Cutting edge - What’s new in the world of botanical research?

Archidendron hendersonii Cryptocarya laevigata Sloanea woollsii

THE CUTTING EDGE

RESEARCHERS WORKING WITH THE AUSTRALIAN INSTITUTE OF BOTANICAL SCIENCE PUBLISH MORE THAN 90 PEER-REVIEWED ARTICLES EACH YEAR. DR BRETT SUMMERELL HIGHLIGHTS A FEW RECENT PROJECTS.

Argyrodendron trifoliolatum Emmenosperma alphitonioides Davidsonia pruriens

Pittosporum angustifolium Cynanchum elegans Dysoxylum fraserianum

UNDERSTANDING FAMILY TREES Researchers at the Australian Institute of Botanical Science invest considerable time and effort into understanding the relationships between plants – at a species and genus level, but also at a family and order level. The aim is to gain a better understanding of how different species are related to each other, and from this infer how they might respond to the environment, how they will adapt to changes in circumstances, and how they might fight off pests and diseases.

Given that most plant families are trans-continental, resolving the nature of these relationships usually involves collaboration between scientists in many countries.

Two recent papers1,2 have seen three of our botanists, Dr Marco Duretto, Margaret Heslewood and Dr Peter Wilson, play critical roles in determining the relationships in two extremely important plant groups in Australia – the family Rutaceae and the order Myrtales.

The Rutaceae is of course well known for the economically important genus citrus, but also contains many prominent Australian species such as boronia and zieria, whilst the Myrtales includes the Myrtaceae (which incorporates eucalyptus) and Onagraceae (fuchsia) families amongst others. The analyses are complex but involve morphological features, genetic information and DNA sequence and genomic data.

Both publications are the culmination of years of detailed collaborative work by dozens of authors located across most continents. The results not only elucidate the taxonomic placement of many unusual genera for the first time, but also provide a solid framework for future research. One of the more surprising results from the Myrtales study was that the closest genus to the eucalyptus group is the distinctive, large-seeded tropical rainforest species Lindsayomyrtus racemoides (Daintree Penda – a native to north-east Queensland, Moluccas, New Guinea and New Britain).

SEED BANKING RAINFOREST SPECIES Seed banking of rainforest species is hindered by a lack of knowledge as to which species are tolerant of desiccation and freezing. Dr Karen Sommerville and the team at the Australian PlantBank assessed a massive 313 different Australian rainforest species for seed banking suitability by comparing the germination of fresh seeds to those that had been dried at 15% relative humidity and stored at −20°C after drying.

The team compared desiccation responses to environmental, habit, fruit and seed characteristics, in order to identify the most useful predictors of desiccation sensitivity. They found3 that the likelihood of a species being sensitive to drying out was significantly increased by a species having a tree habit or having fleshy fruit with a high moisture content (or a combination of the two).

The responses observed in this study were combined with earlier studies to develop a simple decision key to aid prediction of desiccation responses in untested rainforest species.

GENOMICS GUIDES MANAGEMENT OF THREATENED SPECIES Owing to decreasing costs and increased efficiency, it is now conceivable that conservation genomic information can be used to improve the effectiveness of programs to aid the recovery for many, if not most, threatened plants species.

In a recent paper 4, Professor Maurizio Rossetto and the Research Centre for Ecosystem Resilience team highlighted how a simple genomic study could be used as a critical initial step in decisionmaking for conservation managers.

In the paper they provided biodiversity managers and conservation biologists with a simple, standardised workflow for genomic research that can guide efficient collection, analysis and application of genomic information across threatened plants.

They also used two case studies Banksia vincentia and Daphnandra johnsonii – to demonstrate how generating genomic information as early as possible can enhance conservation outcomes.

It turned out that Banksia vincentia was not a distinct species and did not warrant conservation, however, the opposite was true for Daphnandra, and genomic information could guide which individuals should be used to expand the population.

Zieria covenyi, a critically endangered member of the Rutaceae family

“The Rutaceae contains prominent species such as boronia and zieria.”

Paper details: 1. A new subfamily classification of the Citrus family (Rutaceae) based on six nuclear and plastid markers. TAXON, doi.org/10.1002/tax.12543. 2. A nuclear phylogenomic study of the angiosperm order Myrtales, exploring the potential and limitations of the universal Angiosperms353 probe set. American Journal of Botany, bsapubs.onlinelibrary.wiley.com/ doi/10.1002/ajb2.1699. 3. Assessing the storage potential of Australian rainforest seeds: a decision-making key to aid rapid conservation. Biodiversity and Conservation, doi.org/10.1007/s10531-021-02244-1. 4. A conservation genomics workflow to guide practical management actions. Global Ecology and Conservation, sciencedirect.com/science/article/ pii/S2351989421000421?via%3Dihub