The Origin of the Beefsteak Tomato
Have you ever wondered how plants grow? You might have known that in humans a special tissue called a growth plate exists at the end of each long bone in children and adolescents. This growth plate contains special cells called osteogenic cells that are responsible for dividing and adding more bone cells to existing bones thereby making them longer. Plants grow is a very similar fashion. However, in plants, the tissue where growth originates is called the meristem. Meristems contains un-specialized cells called stem cells. Similar to osteogenic cells, these stem cells continuously divide allowing plants to grow and form new organs. Plants contain different meristematic regions that control the growth in the region they are found. One particular region called the shoot apical meristem gives rise to specialized plant organs such as leaves and flowers. However, when these specialized organs are formed, the shoot apical meristem must produce more stem cells in order to replace the ones it lost as these organs developed. In tomatoes, stem cell production in the shoot apical meristem is controlled by a negative feedback loop involving two important genes called WUSCHEL (WUS) and CLAVATA (CLV). WUS promotes stem cell formation and is therefore responsible for replacing the cells that have been lost due to organ formation while CLV is responsible for repressing WUS activity thereby inhibiting stem cell production. This negative feedback loop therefore regulated the production of stem cells in the shoot apical meristem and an overproduction of stem cells in this region.
The discovery of the genes responsible for maintaining meristem size and therefore fruit size in tomatoes is significant because it can help agricultural breeders adjust the size of fruit in fruit-bearing plants. For example, wild tomato plants originally bore tiny, “berry-sized” fruits. However, a mutation in the CLV3 gene lead to an increase in tomato size. Plant cultivators artificially selected for this mutate making this mutant more common which is why we harvest larger tomatoes today. Therefore, understanding the pathway that leads to larger fruit size can allow breeders to customize fruit size in tomatoes and other fruit bearing plants.
Figure 1: Genes controlling stem cell production in tomatoes are responsible for the increase in tomato size.
Link: https://phys.org/news/2015-05-genes-stem-cells-revealing-beefsteak.html
Posted by: Katie Kossack
I thought that it was very interesting that the comparison between how human bones grew and how plants grow was very interesting. I was always curious to learn the process behind picking the genes to target in genetically modified fruits and veggies. It was interesting to learn that the gene usually being targeted at least in tomatoes is the gene that controls the meristem size. I wonder what are the other genes that are being targeted in other genetically modified fruits and veggies.
ReplyDeletePosted by Leah DeLorenzo (group A)
I also thought it was interesting to learn about the mechanism behind plant growth. In some crops, certain genes are intentionally mutated to produce a desirable trait. However, the mutation that led to the beefsteak tomato was actually a random mutation that increased the size of the tomato and was therefore artificially selected for by farmers.
DeletePosted by: Katie Kossack
Before reading this article, I never thought of how much similarity there was between human bone growth and that of a plant. This article brought attention to a controversial topic that I heard about from another professor with tomato growth. The biggest property farmers prioritized was size of the tomato, thus breeding larger tomatoes each generation. However, what they did not know was that the tomato was losing all the other essential qualities such as taste, or nutritional value. Combining with what you summarized in the article, it makes ground-breaking results to enhance a tomato that has all the proper nutrients/taste combined with size. I wonder if modifying the meristem and size of the tomato do have an effect on these other properties though.
ReplyDeletePosted by Andrew Do (group A)
I think you brought up a really interesting point. I am not sure if this particular mutation that led to the increase in tomato size had any other effects on the tomato. I know in some crops, certain genes are intentionally mutated or introduced from other unrelated organisms to enhance certain plant traits and this very well could cause other effects on the plant's genome. However, the mutation that this paper is discussing was a mutation that occurred naturally in tomatoes and was artificially selected for its size.
DeletePosted by: Katie Kossack
This is an interesting topic and it's important to understand that many of our cash crops were originally tiny, I'll get to why in a second. If you look at corn thousands of years ago, it looks like a pea pod that's got that whole geometry thing figured out. It wasn't until after generations upon generations of artificial selection that we eventually arrived at the kernel studded monolith we all know and love. Why is this important for the general public to understand? So that they aren't so reactive to the acronym that is the Whole Food's shopper's kryptonite; "GMO". Ever since agriculture became in vogue, we've been systematically modifying organisms in a genetic fashion, which makes the phrase "Genetically Modified Organism" too much of a vague boogie-man to do any good. If there's to be a cause for concern, it should be with the method through which the organism has its genes modified, not the fact that they have been modified.
ReplyDeleteThe phrase is annoying, as it creates an unnecessarily elitist (not like elitism is ever necessary though) culture centered around policing other people's shopping baskets. It's especially problematic since not everyone can afford the more expensive, trendy non-GMO products that people in Canada Goose jackets insist they buy. Clearly, this confusion, brought about by an ambiguous acronym and the incessant need for people to be exclusive (even over something as mundane as grocery shopping), shows a gap in our education system, but I'm sure ol' Betsy will clear the air in the years to come.
Posted by Owen Mulledy
I definitely agree that there is a huge misconception around the term GMO. I think a lot of people when they hear the term "GMO" are concerned about trans genetic crops, which is a type of GMO in which genes are taken from other unrelated species and inserted into the genome of crops to produce desirable traits. I think people are uncomfortable with idea of having certain genes inserted into the genomes of the crops we consume because they see this as being very unnatural and how these inserted genes interact with the rest of the genome remains unclear.
DeletePosted by: Katie Kossack