Why plants can be great models for studying genetics

Gregor Mendel studied the inheritance of a number of pea traits including seed colour (yellow or green) and seed shape (smooth or wrinkled).

Gregor Mendel studied the inheritance of a number of pea traits including seed colour (yellow or green) and seed shape (smooth or wrinkled).

In 1866, a paper on the inheritance of traits in pea plants was published. The author was Gregor Mendel, a monk living in Brno (now in the Czech Republic). In the paper Mendel described how traits such as pea seed colour (yellow or green) and seed shape (smooth or wrinkled) were inherited and by doing so he built the foundations for modern genetics. Unfortunately, the paper stimulated little interest and Mendel died in 1884 with his scientific work largely unknown. It wasn’t until the early 1900’s that his work was rediscovered and more fully appreciated. It was supported by a number of prominent scientists of the time including William Bateson (the first director of the John Innes Horticultural Institution), who coined the term “genetics”.

For anyone unfamiliar with Mendelian genetics I recommend watching this video by Hortensia Jiménez Díaz for TEDEducation:

(I should say here that as a plant biologist I don’t approve of the concept of pea “marriage” but you get the jist!)

I don’t think it is coincidence that the laws that form the basis of modern genetics were discovered from work done on plants. There are a number of properties that aided Mendel’s work and make many plants ideal for use in genetic studies.

Many plants are self fertile

Before Mendel carried out cross fertilizations between pea plants he first ensured that the peas he used were from true breeding lines, meaning that the lines always produced the same trait, for example yellow seeds. This is possible because peas (like many plants) have both male and female sexual organs on the same plant and are self-fertile. Over generations of self fertilization the lines will have a tendency to become homozygous for traits (alleles) resulting in the YY and yy parent genotypes (described in the video) for yellow and green seeds respectively.

Cross fertilization is relatively easy

Simply a matter of getting the male and female sex cells together. For flowering plants artificial transfer of pollen onto the female part of the flower is often pretty straightforward. It is generally a lot messier and requires more effort to cross fertilize animals (the recently announced “possible” pregnancy of an Edinburgh Zoo panda is due to artificial insemination after the two pandas failed to mate).

Large numbers of offspring

Plants produce large numbers of offspring compared to many animals so it is possible to acquire sufficient numbers of offspring from crosses to analyse inheritance of traits.

Seeds can be stored

Seeds are storage vessels for genetic information. They can be kept for extended periods of time and then germinated and grown when it suits the scientist.

Short life cycles

Many plants have relatively short life cycles. For example the model plant Arabidopsis thaliana can complete its life cycle in about 8 weeks so it is possible to progress through generations relatively quickly. A. thaliana is also a very small plant so can be grown in large numbers cheaply.

Arabidopsis thaliana plants next to a US 1 cent coin. Image by BlueRidgeKit distributed under a CC-NC-SA licence

Arabidopsis thaliana plants next to a US 1 cent coin. Image by BlueRidgeKit distributed under a CC-NC-SA licence

Needless to say these properties don’t apply to all plants. It would be much more difficult to perform genetic studies on oak trees than a little weed plants like A. thaliana. There are also many plants that go to great lengths to avoid self-fertilization (for an example check out my post on Primula vulgaris). Nevertheless, studies on plants that have some or all of these characteristics can be (and have been) very useful for understanding genetics, and this knowledge can then be applied to other organisms.

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3 thoughts on “Why plants can be great models for studying genetics

  1. These properties that aided Mendel’s work are also (almost exactly) the reasons why we chose C.elegans for modern genetic studies.

  2. Yes C.elegans has hermaphodite forms right? Another advantage to working with plants i didn’t mention is that with many species we can generate stable transgenic lines – can this be done in C. elegans?

  3. Pingback: Morsels for the mind – 23/8/2013 › Six Incredible Things Before Breakfast

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