The Model plant

Hello, and welcome to the first of my new blog series, which is going to be all about plant science. In this series I want to write about plant science- what plant scientists do, the basics of some of the experiments we carry out, and interesting things about plant science.

In this post I will be introducing you to Arabidopsis, one of the most widely studied plants.

The model plant:

There are a lot of different plants that scientists work on, but the most common plant to be studied is Arabidopsis thaliana.

What is Arabidopsis?

Arabidopsis is a small flowering plant which is part of the Mustard (Brassicaceae family). The mustard family is made up of over 3500 species, and includes many plants of agriculturally important plants such as Cabbage, Broccoli, Brussel sprouts and Kale.

Gouache-arabidopsis-thaliana

Source: Wikimedia

Why is it a model plant?

Arabidopsis has been widely studied genetically, biochemically and physiologically. This is because Arabidopsis has several traits which make it great for lab work:

  • It doesn’t need much to grow: light, air, water and a few minerals are all Arabidopsis needs to grow well.
  • It is pretty small (20-25cm tall)
  • Its easily grown in greenhouses, and incubating chambers
  • It has a short lifecycle: It can complete its life cycle in just 6 weeks, with flowers being produced after 3 weeks.
  • The flowers naturally self-pollinate, which aids in genetic testing.
  • From one plant you can get thousands of seeds.
  • It has one of the smallest genomes among plants, of just 135 mega base pairs, and 5 chromosomes: which makes it relatively easy to genetically manipulate, map and sequence.
  • It is a diploid, meaning it has two copies of each chromosome- one from the Mother and one from the Father.  Many plants are polyploids and have multiple sets of chromosomes- for example Bread wheat is a hexaploid with 3 complete genomes. Being diploid makes studying genetics in Arabidopsis much simpler.
  • Its genome has been fully sequenced, and a lot is known about the functions of its genes and proteins.
  • Genetic transformation of Arabidopsis has been performed for ages, and the method for transformation is well established. (note: A post on transformation will be coming soon).
  • There is a huge library containing mutants of Arabidopsis, which have defective aspects of plant growth and development, the underlying genetics of a lot of these mutations have been identified.
  • Its well suited for microscopy

What are model plants used for?

Model plants are used to test out hypotheses quickly and efficiently.

Although Arabidopsis is not an important plant for agriculture, it shares many features with agricultural plants such as flowering mechanisms. 

Why is this Important?

Agricultural plants are extremely important to us.  Bread wheat for example, is one of the three most globally important crops, accounting for 20% of the calories consumed by people worldwide. 

However, many agricultural plants, like Wheat, are really hard to study:

They have huge genomes, Bakers wheat has a genome of 17GB:  it has 17,000,000,000 base pairs.  This is HUGE. In comparison, the Human genome only has 3,000,000,000 base pairs.

In addition, Wheat is hexaploid. Wheat has 6 copies of each of its 7 chromosomes giving it a complete set of 42 chromosomes.  The human genome is made of 23 pairs of chromosomes, giving it  a total of 46 chromosomes. 

The Wheat genome is crazy complex, and really tricky to study. Arabidopsis on the other hand, is pretty simple.

And, given the fact that Arabidopsis has so many similarities to wheat… why not study things such as  the mechanisms of flowering of Wheat==> in Arabidopsis? Studying these mechanisms in Arabidopsis removes the complexity of the wheat genome, and time restrictions (wheat takes about 3 months to grow) associated with wheat research.

This is why so many plant scientists LOVE Arabidopsis so much.

 

References:

http://www.wheatgenome.info/

https://www.cshl.edu/news-a-features/bread-wheats-large-and-complex-genome-is-revealed.html

http://science.sciencemag.org/content/282/5389/662.full

Extra reading:

For keen beans wanting to find out more about Arabidopsis, there has been a 3 part series all about Arabidopsis published by the JIC:

https://www.jic.ac.uk/news-and-events/blog/

Feature image source: https://www.flickr.com/photos/tico_bassie/429882778

 

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