Flowering is an essential part of a plant's life cycle, and getting the timing and placement of flowering right can mean the difference between making lots of seeds for the next generation (success!) and none at all (EPIC fail). In this lesson, students will explore the genes that help Arabidopsis plants decide that it's time to make flowers. Once a plant makes the decision to flower, other genes must signal the right parts of the plants to develop into flowers. When this signaling is interrupted, very strange things can happen! Stay tuned to find out more about this lesson.

1. L E S S O N 2
FLORAL DEVELOPMENT

2. Warm Up
1. When do plants normally flower?
2. What are some factors that you think plants use to
decide that it is time to flower?

3. What was that plant from yesterday?
Had you seen the type of plant that was growing in
the video from yesterday?
https://www.youtube.com/watch?v=foHiKrlY9Qc

4. The plant on the right has a mutation in its
DNA that causes it to grow differently

5. Arabidopsis (Thale Cress)
• Small, fast-growing relative of
broccoli, cauliflower, and
mustard
• First plant genome sequenced
• Small genome: only 5 pairs of
chromosomes (people have 23
pairs)
• Scientists use Arabidopsis to try
to understand the biology of
other plants, and even humans.

6. Arabidopsis (Thale Cress)
• Small, fast-growing relative of
broccoli, cauliflower, and
mustard
• First plant genome sequenced
• Small genome: only 5 pairs of
chromosomes (people have 23
pairs)
• Scientists use Arabidopsis to try
to understand the biology of
other plants, and even humans.
Many experiments have
already been done on
Arabidopsis!

7. If many scientists have been
working to understand Arabidopsis
for a long time…
How can you find out what we
have already discovered about
Arabidopsis?

8. Araport: Google for Arabidopsis

9. What happens when you put “flower” into
Google
What categories of information do I want?
How many results are there?
Question: What would
you click here if you
only wanted pictures of
flowers?

10. What happens when you put “flower” into
Araport?
Question: What would
you click here if you
only wanted genes that
are involved in
flowering?

11. Comparing Google and ThaleMine
If you click on any one of these
categories, you will only get results
of the type that you requested.
Example: if you click on “Images”
in Google, you will only get picture
results. If you click on “Gene” in
Thalemine, you will only get gene
results.
How many gene hits did we get by
putting in the search term “flower?”

12. Finding the Mutated Gene in Araport
We can search for the gene, constans, that was
mutated in the plant that we saw above, in order to
see what kind of information we can find about it.
1. Enter constans into Araport.
2. Once you get the results, filter them so you only
get gene hits.

13. Finding the Mutated Gene in Araport
We can search for the gene, constans, that was
mutated in the plant that we saw above, in order to
see what kind of information we can find about it.
1. Enter constans into Araport.
2. Once you get the results, filter them so you only
get gene hits.

14. Finding the Mutated Gene in Araport
We can search for the gene, constans, that was
mutated in the plant that we saw above, in order to
see what kind of information we can find about it.
1. Enter constans into Araport.
2. Once you get the results, filter them so you only
get gene hits.

15. Finding the Mutated Gene in Araport
We can search for the gene, constans, that was
mutated in the plant that we saw above, in order to
see what kind of information we can find about it.
1. Enter constans into Araport.
2. Once you get the results, filter them so you only
get gene hits.

16. Finding the Mutated Gene in Araport
We can search for the gene, constans, that was
mutated in the plant that we saw above, in order to
see what kind of information we can find about it.
1. Enter constans into Araport.
2. Once you get the results, filter them so you only
get gene hits.

17. Finding the Mutated Gene in Araport
We can search for the gene, constans, that was
mutated in the plant that we saw above, in order to
see what kind of information we can find about it.
1. Enter constans into Araport.
2. Once you get the results, filter them so you only
get gene hits.

18. constans Gene page
Once you click on the constans gene page, there is
A LOT of information! Let’s focus on three types of
information about constans:
Genomics, Function, and Expression

20. Genomics: Where is this gene “written?”
Genomics shows where in the genome the constans
gene is. You can scroll around to find genes that are
nearby.

21. Genomics: Where is this gene “written?”
Genomics shows where in the genome the constans
gene is. You can scroll around to find genes that are
nearby.
You can also click on the gene to see its DNA code or sequence.

22. Genomics: Where is this gene “written?”
Genomics shows where in the genome the constans
gene is. You can scroll around to find genes that are
nearby.
You can also click on the gene to see its DNA code or sequence.

23. Function: What does this gene do?
In this section, you can look at what we think this
gene actually does in the plant through brief
descriptions called Gene Ontology or GO terms.

24. Function: What does this gene do?
Can you find any GO terms on the
list that match up with what you
saw in the video?

25. Expression: Where does this gene work?
This map shows where
(and when!) the
constans gene is
being expressed.
This information is
gathered by
measuring the mRNA
transcripts of the
constans gene in all
of the plant parts
shown in the image.

26. What is gene expression?
What does it mean to express yourself?
A gene is encoded in DNA in the nucleus of the cell.
In order for DNA’s message to be “heard” and
executed in the cell, mRNA copies of the gene need
to be made. How many mRNA copies of a gene that
are made determines the level of gene expression.

27. Gene Expression Analogy
Every gene must be
expressed in the right
place and at the right
time in order for an
organism to to function
well.
Similarly, each member
of the marching band
needs to be in the right
place, at the right time,
and playing the right
note for us to see the T
Rex and hear the music.

28. It matters WHEN, WHERE, and HOW
MUCH genes are expressed.
Would you tell someone goodnight at 9 a.m.? Would
you say “congratulations” to a friend who just lost a
basketball game?
It is not good for all cells in an organism to express all
their genes at one time. Each type of cell has a
different “expression profile that describes

29. What happens if genes are expressed in the
wrong place, or at the wrong time?

30. What happens if genes are expressed in the
wrong place, or at the wrong time?
When gene expression goes
wrong, it’s kind of like saying the
wrong thing at the wrong time.
Awkward, right?

31. What happens if genes are expressed in the
wrong place, or at the wrong time?
When gene expression goes
wrong, it’s kind of like saying the
wrong thing at the wrong time.
Awkward, right?
*Sigh* I know what you mean, dude.

32. What happens if genes are expressed in the
wrong place, or at the wrong time?
When gene expression goes
wrong, it’s kind of like saying the
wrong thing at the wrong time.
Awkward, right?
*Sigh* I know what you mean, dude.
This fly has legs where its antennae should
be because a gene that normally tells
tissue to become legs is accidentally
expressed where the antennae should be.

33. Expression: Where and when does this gene
work?
This is a developmental
map of Arabidopsis. You
can see some familiar
structures, like leaves
and stems.
There are also some new
structures, like siliques,
which are like seed
pods, and the shoot
apex, which is where the
plant grows most
actively.
RED = lots of expression

34. IMAGE CREDITS
• https://commons.wikimedia.org/wiki/File:Small_Red_Rose.JPG
• https://pixabay.com/en/tulip-flower-white-and-red-green-754304/
• https://pixabay.com/en/flower-daisy-spring-766120/
• https://commons.wikimedia.org/wiki/File:Jean_Giraudoux_1927.jpg
• https://commons.wikimedia.org/wiki/File:Strawberry_flower_and_guest.jp
g
https://commons.wikimedia.org/wiki/File:Navionics_Strawberry_Team.jpg
• https://commons.wikimedia.org/wiki/File:Pine_Apple_Flower.jpg
• https://commons.wikimedia.org/wiki/File:Honeycrisp-Apple.jpg
• https://commons.wikimedia.org/wiki/File:Navionics_Pineapple_Team.jpg
• https://commons.wikimedia.org/wiki/File:Banana.png
• https://commons.wikimedia.org/wiki/File:BananaFlowerOcotepec.JPG
• https://pixabay.com/en/flower-apple-tree-vernal-tree-93036/
• https://commons.wikimedia.org/wiki/File:Arabis_thaliana_Sturm6.jpg