Macaranga sp.

Today starts the annual series featuring research at the University of British Columbia as part of Celebrate Research Week. Note: the photograph of the plant was not submitted as part of the entry, but I added it for illustrative purposes: Macaranga peltata by J.M. Garg of Wikimedia Commons.

Lindsay introduces Dr. Reinhard Jetter:

Dr. Reinhard Jetter is an Associate Professor with joint appointment in both the Botany and Chemistry Departments at UBC. He also holds the Canadian Research Chair in Natural Plant Products. His research projects focus on plant biochemistry, especially on the mechanisms with which plants defend themselves against herbivores and adverse climatic conditions.

Dr. Jetter writes:

We use gas chromatography and mass spectrometry to analyze the chemical composition of plant surfaces. The chemical profiles differ greatly between species and between different organs of the same plant, in some cases even within one organ – for example between the upper and the lower sides of the same leaf. This can be seen in one of our projects where we found that the leaves of diverse Macaranga species are covered with compounds forming a smooth coating (first image via scanning electron microscope), whereas the stems of the same plants exhibit a surface that is very rough due the presence of microscopic crystals (inset image).

The crystals make those stem surfaces slippery for walking insects, and so help to protect the plant against many small herbivores. Slippery surfaces are difficult to scale only when they are inclined or even vertical, but would be useless on horizontal organs. So it makes a lot of sense that the plants make crystals only for the stems and not for the leaves. How do plants manage to be so efficient in the use of this defence mechanism? We found out that the slippery crystals consist of special compounds called triterpenoids, which are very similar to cholesterol. They are being made solely for this purpose, and we are currently investigating the genes and enzymes involved in their synthesis.

In other projects, the Jetter lab is studying the biochemistry of skins of crops (rye, tomato) and model species such as Kalanchoe daigremontiana ( commonly known as “mother of thousands”) and Arabidopsis thaliana (thale cress). We want to understand how each species makes and accumulates different chemical compounds at the surface of its organs, and what their individual biological functions are.

Daniel adds: As an aside to local readers, I’ll be giving a lecture on Monday: Biodiversity of Southern Alaska and Yukon. This is part of our education theme for this month on “Biodiversity and the North”. The BPotD series on the topic will take place later in March.

Macaranga sp.
Macaranga peltata

3 responses to “Macaranga sp.”

  1. lisa

    Wow! I can already tell I’m going to love this next week of entries. There is so much to learn about plants, and their strategies for dealing with a hostile world while rooted in the same spot. We fight or flee: they produce intricate patterns of slippery crystals, among other things, in defense. Thank you for such an interesting topic.
    Cheers

  2. elizabeth a airhart

    you all do make my day and some of my night
    i too look forward to this week dr jetter
    the write up above mentions the study of
    tomatoes our crops here in florida took
    a real hit from the freeze will your
    studies help the growers ? in some way
    it will be very cold in the north tonight
    thank you for shareing

  3. mtn laurel

    Awesome! I had the chance to take a SEM seminar last semester – it opened up an amazing world of the structure of plant surfaces. Many have amazing defense mechanisms.

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