plant sciences

Major advances in our understanding of New World Morning Glories

John Wood of the Oxford team members collecting plants in Bolivia
Photo by BRM Williams

A major advance in revealing the unknown plant diversity on planet Earth is made with a new monograph, published in the open-access, peer-reviewed journal PhytoKeys. The global-wide study, conducted by researchers at the University of Oxford, lists details about each of the 425 New World species in the largest genus within the family of morning glories, thanks to an all-round approach combining standard, modern and new-generation identification techniques.

The family of morning glories, also known as bindweeds, whose scientific name is Convolvulaceae, includes prominent members like the sweet potato and ornamental plants such as the moonflower and the blue dawn flower. In fact, one of the key conclusions, made in the present work, is that within this plant group there are many other species, besides the sweet potato, that evolved storage roots long before modern humans appeared on Earth. Furthermore, most of those are yet to be evaluated for economic purposes.

Sweet potato (*Ipomoea batatas*) growing as a weed in a waste ground, San Ramon, Peru
Photo by Robert Scotland

To make their findings, the research team of John Wood, Dr Pablo Muñoz Rodríguez, Bethany R.M. Williams and Prof Robert Scotland applied the “foundation monograph” concept that they had developed for similarly diverse and globally distributed, yet largely understudied groups. Usually, such groups with hundreds of species have never been surveyed across their entire geographical range, which in turn results in the existence of many overlooked new species or species wrongly named.

As a result, the monograph adds six new to science species and establishes nine new subspecies, previously recognised as either distinct species or varieties. The publication also cites all countries where any of those 425 morning glories occurs. In order to provide detailed knowledge about their identities and ecologies, the authors also produced over 200 illustrative figures: both line drawings and photos.

In their study, the scientists also investigate poorly known phenomena concerning the genus. For instance, the majority of the plants appear to originate from two very large centres, from where they must have consequently radiated: the Parana region of South America and the Caribbean Islands. Today, however, a considerable amount of those species can be found all around the globe. Interestingly, the team also notes a strong trend for individual species or clades (separate species with a common ancestor) to inhabit disjunct localities at comparable latitudes on either side of the tropics in North America and South America, but not the Equator.

**Prof Robert Scotland (University of Oxford) with the evolutionary tree of *Ipomoea* that includes 2000 specimens sequenced for DNA**
**Photo by John Baker**

The monograph exemplifies the immense value of natural history collections. Even though the researchers have conducted fieldwork, most of their research is based on herbarium specimens. They have even managed to apply DNA sequencing to specimens over 100 years old. The publication also provides detailed information about the characteristics, distribution and ecology of all the species. It is illustrated with over 200 figures, both line drawings and photos.

“A major challenge in monographing these groups is the size of the task given the number of species, their global distribution and extensive synonymy, the large and increasing number of specimens, the numerous and dispersed herbaria where specimens are housed and an extensive, scattered and often obscure literature,”
comment the scientists.

“Unlike traditional taxonomic approaches, the ‘foundation monograph’ relies on a combination of standard techniques with the use of online digital images and molecular sequence data. Thereby, the scientists are able to focus on species-level taxonomic problems across the entire distribution range of individual species,”
they explained.

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In a separate paper, published in Nature Plants last November, the research team provides further insights into how they have assembled the monograph and include all the molecular sequence data and phylogenetics produced during their work.

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Original source:
Wood JR.I, Muñoz-Rodríguez P, Williams BR.M, Scotland RW (2020) A foundation monograph of Ipomoea (Convolvulaceae) in the New World. PhytoKeys 143: 1-823. https://doi.org/10.3897/phytokeys.143.32821

Survival of soil organisms is a wake-up call for biosecurity

Tiny creatures in soil that attack plants have shown the ability to survive for at least three years stored in dry conditions in a recent AgResearch study, giving new insights into the biosecurity threats posed by passenger travel and trade between countries. The research article is published in the open access journal Neobiota.

The findings of the study also add to the discussions about how best to detect these creatures, called nematodes, before they cross borders and potentially reduce yields of important crops and pasture.

Nematodes are very small worm-like organisms. They can be extremely hardy and can have both beneficial and detrimental impacts. The harmful ones, the plant parasitic nematodes (PPN) include species that attack plants reducing their growth and survival.

In the study, funded by AgResearch via the Better Border Biosecurity collaboration, soil collected from a native forest and an organic orchard was stored separately in cupboards at room temperature for a period of 36 months.

Samples were then taken at regular intervals to see if any nematodes could be recovered from the soil and, if they could, whether they were able to infect plant hosts.

“In the study we used different methods to detect nematodes — including a water misting technique to draw them out of the soil, and a baiting method — where we grew white clover and ryegrass plants in pots containing a soil sample,” explain the authors.

“One of the PPN we looked at was the root lesion nematode. What we found was that lesion nematodes were able to successfully invade the roots of ryegrass even after 36 months,” says AgResearch nematologist Lee Aalders.

“They were also able to produce offspring at 13 months. Interestingly, no PPN were recovered from soil stored beyond the 13th month using the three-day misting technique.”

This means that given the right conditions, PPN in soil, which is carried on sea freight, footwear or used machinery, and protected from sun or extreme heat, will survive if they end up near a suitable host plant. This is a result that may not be detected using an extraction test like misting.

For quarantine officials around the world, this result is an important find, as it reinforces the risk associated with soil that, even though it may look sterile, unwanted nematodes may be present and undetected until paired with a suitable host plant.

“In the context of biosecurity, we think that the development of a generic test for plant parasitic nematodes – based around a molecular based bioassay — would enhance the probability of detection of PPNs and, therefore, prevent unwanted incursions beyond the border.”

Earlier this year, another AgResearch study into the survival rates of various transported soil organisms and published in Neobiota concluded that biosecurity risks from soil organisms are to increase with declining transport duration and increasing protection from environmental extremes.

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Original source:

Aalders LT, McNeill MR, Bell NL, Cameron C (2017) Plant parasitic nematode survival and detection to inform biosecurity risk assessment. NeoBiota 36: 1-16. https://doi.org/10.3897/neobiota.36.11418

Robust rattan palm assessed as Endangered, new Species Conservation Profile shows

An African rattan palm species has recently been assessed as Endangered, according to the IUCN Red List criteria. Although looking pretty robust at height of up to 40 m, the palm is restricted to scattered patches of land across an area of 40 km². It grows in reserves and conservation areas in Ghana and a single forest patch in Côte d’Ivoire. Its Species Conservation Profile is published in the open access Biodiversity Data Journal by an international research team, led by Thomas Couvreur, Institut de Recherche pour le Développement (IRD), France, in collaboration with the University of Yaoundé, Cameroon, Royal Botanic Gardens, Kew, UK, and the Conservatoire et jardin botaniques, Geneva, Switzerland.

The rattan palm is confined to moist evergreen forests with high rainfall, located at 100 to 200 meters above sea level. The species is poorly known, yet it is likely very rare judging from the limited amount of forest habitat remaining across its range. Furthermore, the known populations are isolated from each other by large distances, which makes them particularly vulnerable.

Even though there are gaps of knowledge concerning the rattan palm species, the research team conclude that it is most likely currently declining, due to habitat loss, fragmentation and over-harvesting. Often mistaken for a sister species, commonly used in trade, the stems of the endangered species are largely used in furniture production. When longitudinally split into ribbons, the canes are also used as ropes for thatching, for making baskets and sieves, and to make traps.

“As with most African rattan species, there is inadequate information on the international trade, but it is likely to be negligible,” explain the scientists.

“Conservation measures are urgently needed to protect the habitat of this species and to control the unsustainable harvest of the stems. A promising solution might be sustainable cultivation of rattans to avoid the exploitation of wild populations,” suggests Ariane Cosiaux (IRD), the lead author of the study currently based in Cameroon.

With their present paper, the authors make use of a specialised novel publication type feature, called Species Conservation Profile, created by Biodiversity Data Journal, to provide scholarly credit and citation for the IUCN Red List species page, as well as pinpoint the population trends and the reasons behind them.

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Original source:

Cosiaux A, Gardiner L, Ouattara D, Stauffer F, Sonké B, Couvreur T (2017) An endangered West African rattan palm: Eremospatha dransfieldii. Biodiversity Data Journal 5: e11176. https://doi.org/10.3897/BDJ.5.e11176