Steven B Janssens

Steven B Janssens
Meise Botanic Garden · Research Department

Dr.

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314
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Publications

Publications (314)
Article
Full-text available
Northern Viet Nam displays a remarkable diversity of wild bananas (Musa L.), including the species from which the majority of cultivated bananas derive. The taxonomy and exact distribution of these wild bananas are however not well known, limiting their conservation and use. In the present study, we describe the morphology, ecology, and phytogeogra...
Article
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Background and aims – The genus Impatiens is known for its enormous convergent phenotypic adaptation, with similar floral traits having independently evolved in distantly related lineages. The large functional convergence of Impatiens flowers causes a high degree of homoplasy for several phenotypic characters resulting in increased difficulties to...
Article
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High value commodities such as spices suffer from occasional contaminations of both chemical and biological origin. Consequently, quality control and safety monitoring has become a pressing issue for the spice industry. Two recent independent studies showed that at least one third of the analyzed cumin and green anise spice seeds samples surpassed...
Article
A significant fraction of higher plants in China are threatened due to dramatic landscape transformation and increasing climate change. However, the conservation effectiveness of threatened higher plants (THPs) and their response to climate change are still underexplored to date. Based on the latest list of THPs in China, we obtained 102,593 occurr...
Article
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that accessions could be divided into three main clusters. Vietnamese and Chinese populations were assigned to a first and second cluster respectively. A third cluster consisted of ITC and home garden accessions. Samples from Papua New Guinea were allocated to the cluster with Chinese populations but were assigned to a separate fourth cluster if th...
Article
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Collection and storage of crop wild relative (CWR) germplasm is crucial for preserving species genetic diversity and crop improvement. Nevertheless, much of the genetic variation of CWRs is absent in ex situ collections and detailed passport data are often lacking. Here, we focussed on Musa balbisiana, one of the two main progenitor species of many...
Article
The assessment of population vulnerability under climate change is crucial for planning conservation as well as for ensuring food security. Coffea canephora is, in its native habitat, an understorey tree that is mainly distributed in the lowland rainforests of tropical Africa. Also known as Robusta, its commercial value constitutes a significant re...
Article
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Conventional wisdom states that genetic variation reduces disease levels in plant populations. Nevertheless, crop species have been subject to a gradual loss of genetic variation through selection for specific traits during breeding, thereby increasing their vulnerability to biotic stresses such as pathogens. We explored how genetic variation in Ar...
Article
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Crop wild relatives, the closely related species of crops, may harbor potentially important sources of new allelic diversity for (a)biotic tolerance or resistance. However, to date wild diversity is only poorly characterized and evaluated. Banana has a large wild diversity but only a narrow proportion is currently used in breeding programs. The mai...
Article
Full-text available
Fusarium is one of the most important fungal genera of plant pathogens that affect the cultivation of a wide range of crops. Agricultural losses caused by Fusarium oxysporum f. sp. cubense ( Foc ) directly affect the income, subsistence, and nourishment of thousands of farmers worldwide. For Viet Nam, predictions on the impact of Foc for the future...
Article
Full-text available
Fusarium is one of the most important fungal genera of plant pathogens that affect the cultivation of a wide range of crops. Agricultural losses caused by Fusarium oxysporum f. sp. cubense (Foc) directly affect the income, subsistence, and nourishment of thousands of farmers worldwide. For Viet Nam, predictions on the impact of Foc for the future a...
Article
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[This corrects the article DOI: 10.1093/conphys/coab099.].
Article
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The ability of seeds to withstand drying is fundamental to ex situ seed conservation but drying responses are not well known for most wild species including crop wild relatives. We look at drying responses of seeds of Musa acuminata and Musa balbisiana, the two primary wild relatives of bananas and plantains, using the following four experimental a...
Article
We examined the phylogeny and intrageneric classification of eristaline hoverfly genera from the Afrotropical Region using mitochondrial genomes. Genome skimming was used to obtain (nearly) full mtDNA and nuclear rDNA (18S, 28S) genomes of 120 museum vouchers from eight genera and 98 species. Phylogenetic reconstructions of mitogenomes and mitogeno...
Article
Paganuccia is described as a new genus of Rubiaceae, only known so far from two collections from the continental dunes in the São Francisco River basin, Bahia, north-eastern Brazil. The morphological and molecular phylogenetic analyses based on nuclear (ETS, ITS) and plastid (atpB-rbcL, petD, rps16, trnL-trnF) sequence data, support the recognition...
Article
Coffea rizetiana Stoff. & M.Noirot, sp. nov., a diploid species only known from a single wild population in South-West Cameroon, is formally described here. It is probably extinct in the wild, but is present in the germplasm collection in Bassin Martin (Runion, France) and Meise Botanic Garden (Belgium). Phylogenetic analyses reveal a close relatio...
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Background Comparative phylogeographic studies on rainforest species that are widespread in Central Africa often reveal genetic discontinuities within and between biogeographic regions, indicating (historical) barriers to gene flow, possibly due to repeated and/or long-lasting population fragmentation during glacial periods according to the forest...
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In the species-rich genus Impatiens, few natural hybrids are known, even though closely related species often occur sympatrically. In this study, we aim to bridge the gap between micro- and macro-evolution to disentangle pre- and postzygotic mechanisms that may prevent hybridization in the Impatiens purpureoviolacea complex from Central Africa. We...
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Storing seed collections of crop wild relatives, wild plant taxa genetically related to crops, is an essential component in global food security. Seed banking protects genetic resources from degradation and extinction and provides material for use by breeders. Despite being among the most important crops in the world, banana and plantain crop wild...
Article
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A cryptic invader of the genus Persicaria has recently increased in the damper, northern parts of La Palma and Gran Canaria in the Canary Islands (Spain) and locally behaves as an invasive species. Examination of historical herbarium specimens showed this species to be present in Gran Canaria since the 1960s and the same probably applies to La Palm...
Article
Micrasepalum is a taxonomically and phylogenetically poorly understood genus of Rubiaceae endemic to the global biodiversity hotspot of the Caribbean islands. It has traditionally been associated with species in the Spermacoce clade, but never properly evaluated in a phylogenetic context. Also, little information about seed and fruit morphology of...
Preprint
Full-text available
A cryptic invader of the genus Persicaria is recently increasing in the damper, northern parts of La Palma and Gran Canaria in the Canary Islands (Spain) and locally behaves as an invasive species. Examination of historical herbarium specimens showed this species to be present in Gran Canaria since the 1960’s and the same probably applies to La Pal...
Preprint
Full-text available
Despite their key role in biodiversity conservation, forests of the Congo Basin are increasingly threatened by human activities. Whereas deforestation is very conspicuous, it remains challenging to monitor the impact of forest degradation under a more or less intact canopy. Likewise, the outcomes of forest regeneration following agricultural abando...
Article
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• Ecologically meaningful seed germination experiments are constrained by access to seeds and relevant environments for testing at the same time. This is particularly the case when research is carried out far from the native area of the studied species. • Here, we demonstrate an alternative—the use of glasshouses in botanic gardens as simulated-nat...
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Aim Dispersal and subsequent adaptation to local environmental and climatic conditions play major roles in the evolution and current-day distribution of plants and animals, but their relative importance is not always easy to disentangle. The aim of this study was to provide a comprehensive phylogenetic analysis of the terrestrial orchid genus Cypri...
Article
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Premise: Many cultivated coffee varieties descend from Coffea canephora, commonly known as Robusta coffee. The Congo Basin has a century long history of Robusta coffee cultivation and breeding, and is hypothesized to be the region of origin of many of the cultivated Robusta varieties. Since little is known about the genetic composition of C. canep...
Article
Interspecific hybridization events have played a major role in plant speciation, yet, the evolutionary origin of hybrid species often remains enigmatic. Here, we inferred the evolutionary origin of the allotetraploid species Coffea arabica, which is widely cultivated for Arabica coffee production. We estimated genetic distances between C. arabica a...
Article
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Background Conservation of plant genetic resources, including the wild relatives of crops, plays an important and well recognised role in addressing some of the key challenges faced by humanity and the planet including ending hunger and biodiversity loss. However, the genetic diversity and representativeness of ex situ collections, especially that...
Article
Full-text available
Black nightshade, or the Solanum nigrum complex, includes a number of species that botanists consider problematic due to their morphological resemblance and the high rate of hybridization. As part of the revision of the family Solanaceae for the Flora central Africa,we realized a molecular study of the Solanum nigrum complex in the western part of...
Article
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The Albertine Rift harbours a highly diverse flora with numerous endemic species. An important component of the forest understorey is the herbaceous genus Impatiens. Fieldwork in Burundi, the Democratic Republic of the Congo and Rwanda as well as morphological studies indicated that the Albertine Rift endemic Impatiens purpureoviolacea represents a...
Article
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Insular woodiness (IW), referring to the evolutionary transition from herbaceousness toward woodiness on islands, has arisen more than 30 times on the Canary Islands (Atlantic Ocean). One of the IW hypotheses suggests that drought has been a major driver of wood formation, but we do not know in which palaeoclimatic conditions the insular woody line...
Preprint
Full-text available
Premise: Many cultivated coffee varieties descend from Coffea canephora , commonly known as Robusta coffee. The Congo Basin has a century long history of Robusta coffee cultivation and breeding, and is hypothesized to be the region of origin of many of the cultivated Robusta varieties. Since little is known about the genetic composition of C. canep...
Preprint
Full-text available
Crop wild relatives, the closely related species of crops, may harbor potentially important sources of new allelic diversity for (a)biotic tolerance or resistance. However, to date wild diversity is only poorly characterized and evaluated. Banana has a large wild diversity but only a narrow proportion is currently used in breeding programs. The mai...
Article
Carapa wohllebenii is described as a new tree species from the Democratic Republic of Congo, Rwanda, and Burundi. Its affinities to Carapa grandiflora are discussed. It differs in a number of morphological features; the most prominent being the oblanceolate-oblong leaflets with distinctly mucronate apex and a length/width ratio of 3.2–4.7 (vs. oblo...
Article
Full-text available
Crop wild relatives (CWR) are an indispensable source of alleles to improve desired traits in related crops. While knowledge on the genetic diversity of CWR can facilitate breeding and conservation strategies, it has poorly been assessed. Cultivated bananas are a major part of the diet and income of hundreds of millions of people and can be conside...
Article
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Tropical forests represent vast carbon stocks and continue to be key carbon sinks and buffer climate changes. The international policy constructed several mechanisms aiming at conservation and sustainable use of these forests. Illegal logging is an important threat of forests, especially in the tropics. Several laws and regulations have been set up...
Preprint
Full-text available
Fusarium is one of the most important fungal genera of plant pathogens that affect the cultivation of a wide range of crops. Agricultural losses caused by Fusarium oxysporum f. sp. cubense (Foc) have a direct effect on the income, subsistence and nourishment of thousands of smallholder farmers worldwide. In addition, also commercial growers are str...
Preprint
Full-text available
Background Conservation of plant genetic resources, including the wild relatives of crops, plays an important and well recognised role in addressing some of the key challenges faced by humanity and the planet including ending hunger and biodiversity loss. However, the genetic diversity and representativeness of ex situ collections, especially that...
Article
Full-text available
Many species have been introduced beyond their native ranges and many have become global weeds. Human mediated dispersal has removed the geographic isolation of these species, reversing millions of years of independent evolution. Examples are the Oxalis species in section Corniculatae where several species have become invasive. Here we characterize...
Article
Leaves of the wild yam species Dioscorea sansibarensis display prominent forerunner or "drip" tips filled with extracellular bacteria of the species Orrella dioscoreae.1 This species of yam is native to Madagascar and tropical Africa and reproduces mainly asexually through aerial bulbils and underground tubers, which also contain a small population...
Article
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Aim Crop wild relatives (CWR) are an essential source of genetic material for the improvement of certain traits in related crop species. Despite their importance, increasing public, scientific and political support, large gaps exist in the amount of genetic material collected and conserved of many CWR. Here, we construct a dataset on the distributi...
Article
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Background: The current data paper aims to interlink the African plant collections of the Meise Botanic Garden Herbarium (BR) and the Royal Museum for Central Africa Xylarium (Tw). Complementing both collections strengthens the reference value of each institutional collection, as more complete metadata are made available and it enables increased q...
Article
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Background-This contribution is part of an ongoing study on the taxonomy and the phylogenetic relationships of the Malagasy representatives of the tribe Pavetteae (Rubiaceae). Material and methods-Taxonomic methods follow normal practice of herbarium taxonomy. A molecular study using the plastid markers rps16, trnT-F, petD, and accD-psa1, the nucle...
Article
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Seed conservation of banana crop wild relatives (Musa L. spp.) is limited because of lack of knowledge about their germination ecology. Musa acuminata Colla, the most important banana crop wild relative, is distributed in tropical and subtropical Asian and Pacific rainforests and colonizes disturbed sites. The role of temperature in stimulating/inh...
Article
The species-rich flora of Madagascar is well known for a range of unusual floral ecologies. One example is Impatiens section Trimorphopetalum with its unique combination of floral traits: small, spur-less, cup- or lip-shaped, greenish or brownish flowers. So far no hypotheses on floral function or pollination of this peculiar group have been propos...
Chapter
Bananas and plantains (Musa spp.) are amongst the most important tropical and subtropical food crops in the world. In order to reduce the impact of biotic and abiotic factors on banana cultivation, it is important to allow for a genetic enrichment of the currently cultivated genepool. Crop Wild Relatives play an important role in modern plant breed...
Article
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Based on morphological characteristics, genome size and molecular phylogenetics the identity of introduced taxa of Artemisia section Artemisia in Belgium and the Netherlands was critically reassessed. It was shown that several populations of alleged A. verlotiorum belong to A. princeps instead. This species is native to Eastern Asia (China, Japan a...
Article
Background and Aims Floral diversity as a result of plant-pollinator interactions can evolve by two distinct processes: shifts between pollination systems, or divergent use of the same pollinator. Although both pollinator-driven, the mode, relative importance, and inter-dependence of these different processes are rarely studied simultaneously. Here...
Article
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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, add...
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Aim The Guineo‐Congolian region in Africa constitutes the second largest area of tropical rainforest (TRF) in the world. It covered an estimated 15–22 million km² during the late Miocene (55–11 Ma) and it has experienced since a declining trend, currently reaching 3.4 million km², associated with increasing aridification and the replacement of TRF...
Article
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Ex situ seed conservation of banana crop wild relatives (Musa spp. L.), is constrained by critical knowledge gaps in their storage and germination behaviour. Additionally, challenges in collecting seeds from wild populations impact the quality of seed collections. It is, therefore, crucial to evaluate the viability of seeds from such collecting mis...
Article
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Tropical Africa is home to an astonishing biodiversity occurring in a variety of ecosystems. Past climatic change and geological events have impacted the evolution and diversification of this biodiversity. During the last two decades, around 90 dated molecular phylogenies of different clades across animals and plants have been published leading to...
Article
Temporal and spatial patterns in flowering phenology were assessed for eight tropical African tree species. Specifically, the frequency and seasonality of flowering at seven sites in central Africa were determined using field data, graphical analysis and circular statistics. Additionally, spatial variation in the timing of flowering across species...
Article
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Since natural habitats are disappearing fast, there is an urgent need to collect, characterize and phenotype banana crop wild relatives to identify unique genotypes with specific traits that fill the gaps in our gene banks. We report a collection mission in Papua New Guinea carried out in 2019. Seed containing bunches were collected from Musa peeke...
Article
For decades coffees were associated with the genus Coffea. In 2011, the closely related genus Psilanthus was subsumed into Coffea. However, results obtained in 2017—based on 28,800 nuclear SNPs—indicated that there is not substantial phylogenetic support for this incorporation. In addition, a recent study of 16 plastid full-genome sequences highlig...
Article
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Soil micro-organisms drive the global carbon and nutrient cycles that underlie essential ecosystem functions. Yet, we are only beginning to grasp the drivers of terrestrial microbial diversity and biogeography, which presents a substantial barrier to understanding community dynamics and ecosystem functioning. This is especially true for soil protis...
Preprint
Full-text available
Aim: Insular woodiness, referring to the evolutionary transition from herbaceousness towards woodiness on islands, has arisen at least 38 times on the Canary Islands. Distribution patterns and physiological experiments have suggested a link between insular woodiness and increased drought stress resistance in current-day species, but we do not know...
Article
Full-text available
In Rubiaceae phylogenetics, the number of markers often proved a limitation with authors failing to provide well-supported trees at tribal and generic levels. A robust phylogeny is a prerequisite to study the evolutionary patterns of traits at different taxonomic levels. Advances in next-generation sequencing technologies have revolutionized biolog...
Preprint
Full-text available
Interspecific hybridization events have played a major role in plant speciation, yet, the evolutionary origin of hybrid species often remains enigmatic. Here, we inferred the evolutionary origin of the allotetraploid species Coffea arabica , which is widely cultivated for Arabica coffee production. We estimated genetic distances between C. arabica...
Article
1.Climate change will increase the level of drought stress experienced by plant communities, but the spatial distribution of projected changes in dryness remains highly uncertain. Species can, to some extent, deal with climate uncertainty through natural variation in adaptive responses to environmental heterogeneity and predictability. Biodiversity...