Mimosoid Legumes Research Articles

The invasive mimosoid legume Dichrostachys cinerea (L.) Wight & Arn is nodulated by diverse strains of Ensifer and Bradyrhizobium in different agroclimatic regions of India

The invasive mimosoid legume Dichrostachys cinerea (L.) Wight & Arn is nodulated by diverse strains of Ensifer and Bradyrhizobium in different agroclimatic regions of India

Basal bud banks are the primary determinants of survival in woody legume seedlings after clipping

Disturbances determine the structure of savannas by influencing growth at all stages of a tree's life. Since the seedling stage is such a significant part of a tree's life cycle, greater knowledge of this stage informs woody management and encroachment prevention. In this study, we tested the effect of a suite of seedling functional traits on seedling survival after experimentally-induced disturbance. Twelve mimosoid legume tree species, an important group in African savannas, with different provenances, were grown from seed under experimental conditions. Seedlings were clipped at 1 cm above ground at age 30 days, to simulate disturbance, and their survival recorded. A number of above- and below-ground traits quantifying height, biomass, bud bank and architecture were measured prior to clipping in order to assess what traits could be responsible for post-clipping survival. We also quantified root contraction by calculating the change in height of the lowest bud between the ages of 6 and 60 days. Fire regime and browser biomass of the native range of each species were calculated to test whether these factors predicted seedling survival. Seedling survival was primarily predicted by the whether the plant possessed a bud below 1 cm above ground level, i.e. below the height of clipping. For the first time we report that, in several Vachellia species, root contraction occurred, bringing basal buds closer to the ground, and in some cases below the ground, thus increasing seedling survival after clipping. No environmental variables were significant predictors of survival. Our results suggest that, at this young age, buds close to the soil surface are the most important trait predicting seedling survival, while other traits that are important for saplings and adults do not significantly influence the survival of seedlings. At the seedling stage, herbivory and fire are possibly inflicting the same degree of selection pressures and thus little trait differentiation is evident across the environmental gradient.

Comparative phylotranscriptomics reveals ancestral and derived root nodule symbiosis programmes

Symbiotic interactions such as the nitrogen-fixing root nodule symbiosis (RNS) have structured ecosystems during the evolution of life. Here we aimed at reconstructing ancestral and intermediate steps that shaped RNS observed in extant flowering plants. We compared the symbiotic transcriptomic responses of nine host plants, including the mimosoid legume Mimosa pudica for which we assembled a chromosome-level genome. We reconstructed the ancestral RNS transcriptome composed of most known symbiotic genes together with hundreds of novel candidates. Cross-referencing with transcriptomic data in response to experimentally evolved bacterial strains with gradual symbiotic proficiencies, we found the response to bacterial signals, nodule infection, nodule organogenesis and nitrogen fixation to be ancestral. By contrast, the release of symbiosomes was associated with recently evolved genes encoding small proteins in each lineage. We demonstrate that the symbiotic response was mostly in place in the most recent common ancestor of the RNS-forming species more than 90 million years ago.

Sympetaly in the mimosoid clade (Leguminosae, Caesalpinioideae): An unusual trait in the rosid group

Sympetaly is a notable feature within the mimosoid clade (Leguminosae: Caesalpinioideae), specially as it is uncommon in rosids. The way the petals are organized, forming a tubular corolla by the union of the petals directly affects the perception of pollinators. This study examines whether the petal union leading to a sympetalous corolla in the mimosoid clade is widespread and whether there is variation in type and extent. For this purpose, floral buds and flowers of 16 species from 13 genera were collected, fixed, and processed for analysis by light and scanning electron microscopy. Most species studied display a pentamerous sympetalous corolla with free lobes. The petal primordia are individualized and emerge simultaneously on the floral apex, alternating with the sepal primordia. Petals remain free at the beginning of the intermediate stages of development, and subsequently, the petals curve and approach each other, and their margins touch. Epidermal papillae are found on the petals’ apical margin interconnecting the lobes, which enclose the inner organs of the floral bud. The structure of the sympetalous corolla is variable regarding the type and extent of the union. Four different types of sympetaly were found and classified as follows: 1. full connation - petals fully united along their length; 2. connation-coherence - petals genuinely united in the basal portion and coherent in the median and apical portion; 3. full coherence - petals intertwined with papillae throughout; and 4. partial coherence - free petals at the base and intertwined with papillae in the middle and apical portion. Thus, sympetaly of mimosoid legumes results from postgenital union of the petals at the apical, median, and basal regions during their development by tissue union (connation), intertwining of epidermal papillae (coherence), or both processes. The mucilage cells found along the petals guarantee the stabilization and flexibility of the tubes, in addition to contributing to the protection of the internal organs of the flower. Although more studies on floral development are needed to understand the evolution of this unusual trait, connation appears to be a derived trait within mimosoids.

Precipitation is the main axis of tropical plant phylogenetic turnover across space and time.

Early natural historians-Comte de Buffon, von Humboldt, and De Candolle-established environment and geography as two principal axes determining the distribution of groups of organisms, laying the foundations for biogeography over the subsequent 200 years, yet the relative importance of these two axes remains unresolved. Leveraging phylogenomic and global species distribution data for Mimosoid legumes, a pantropical plant clade of c.3500 species, we show that the water availability gradient from deserts to rain forests dictates turnover of lineages within continents across the tropics. We demonstrate that 95% of speciation occurs within a precipitation niche, showing profound phylogenetic niche conservatism, and that lineage turnover boundaries coincide with isohyets of precipitation. We reveal similar patterns on different continents, implying that evolution and dispersal follow universal processes.

Misleading fruits: The non-monophyly of Pseudopiptadenia and Pityrocarpa supports generic re-circumscriptions and a new genus within mimosoid legumes.

Generic delimitation in Piptadenia and allies (mimosoid legumes) has been in a state of flux, particularly caused by over-reliance on fruit and seed morphology to segregate species out of Piptadenia into the genera Parapiptadenia, Pityrocarpa and Pseudopiptadenia. Although supporting their segregation from Piptadenia, previous phylogenetic analyses suggested that some of these segregated genera are not monophyletic. Here, we test the monophyly of Parapiptadenia, Pityrocarpa and Pseudopiptadenia with dense taxon sampling across these genera, including the type species of each genus. Our analysis recovers Parapitadenia as monophyletic, but places Pseudopiptadenia species in two distinct lineages, one of which includes all three species of Pityrocarpa. Given that the type species of both Pseudopiptadenia and Pityrocarpa are nested in the same clade, we subsume Pseudopiptadenia under the older name Pityrocarpa. The remaining Pseudopiptadenia species are assigned to the new genus Marlimorimia. Alongside high molecular phylogenetic support, recognition of Parapiptadenia, Pityrocarpa and Marlimorimia as distinct genera is also supported by combinations of morphological traits, several of which were previously overlooked.

Phylogeny and classification of the Australasian and Indomalayan mimosoid legumes Archidendron and Archidendropsis (Leguminosae, subfamily Caesalpinioideae, mimosoid clade).

The morphologically variable genus Archidendron is the second largest mimosoid legume genus from the Indomalayan-Australasian region, yet it has not been well represented in phylogenetic studies. Phylogenies that have included multiple representatives of Archidendron suggest it may not be monophyletic, and the same applies to Archidendropsis, another understudied genus of the Archidendron clade. The most comprehensive phylogeny of Archidendron and Archidendropsis to date is presented, based on four nuclear markers (ITS, ETS, SHMT and RBPCO). Exemplars from all genera of the wider Archidendron clade are sampled, including representatives of all series within Archidendron and the two subgenera of Archidendropsis. Our results confirm that Archidendron and Archidendropsis are not monophyletic. Within Archidendron, only one series (ser. Ptenopae) is resolved as monophyletic and species of Archidendron are divided into two primarily geographic lineages. One clade is distributed in western Malesia and mainland Asia and includes most representatives of series Clypeariae, while the other is mostly restricted to eastern Malesia and Australia and includes representatives of the seven other series plus two samples of series Clypeariae. No taxonomic changes are made for Archidendron due to the high level of topological uncertainty and the lack of discrete macromorphological characters separating these two lineages. Each of the two subgenera of Archidendropsis is monophyletic but they are not closely related. A new genus endemic to Queensland (Australia), Heliodendron Gill.K. Br. & Bayly, gen. nov., is described for the former Archidendropsissubg.Basaltica, and combinations for its three species are proposed: Heliodendronbasalticum (F. Muell.) Gill.K. Br. & Bayly, comb. nov., Heliodendronthozetianum (F. Muell.) Gill.K. Br. & Bayly, comb. nov., and Heliodendronxanthoxylon (C.T. White & W.D. Francis) Gill.K. Br. & Bayly, comb. nov.

Mezcala - a new segregate genus of mimosoid legume (Leguminosae, Caesalpinioideae, mimosoid clade) narrowly endemic to the Balsas Depression in Mexico.

Recent results have demonstrated that the genus Desmanthus is non-monophyletic because the genus Kanaloa is nested within it, with a single species, Desmanthusbalsensis placed as sister to the clade comprising Kanaloa plus the remaining species of Desmanthus. Here we transfer D.balsensis to a new segregate genus Mezcala, discuss the morphological features supporting this new genus, present a key to distinguish Mezcala from closely related genera in the Leucaena subclade, and provide a distribution map of M.balsensis.

Boliviadendron, a new segregate genus of mimosoid legume (Leguminosae, Caesalpinioideae, mimosoid clade) narrowly endemic to the interior Andean valleys of Bolivia.

Phylogenetic analyses of DNA sequence data sampling all species of Leucochloron alongside representatives of genera of the Inga and Albizia clades of the larger ingoid clade of mimosoid legumes (sensu Koenen et al. 2020) confirm the non-monophyly of the genus Leucochloron. We show that Leucochloronbolivianum is placed in the Albizia clade, while the remaining four species of Leucochloron are placed in the Inga clade, in line with previous results. To rectify this non-monophyly, L.bolivianum is segregated as the new genus, Boliviadendron, with a single species, Boliviadendronbolivianum, narrowly endemic to the interior Andean valleys of Bolivia. We illustrate this new segregate genus, present a map of its distribution and discuss the striking lack of morphological distinctions between Boliviadendron and Leucochloron, as well as the phylogenetic and morphological affinities of Boliviadendron to the genera Enterolobium and Albizia.

Osodendron gen. nov. (Leguminosae, Caesalpinioideae), a new genus of mimosoid legumes of tropical Africa.

The genus Osodendron is here newly described to accommodate three species and one subspecies of African mimosoid legumes. These taxa have previously been included by several authors in Albizia, Cathormion and/or Samanea, but they have been shown to be phylogenetically unrelated to any of these, being instead the sister-group of the recently described Neotropical genus Robrichia, which is similar in vegetative morphology and especially its very similar indumentum, but is decidedly different in pod morphology. A taxonomic treatment of the three species in the genus is presented, with species descriptions, photographs, distribution maps and an identification key. The type species Osodendronaltissimum (Hook. f.) E.J.M. Koenen occurs in swamp and riverine rainforest and gallery forests, with the typical subsp. altissimum widespread across tropical Africa, while Osodendronaltissimumsubsp.busiraensis (G.C.C. Gilbert) E.J.M. Koenen is only known from the Busira river catchment in the western part of the Democratic Republic of Congo. Of the other two species, Osodendrondinklagei (Harms) E.J.M. Koenen is a common tree of rainforest and the forest-savannah transition including semi-deciduous and secondary forest as well as gallery forest and is restricted to Upper Guinea and the similar, but vegetatively more variable Osodendronleptophyllum (Harms) E.J.M. Koenen occupies comparable vegetation types in Lower Guinea and extends marginally into the Sudanian and Zambezian savannahs in gallery forest.

The Genome of the Mimosoid Legume Prosopis cineraria, a Desert Tree.

The mimosoid legumes are a clade of ~40 genera in the Caesalpinioideae subfamily of the Fabaceae that grow in tropical and subtropical regions. Unlike the better studied Papilionoideae, there are few genomic resources within this legume group. The tree Prosopis cineraria is native to the Near East and Indian subcontinent, where it thrives in very hot desert environments. To develop a tool to better understand desert plant adaptation mechanisms, we sequenced the P. cineraria genome to near-chromosomal assembly, with a total sequence length of ~691 Mb. We predicted 77,579 gene models (76,554 CDS, 361 rRNAs and 664 tRNAs) from the assembled genome, among them 55,325 (~72%) protein-coding genes that were functionally annotated. This genome was found to consist of over 58% repeat sequences, primarily long terminal repeats (LTR-)-retrotransposons. We find an expansion of terpenoid metabolism genes in P. cineraria and its relative Prosopis alba, but not in other legumes. We also observed an amplification of NBS-LRR disease-resistance genes correlated with LTR-associated retrotransposition, and identified 410 retrogenes with an active burst of chimeric retrogene creation that approximately occurred at the same time of divergence of P. cineraria from a common lineage with P. alba~23 Mya. These retrogenes include many biotic defense responses and abiotic stress stimulus responses, as well as the early Nodulin 93 gene. Nodulin 93 gene amplification is consistent with an adaptive response of the species to the low nitrogen in arid desert soil. Consistent with these results, our differentially expressed genes show a tissue specific expression of isoprenoid pathways in shoots, but not in roots, as well as important genes involved in abiotic salt stress in both tissues. Overall, the genome sequence of P. cineraria enriches our understanding of the genomic mechanisms of its disease resistance and abiotic stress tolerance. Thus, it is a very important step in crop and legume improvement.

Genomics and transcriptomics insights into luteolin effects on the beta-rhizobial strain Cupriavidus necator UYPR2.512.

Cupriavidus necator UYPR2.512 is a rhizobial strain that belongs to the Beta-subclass of proteobacteria, able to establish successful symbiosis with Mimosoid legumes. The initial steps of rhizobium-legumes symbioses involve the reciprocal recognition by chemical signals, being luteolin one of the molecules involved. However, there is a lack of information on the effect of luteolin in beta-rhizobia. In this work, we used long-read sequencing to complete the genome of UYPR2.512 providing evidence for the existence of four closed circular replicons. We used an RNA-Seq approach to analyse the response of UYPR2.512 to luteolin. One hundred and forty-five genes were differentially expressed, with similar numbers of downregulated and upregulated genes. Most repressed genes were mapped to the main chromosome, while the upregulated genes were overrepresented among pCne512e, containing the symbiotic genes. Induced genes included the nod operon and genes implicated in exopolysaccharides and flagellar biosynthesis. We identified many genes involved in iron, copper and other heavy metals metabolism. Among repressed genes, we identified genes involved in basal carbon and nitrogen metabolism. Our results suggest that in response to luteolin, C. necator strain UYPR2.512 reshapes its metabolism in order to be prepared for the forthcoming symbiotic interaction.

Reinstatement and recircumscription ofJupunbaandPunjuba(Fabaceae) based on phylogenetic evidence

AbstractAmong the mimosoid legumes (Fabaceae, Caesalpinioideae, mimosoid clade), many genera have complex nomenclatural histories, including Abarema that stands out due to numerous nomenclatural changes. Abarema is a Neotropical genus that currently comprises c. 50 species, with centres of diversity in the Amazon and Atlantic rain forests. Recent phylogenetic studies of Abarema have demonstrated the non-monophyly of the genus, which was shown to be polyphyletic with species traditionally recognized under the genus placed in three main clades that are intermingled with other genera of the former tribe Ingeae. The type species of Abarema groups with Inga, Macrosamanea, Enterolobiump.p., Zygia and Blanchetiodendron, whereas the other two clades correspond to the former genera Jupunba and Punjuba. The aim of this study is to build a phylogenetic tree of Abarema s.l. supporting the reinstatement of Jupunba and Punjuba, based on morphological and phylogenetic evidence, and to carry out a nomenclatural overhaul of the species and implement necessary typifications. For Punjuba we reinstate three species and add three new combinations. Jupunba comprises 37 species, of which eight are reinstated; in addition, the resurrection of one species with a new synonym is proposed and 29 new combinations are made. In total, 63 taxa are revised, including accepted names, synonyms and excluded names. A taxonomic key is presented for the identification of Punjuba, Jupunba and related genera. We present 40 new combinations, one new taxonomic status and 18 corrections of nomenclature category for lectotypes and two neotypes. One lectotype is designated, one species is reinstated with a new synonym and a second step neotypification is made. We located 97 unreported types during the revision, which are cited here for the first time.

Queiroziella gen. nov., a new genus of jumping plant-lice (Hemiptera, Psyllidae) from Southern Brazil associated with Mimosa scabrella (Leguminosae).

Queiroziella gen. nov., a new genus of Psylloidea (Psyllidae, Ciriacreminae), is erected for five new species developing on the multipurpose tree Mimosa scabrella (Leguminosae, Caesalpinioideae, mimosoid clade): viz. Queiroziella erato sp. nov., Q. euterpe sp. nov., Q. melpomone sp. nov., Q. terpsichore sp. nov. and Q. thalia sp. nov. Another species from Paraguay, associated with an unidentified Mimosa species, is transferred to the new genus as Queiroziella borealis (Burckhardt, 1987), comb. nov., from Zonopelma (Aphalaroidinae). The new taxa are diagnosed, described and illustrated, and keys are provided for the identification of adults and immatures. Morphologically, Queiroziella resembles Heteropsylla which is also associated with mimosoid legumes and with which it may be closely related. As their host, the new species are restricted to Southern Brazil. Queiroziella euterpe, Q. melpomone and Q. terpsichore are reported from the states of Paraná, Rio Grande do Sul, Santa Catarina and São Paulo, Q. thalia from Paraná and São Paulo, and Q. erato from Paraná. No clear phenological patterns were found though it seems that high psyllid populations coincide with new flush of the host plants. Despite that the psyllids occur sometimes in very high numbers, no visible damage could be detected on host trees. On the other hand, the honeydew of the psyllids may provide a food source for honey-bees during non-flowering periods of Mimosa scabrella.

Hybrid capture of 964 nuclear genes resolves evolutionary relationships in the mimosoid legumes and reveals the polytomous origins of a large pantropical radiation.

PREMISETargeted enrichment methods facilitate sequencing of hundreds of nuclear loci to enhance phylogenetic resolution and elucidate why some parts of the “tree of life” are difficult (if not impossible) to resolve. The mimosoid legumes are a prominent pantropical clade of ~3300 species of woody angiosperms for which previous phylogenies have shown extensive lack of resolution, especially among the species‐rich and taxonomically challenging ingoids.METHODSWe generated transcriptomes to select low‐copy nuclear genes, enrich these via hybrid capture for representative species of most mimosoid genera, and analyze the resulting data using de novo assembly and various phylogenomic tools for species tree inference. We also evaluate gene tree support and conflict for key internodes and use phylogenetic network analysis to investigate phylogenetic signal across the ingoids.RESULTSOur selection of 964 nuclear genes greatly improves phylogenetic resolution across the mimosoid phylogeny and shows that the ingoid clade can be resolved into several well‐supported clades. However, nearly all loci show lack of phylogenetic signal for some of the deeper internodes within the ingoids.CONCLUSIONSLack of resolution in the ingoid clade is most likely the result of hyperfast diversification, potentially causing a hard polytomy of six or seven lineages. The gene set for targeted sequencing presented here offers great potential to further enhance the phylogeny of mimosoids and the wider Caesalpinioideae with denser taxon sampling, to provide a framework for taxonomic reclassification, and to study the ingoid radiation.

Paraburkholderia youngii sp. nov. and ‘Paraburkholderia atlantica’ – Brazilian and Mexican Mimosa-associated rhizobia that were previously known as Paraburkholderia tuberum sv. mimosae

Previous studies have recognized South and Central/Latin American mimosoid legumes in the genera Mimosa, Piptadenia and Calliandra as hosts for various nodulating Paraburkholderia species. Several of these species have been validly named in the last two decades, e.g., P. nodosa, P. phymatum, P. diazotrophica, P. piptadeniae, P. ribeironis, P. sabiae and P. mimosarum. There are still, however, a number of diverse Paraburkholderia strains associated with these legumes that have an unclear taxonomic status. In this study, we focus on 30 of these strains which originate from the root nodules of Brazilian and Mexican Mimosa species. They were initially identified as P. tuberum and subsequently placed into a symbiovar (sv. mimosae) based on their host preferences. A polyphasic approach for the delineation of these strains was used, consisting of genealogical concordance analysis (using atpD, gyrB, acnA, pab and 16S rRNA gene sequences), together with comparisons of Average Nucleotide Identity (ANI), DNA G+C content ratios and phenotypic characteristics with those of the type strains of validly named Paraburkholderia species. Accordingly, these 30 strains were delineated into two distinct groups, of which one is conspecific with ‘P. atlantica’ CNPSo 3155T and the other new to Science. We propose the name Paraburkholderia youngii sp. nov. with type strain JPY169T (= LMG 31411T; SARCC751T) for this novel species.

Species delimitation and phylogeography of African tree populations of the genus Parkia (Fabaceae)

In the pantropical mimosoid legume genus Parkia, taxonomic classification has remained controversial in Africa due to clinal phenotypic variations. Three species (P. biglobosa, P. bicolor, and P. filicoidea) are currently recognized, ranging from West to East Africa, with partially overlapping ranges across different floristic regions. However, additional taxa (species or varieties) have been suggested by different authors. To assess species boundaries of African Parkia and phylogeographic patterns within species, we genotyped 889 individuals using 10 microsatellite markers and compared our results with existing morphological descriptions. Bayesian genetic clustering confirmed the species boundaries assessed from morphological traits and did not reveal introgression but identified genetic discontinuities within each species. Six moderately differentiated genetic clusters were recovered in P. biglobosa (pairwise FST: 0.05–0.19), while P. bicolor and P. filicoidea, each, displayed four well-differentiated clusters (FST: 0.18–0.41 and 0.11–0.34, respectively). Within each species, genetic clusters occurred in parapatry. Parkia biglobosa clusters were congruent with the longitudinal clinal variation in leaflets sizes but 26% of individuals presented admixed genotypes. Genetic clusters in P. bicolor and P. filicoidea followed environmental gradients as well as phytogeographic subdivisions. They were also largely congruent with morphological discontinuities described in previous taxonomic studies and < 10% individuals showed admixed genotypes. We conclude that only one species (P. biglobosa) should be considered in the Guineo-Sudanian savanna. However, P. bicolor and P. filicoidea might each represent a complex of (sub)species. Thus, the hypotheses of cryptic species within P. bicolor and P. filicoidea should be further investigated by testing reproductive barriers.

Emergence of β-rhizobia as new root nodulating bacteria in legumes and current status of the legume–rhizobium host specificity dogma

Recent developments in the legume rhizobium symbiotic interaction particularly those related to the emergence of novel strains of bacteria that nodulate and fix nitrogen in legumes is gaining momentum. These novel strains of bacteria were mostly isolated from the root nodules of indigenous and invasive legumes belonging to the sub families Papilionoideae and Mimosoideae in South Africa, South America and South East China. These rhizobia are phylogenetically and taxonomically different from the traditional 'alpha rhizobia' and are termed 'β-rhizobia' as they belong to the β-sub class of Proteobacteria. There are also new reports of novel species of root nodulating bacteria from the α-Proteobacteria, not known for several decades since the discovery of rhizobia. However, in this review focus is given to the emerging β-rhizobia isolated from the indigenous Papilionoid legumes in the Cape Floristic regions in South Africa and the indigenous and invasive Mimosoid legumes in South America and South East Asia respectively. The nodulation of the indigenous South African Papilionoid legumes including that of Aspalathus linearis (rooibos) is discussed in a bit detail. Previous reports indicated that A. linearis is very specific in its rhizobium requirement and was reported to be nodulated by the slow growing Bradyrhizobium spp. This review however summarizes that the bacteria associated with the root nodules of A. linearis belong to members of both the alpha (α) Proteobacteria that include Mesorhizobium, Rhizobium and Bradyrhizobium spp. and the beta (β) Proteobacteria represented by the genus Burkholderia (now reclassified as Paraburkholderia). In addition, the occurrence of Paraburkholderia as the newly emerging root nodule symbionts of various other legumes has been discussed. In doing so, the review highlights that nodulation is no longer restricted to the traditional 'rhizobia' group following the emergence of the new beta rhizobia as potential nodulators of various indigenous legumes. It thus provides some insights on the status of the legume-rhizobium host specificity concept and the loss of this specificity in several symbiotic associations that puts the long held dogma of host specificity of the legume rhizobium symbiosis in a dilemma.

The Mimosoid tree Leucaena leucocephala can be nodulated by the symbiovar genistearum of Bradyrhizobium canariense

Leucaena leucocephala is a Mimosoid legume tree indigenous to America that has spread to other continents, although it is not still present in some European countries such as Portugal. Nevertheless, we found that this legume can be nodulated in this country by slow-growing rhizobial strains which were identified as Bradyrhizobium canariense trough the analysis of the core genes recA and glnII. The analysis of the symbiotic gene nodC showed that these strains belong to the symbiovar genistearum, which commonly nodulates Genistoid legumes. Although two strains nodulating L. leucocephala in China and Brazil were classified within the genus Bradyrhizobium, they belong to undescribed species and to the symbiovars glycinearum and tropici, respectively. Therefore, we report here for the first time the ability of L. leucocephala to establish symbiosis with strains of B. canariense sv genistearum confirming the high promiscuity of L. leucocephala, that allows it to establish symbiosis with rhizobia native to different continents increasing its invasiveness potential.

Phylogeny of the Neotropical legume genera Zygia and Marmaroxylon and close relatives

AbstractThe Neotropical legume genera Zygia and Marmaroxylon have traditionally been considered closely related and are sometimes treated as congeners. They have been referred to the mimosoid tribe Ingeae based on their possession of flowers with basally fused stamen filaments. However, their systematic status and position have not been analysed in a phylogenetic context. This study provides the first molecular phylogeny of Zygia and Marmaroxylon and closely related mimosoid legume genera, particularly from the tribe Ingeae. DNA sequence data were derived from the nuclear external transcribed spacer (ETS) and the internal transcribed spacer (ITS), and from the chloroplast psbA‐trnH and trnL‐trnF regions, and were analysed using Bayesian inference. In all, 29 species of Zygia and 7 species of Marmaroxylon were included in the study along with representative species from the closely related genera Abarema, Acacia s.str., Archidendropsis, Calliandra, Chloroleucon, Cojoba, Faidherbia, Havardia, Hydrochorea, Inga, Leucochloron, Macrosamanea, Pithecellobium, Pseudosamanea, Samanea, Senegalia, Vachellia and Zapoteca. The results show that neither Zygia nor Marmaroxylon are monophyletic as presently circumscribed. Furthermore, these two genera are not monophyletic together. None of the nine presently recognized sections of Zygia that contain more than one species are shown to be monophyletic. Two of the monospecific sections of Zygia, sect. Ingopsis (Z. inundata) and sect. Pseudocojoba (Z. sabatieri), were found in a clade together with species of Inga. Marmaroxylon ocumarense and M. magdalenae, previously treated as synonyms (as Zygia), are not conspecific, and are found in a clade with Macrosamanea and in a clade with species of Abarema and Hydrochorea, respectively. Our results also show the Inga alliance to be non‐monophyletic. In correspondence with the results presented, all species referred to Marmaroxylon, except for M. ocumarense and M. magdalenae, are here included in Zygia, and Z. inundata is treated in Inga, in which genus it was first described.