.4(M BAP and 0.5(M NAA) alone or plus PVP or AgNO3. Callus formation was suppresse...
Annals of Botany, 2005
Background and Aims The Quadrifaria group of Paspalum (Poaceae, Paniceae) comprises species nativ... more Background and Aims The Quadrifaria group of Paspalum (Poaceae, Paniceae) comprises species native to the subtropical and temperate regions of South America. The purpose of this research was to characterize the I genomes in five species of this group and to establish phylogenetic relationships among them. Methods Prometaphase chromatin condensation patterns, the physical location of 5S and 45S rDNA sites by fluorescence in situ hybridization (FISH), and sequences of five chloroplast non-coding regions were analysed. Key Results The condensation patterns observed were highly conserved among diploid and tetraploid accessions studied and not influenced by the dyes used or by the FISH procedure, allowing the identification of almost all the chromosome pairs that carried the rDNA signals. The FISH analysis of 5S rDNA sites showed the same localization and a correspondence between the number of sites and ploidy level. In contrast, the distribution of 45S rDNA sites was variable. Two general patterns were observed with respect to the location of the 45S rDNA. The species and cytotypes Paspalum haumanii 2x, P. intermedium 2x, P. quadrifarium 4x and P. exaltatum 4x showed proximal sites on chromosome 8 and two to four distal sites in other chromosomes, while P. quarinii 4x and P. quadrifarium 2x showed only distal sites located on a variable number of small chromosomes and on the long arm of chromosome 1. The single most-parsimonious tree found from the phylogenetic analysis showed the Quadrifaria species partitioned in two clades, one of them includes P. haumanii 2x and P. intermedium 2x together with P. quadrifarium 4x and P. exaltatum 4x, while the other contains P. quadrifarium 2x and P. quarinii 4x. Conclusions The subdivision found with FISH is consistent with the clades recovered with cpDNA data and both analyses suggest that the Quadrifaria group, as presently defined, is not monophyletic and its species belong in at least two clades.
Plant Genetic Resources, 2011
The legumeArachis hypogaea, commonly known as peanut or groundnut, is a very important food crop ... more The legumeArachis hypogaea, commonly known as peanut or groundnut, is a very important food crop throughout the tropics and sub-tropics. The genus is endemic to South America being mostly associated with the savannah-like Cerrado. All species in the genus are unusual among legumes in that they produce their fruit below the ground. This profoundly influences their biology and natural distributions. The species occur in diverse habitats including grasslands, open patches of forest and even in temporarily flooded areas. Based on a number of criteria, including morphology and sexual compatibilities, the 80 described species are arranged in nine infrageneric taxonomic sections. While most wild species are diploid, cultivated peanut is a tetraploid. It is of recent origin and has an AABB-type genome. The most probable ancestral species areArachis duranensisandArachis ipaënsis, which contributed the A and B genome components, respectively. Although cultivated peanut is tetraploid, genetica...
Plant Cell, Tissue and Organ Culture, 2007
Somatic embryogenesis was induced from seed explants of Arachis archeri, A. porphyrocalix (Sectio... more Somatic embryogenesis was induced from seed explants of Arachis archeri, A. porphyrocalix (Section Erectoides) and A. appressipila (Section Procumbentes) in response to 6-benzylaminopurine (BAP). Embryo axes first developed into single shoots in response to 4.4 lM BAP. Friable embryogenic calluses were produced from the hypocotyl region of these explants in response to different BAP concentrations. Embryonic leaflets also gave rise to friable calluses, but somatic embryos were only observed in explants of A. archeri and A. appressipila. Histological analyses revealed the presence of heart-shaped, torpedo and cotyledonary stages embryos, both as isolated and fused structures. A low frequency of embryo-to-plant conversion was achieved by inducing shoot development on medium solidified with 0.5% phytagel and supplemented with 1.5% or 3% sucrose. Rooting was induced on MS supplemented with indole-3acetic acid (IAA).
Pesquisa Agropecuária Brasileira, 2004
In vitro regeneration of Arachis retusa was examined for the purpose of germplasm renewal and con... more In vitro regeneration of Arachis retusa was examined for the purpose of germplasm renewal and conservation. Random amplified polymorphic DNA (RAPD) fingerprinting was used to evaluate the genetic stability of plants derived from embryo axes and apical segments. Ten arbitrary decamer primers were screened and five of them were selected. Ninety genomic regions were evaluated, with an average of 18 loci per clone. All amplified segments were monomorphic. The results indicate that recovered plants are genetically stable at the assessed genomic regions and that both regeneration processes are suitable for in vitro germplasm preservation of Arachis species.
Pesquisa Agropecuária Brasileira, 2006
The objective of this work was to evaluate the influence of substrate and preconditioning treatme... more The objective of this work was to evaluate the influence of substrate and preconditioning treatments on the acclimatization of in vitro plants of Arachis retusa. Plants were transferred to Plantmax or sand, and fertilized with Hoagland's nutrient solution. Plants maintained in sand, with or without fertilizer, showed the highest survival rates. In order to evaluate the influence of in vitro preconditioning treatments, stem segments were cultured on MS medium supplemented with different sucrose concentrations. The highest survival and developmental rates were observed in plants from two accessions cultured on MS supplemented with 1.5% and 3% sucrose. Flowering and fruit production were observed after five months.
In Vitro Cellular & Developmental Biology - Plant, 2008
Seed explants of A. stenosperma were cultured on MS medium supplemented with 6-benzylaminopurine ... more Seed explants of A. stenosperma were cultured on MS medium supplemented with 6-benzylaminopurine with the aim of rescuing nonviable accessions stored in seed bank conditions. The regeneration potential of leaf explants from in vitro plants derived from embryonic axes was studied by using whole leaflets and leaflet segments. Explants were cultured on Murashige and Skoog (MS) medium supplemented with different concentrations of 6-benzylaminopurine and naphthalene acetic acid. Indirect organogenesis was observed in response to 6-benzylaminopurine, either alone or in association with naphthalene acetic acid, in both explant types. Media supplemented with naphthalene acetic acid as the sole growth regulator induced rhizogenesis in whole leaflets and leaflet segments, with subsequent shoot production directly from the roots.
Genome, 1998
Genetic variation within and among accessions of the genusArachis representing sections Extranerv... more Genetic variation within and among accessions of the genusArachis representing sections Extranervosae, Caulorrhizae, Heteranthae, and Triseminatae was evaluated using RFLP and RAPD markers. RAPD markers revealed a higher level of genetic diversity than did RFLP markers, both within and among the species evaluated. Phenograms based on various band-matching algorithms revealed three major clusters of similarity among the sections evaluated. The first group included the species from section Extranervosae, the second group consisted of sections Triseminatae, Caulorrhizae, and Heteranthae, and the third group consisted of one accession of Arachis hypogaea, which had been included as a representative of section Arachis. The phenogramsobtained from the RAPD and RFLP data were similar but not identical. Arachis pietrarellii, assayed only by RAPD, showed a high degree of genetic similarity with Arachis villosulicarpa. This observation supported the hypothesis that these two species are close...
Genetics and Molecular Biology, 2000
Mode of reproduction was studied in 15 species of Adesmia DC. (Leguminosae). In six species, thre... more Mode of reproduction was studied in 15 species of Adesmia DC. (Leguminosae). In six species, three treatments were used: mutual pollination, mechanical stimulation and control. Fifty-four plants of these six species were grown in a greenhouse, individually isolated in nylon screen boxes. Flowers were labelled and submitted to the different treatments. In addition, the frequency of spontaneous self-pollination in the absence of pollinators was studied in 200 plants of nine other species. These 200 plants were kept in a greenhouse, which avoided contact with any possible pollinator. Adesmia bicolor, A. muricata, A. punctata and A. riograndensis produced seed both by cross- and self-pollination. Adesmia punctata and A. riograndensis need mechanical stimulation for self-pollination. Adesmia incana reproduced by self-pollination; however, the possibility of cross-pollination cannot be totally ruled out. Adesmia tristis reproduced mainly by cross-pollination and a mechanism of self-incomp...
Genetica, 2006
The present work intends to clarify the phylogenetic relationships among the species of Paspalum ... more The present work intends to clarify the phylogenetic relationships among the species of Paspalum L. belonging to the informal groups Notata/Linearia and Dilatata, and to raise some preliminary hypotheses on the phylogeny of the genus as a whole. A combined dataset including morphological and molecular characters was used to analyze 28 species of Paspalum plus some representatives of related genera of the tribe Paniceae. Analyses were performed using both parsimony and maximum likelihood. The monophyly of Paspalum is not supported nor contradicted. The circumscription of informal groups of Paspalum is discussed, as well as the cladistic treatment of allopolyploid taxa, especially those comprising the Dilatata group. The relationships of members of the Dilatata with their putative progenitors is confirmed, but the monophyly of the group as a whole is not. A close relationship between P. dilatatum Poir. and P. lividum Trin. ex Schltdl. is shown. Our analysis is consistent with the monophyly of a group comprising Notata+Linearia, with a monophyletic Notata group nested within it. The delimitation of the core Notata is proposed by including P. conduplicatum Canto-Dorow, Valls and Longhi-Wagner, P. notatum Flu¨gge´, P. minus E. Fourn., P. pumilum Nees and P. subciliatum Chase.
Flora - Morphology, Distribution, Functional Ecology of Plants, 2008
The subgenus Anachyris of the genus Paspalum comprises six species, all native to the New World. ... more The subgenus Anachyris of the genus Paspalum comprises six species, all native to the New World. Cytology, embryology, fertility, and hybridization experiments were examined in four of the six species and different chromosome races. Meiotic chromosome behavior supported autoploid origin for tetraploid P. procurrens and tetraploid P. usterii, and also corroborates autoploidy for P. malacophyllum. Meiosis of the three species was compared with the meiotic chromosome behavior of a tetraploid P. simplex strain acquired by artificial autopolyploidization. Moreover, chromosome associations observed in tetraploid interspecific hybrids of P. simplex  procurrens and P. simplex  usterii, in triploid hybrids of P. simplex  malacophyllum, and in diploid hybrids of P. simplex  malacophyllum, indicate that the four species share the same basic genome, and that the polyploid races are autoploids. Facultative apomixis of the aposporous type is reported for the first time in tetraploid strains of P. procurrens and P. usterii. It is also confirmed for tetraploid P. malacophyllum, a species whose diploid representative is here reported to reproduce sexually, though embryological analyses demonstrated some potential for apospory. Our results suggest that the whole subgenus Anachyris of Paspalum is basically an agamic complex. At least three species: P. simplex, P. procurrens, and P. malacophyllum involve sexual self-incompatible diploid races as well as apomictic polyploid (mainly tetraploid) representatives.
Plant Genetic …, 2011
The legume Arachis hypogaea, commonly known as peanut or groundnut, is a very important food crop... more The legume Arachis hypogaea, commonly known as peanut or groundnut, is a very important food crop throughout the tropics and sub-tropics. The genus is endemic to South America being mostly associated with the savannah-like Cerrado. All species in the genus are unusual among legumes in that they produce their fruit below the ground. This profoundly influences their biology and natural distributions. The species occur in diverse habitats including grasslands, open patches of forest and even in temporarily flooded areas. Based on a number of criteria, including morphology and sexual compatibilities, the 80 described species are arranged in nine infrageneric taxonomic sections. While most wild species are diploid, cultivated peanut is a tetraploid. It is of recent origin and has an AABB-type genome. The most probable ancestral species are Arachis duranensis and Arachis ipaënsis, which contributed the A and B genome components, respectively. Although cultivated peanut is tetraploid, genetically it behaves as a diploid, the A and B chromosomes only rarely pairing during meiosis. Although morphologically variable, cultivated peanut has a very narrow genetic base. For some traits, such as disease and pest resistance, this has been a fundamental limitation to crop improvement using only cultivated germplasm. Transfer of some wild resistance genes to cultivated peanut has been achieved, for instance, the gene for resistance to root-knot nematode. However, a wider use of wild species in breeding has been hampered by ploidy and sexual incompatibility barriers, by linkage drag, and historically, by a lack of the tools needed to conveniently confirm hybrid identities and track introgressed chromosomal segments. In recent years, improved knowledge of species relationships has been gained by more detailed cytogenetic studies and molecular phylogenies. This knowledge, together with new tools for genetic and genomic analysis, will help in the more efficient use of peanut's genetic resources in crop improvement.