Transverse section of Aristida pungens leaf (Image: A. Musson & E. Gray)
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Our year so far: internships at Kew

Three of Kew’s science interns reveal the projects they have been involved in during their 12-month placements, and explain how they have put into practice what they learnt at university

Blog team: 
Author: 
Eliza Gray, Bridget O'Boyle & Lucy Thursfield

 

Lucy Thursfield – Natural Capital & Plant Health

My work at Kew has been focused on analysing strawberry tree nectar to understand its benefits for bumblebees. Wild bee populations are declining dramatically; discovering which plant species provide the most nourishing nectar, and subsequently, which are the most beneficial to wild bees, can allow us to create pockets of nourishment in areas such as gardens, roadsides, and city parks.

The strawberry tree (Arbutus unedo) is known to be a brilliant food source for bumblebees. Its many flowers produce large volumes of nectar, which is especially attractive to queens. Unusually, flowers are produced during autumn, which is also when queen bumblebees gather food to hibernate over winter. Many queens can, therefore, be seen feeding on the tree at this time of year, especially the buff-tailed bumblebee (Bombus terrestris). However, exactly how nutritious A. unedo is, is unknown.  As queens are the founders of colonies, understanding how this vital food source impacts their health can potentially help bumblebee populations.

The strawberry tree, Arbutus unedo, at Kew Gardens (Image: L. Thursfield).

When strawberry tree nectar was previously analysed, scientists found a large amount of ‘unedone’, a compound found only in this tree. The structure of unedone suggests that it has antimicrobial properties; therefore, it may improve the health of bees by helping to manage disease and infection.

We can test this hypothesis by feeding unedone to infected bumblebees and observing whether the compound can combat infection. This study will use the infectious protozoan, Crithidia bombi, which is often found in B. terrestris queens and has been shown to negatively impact colony fitness.  

Large volumes of nectar are difficult to obtain by hand but fortunately, honeybees also feed on the strawberry tree and use the nectar to make honey. A. unedo nectar can, therefore, be bought from the local shop in the form of honey. I am currently working on isolating unedone from honey using techniques including LCMS (liquid chromatography–mass spectrometry) and HPLC (high-performance liquid chromatography).

If the feeding trials demonstrate that Arbutus unedo nectar can combat infections, then we can use this knowledge to create landscapes that benefit wild bumblebee populations.

Buff-tailed bumblebee queen feeding on the strawberry tree at Kew Gardens (Image: L. Thursfield).

Bridget O’Boyle – Natural Capital & Plant Health

As part of the Chemical Ecology and In Vitro Biology team, the main focus of my work has been studying traits that may lead to resistance against the beet leafminer (Pegomya hyoscyami): an increasing but little-researched threat to beet (Beta vulgaris) crops in the UK. This involves comparing the leaf chemistry of various beet cultivars as well as their wild relative, sea beet (Beta vulgaris subspecies maritima). Sea beet is a useful model because of its high genetic and phenotypic variability, and its ability to be crossed easily with cultivars.

I have found some chemical differences between wild and cultivated leaves; wild leaves appear to contain more higher-molecular-weight structures, such as saponins: a class of chemicals already known to deter insects. These findings will lead to future work isolating specific saponins to test against the leaf miners.

Damaged Beta vulgaris leaf just three days after infection by Pegomya hyoscyami leafminers (Image: B. O'Boyle).

Also on the pest resistance theme, I have been involved in research into the cotton moth (Helicoverpa armigera) and have recently prepared extracts of plants believed to have insecticidal properties. Analysis and bioassays will hopefully reveal whether the plants could be used in the field to discourage the cotton moth, a devastating pest.

Finally, and on a quite different note, I have started bioinformatics work with Michael Chester, aiming to identify structural rearrangements in Arabidopsis genomes. This work involves comparing short DNA sequences to a reference genome, an approach which has already been successfully applied to animal genomes. This is important work because variations may influence how characteristics are inherited, and, if successful, it would also be a step towards proving that this relatively simple method is viable in the study of plant genetics.

Being involved in so many projects is a really valuable experience, equipping me with a diverse range of skills. I am looking forward to the rest of my time here at Kew! 

Eliza Gray – Collections

My main project at Kew has been the digitisation of Kew’s extensive microscope slide collection. So far this has focused on digitising slides from the Poaceae (grass family) for a project which aims to identify C3-C4 photosynthetic intermediate genera within Kew’s collection. These intermediate grasses have started to evolve more efficient photosynthetic pathways, meaning they are better adapted to living in warm and arid environments.

Transverse section of Aristida pungens leaf scanned at 20x showing numerous vascular bundles, interrupted bundle sheath cells and bulliform cells, and hairs extending from the adaxial epidermis (Image: A. Musson & E. Gray).

Kew scientists are interested in understanding how the relatively inefficient C3 photosynthetic subtype evolved into the more efficient C4 subtype. Analysis of the intermediate C3-C4 grasses will allow us to identify the ‘stepping stones’ of evolution that occurred to give rise to the C4 lineages within the grass family. The majority of work within this field has been conducted on eudicots such as Flaveria, and our project aims to bridge the knowledge gap within the monocots.

There are distinct anatomical differences between the photosynthetic subtypes, and by scanning the Poaceae slides at 20x magnification, we aim to identify the differences that characterise those species within the C3-C4 intermediate stage. As grasses evolve from C3 towards C4 for example, they tend to have a higher vein density and enlarged bundle sheath cells (Sage et al. 2014).

Although this project is in its infancy, I’ve thoroughly enjoyed my involvement in it and I'm excited to continue working on it throughout my year at Kew!

- Lucy, Bridget & Eliza -


References

Sage, R. F., Khoshravesh, R. & Sage, T. (2014). From proto-Kranz to C4 Kranz: building the bridge to C4 photosynthesis. Journal of Experimental Botany 65: 3341–3365. Available online