Stopping to Smell the Flowers:
Exploring the genes that help plants make flowers.
Subject: Biology
Grade Level: 8-11
Timeframe: Approximately 1 week
Created by Margot Goldberg at the J. Craig Venter Institute, Summer 2015
Summary
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 is 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!
Key Concepts
NGSS Disciplinary Core Ideas (DCIs)
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HS-LS1.A Structure and Function
○ Systems of specialized cells within organisms help them perform the essential
functions of life.
○ All cells contain genetic information in the form of DNA molecules. Genes are
regions of DNA that contain the instructions that code for the formation of
proteins, which carry out most of the work of cells.
○ Multicellular organisms have a hierarchical structural organization, in which any
one system is made up of numerous parts and is itself a component of the next
level.
HS-LS1.B Growth and Development of Organisms
○ Cellular division and differentiation produce and maintain a complex organism,
composed of systems of tissues and organs that work together to meet the
needs of the whole organism.
NGSS Science and Engineering Practices
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Developing and Using Models
Analyzing and Interpreting Data
Constructing Explanations
Obtaining, evaluating, and communicating information
Overview of the 5E Structure of this module
Engage: Why do we care about flowers?
● Students engage prior knowledge of and emotional connection to flowers by recalling
when they have given or received flowers.
● Students connect prior knowledge and emotional connection (giving flowers to show love
and affection) to the biological purpose of flowers (sexual reproduction in plants).
● Teacher poses to students the utility of flowers to people (as necessary in generating
food), and threats to that utility (e.g., global climate change).
Explore: Arabidopsis as a model
● Students watch a time lapse video of a wild-type and a late-flowering mutant Arabidopsis
plant growing, then hypothesize about differences in growth pattern between the plants.
● Teacher reveals that the difference between the plants is in a gene.
● Students learn about Arabidopsis as a model organism that allows us to explore plant
genetics.
Explain: How do plants know when to flower?
● Students learn how to navigate Araport through a guided tour and learn about genomes,
gene function, and gene expression using the mutated gene from the plant video.
● Students use FLOR-ID, an Arabidopsis flowering gene database, to connect
environmental factors that affect flowering to the genes that interpret these signals.
● Students write a brief proposal for which flowering factor they would like to research.
Elaborate: How do environmental factors affect flowering at the molecular level?
● Students work in groups using FLOR-ID, Araport, and other tools to research a particular
flowering factor and flowering pathway genes.
● Students generate gene reports that become incorporated into a group presentation on
their flowering pathway to be given to members of “The Society for Flowering Plants.”
Evaluate: Communicating findings in a scientific conference
● Student groups present their research on their flowering pathway at the annual meeting
of “The Society for Flowering Plants” and also participate in judging their peers’
presentations.
● Student groups are evaluated on their presentations based on an assessment rubric.
○ Evaluation at the group level for the presentation
○ Evaluation at the individual level for gene reports
○ Peer evaluation of presentations may be incorporated
Learning Objectives
Overarching Questions
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What do genes do?
How do organisms respond to their environment?
How are genes involved in an organism’s environmental response?
Students will be able to:
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Explain the importance of flowering in plant reproduction
Identify and describe genes important to flowering in Arabidopsis using bioinformatics
tools
Use information gleaned from bioinformatics resources to explain how an environmental
input such as light or temperature can trigger changes in plant development
Present findings of bioinformatics research to an audience of peers
Materials
● Link to time lapse video of Arabidopsis wildtype and flowering mutant constans
https://www.youtube.com/watch?v=spkA1f5FmxY
● Link to flower dissection video from Exploratorium
https://www.youtube.com/watch?v=POYoFF6G8L4
● Link to Arabidopsis PREP video explaining Arabidopsis as a model species
https://www.youtube.com/watch?v=foHiKrlY9Qc
● Optional: Link to PREP video on P80 and signal transduction from the Gillaspy Lab
https://www.youtube.com/watch?v=5gyl_ODuZdY
● Powerpoint slides
● Handouts
● Devices for students (computers or tablets) to use for using Araport, FLOR-ID, and for
doing their research and/or creating their presentations.
Procedure
Day 1: Engage/Explore
Activate Prior Knowledge
Engage students’ prior knowledge by asking students about when they have given or received
flowers and collect their feedback at the board. Anticipate students will respond with holidays
like Valentine’s Day and Mothers Day.
At this point, have students read and discuss the following quote.
The flower is the poetry of reproduction.
It is an example of the eternal seductiveness of life.
-Jean Giraudoux
What does this quote mean? Why do plants make flowers? Connect students’ prior experience
with flowers being used as a show of affection towards significant others and parents with the
biological purpose of a flower: sexual reproduction.
Anatomy of a flower
***Enrichment option: This would be an excellent point to do a flower dissection lab if
time and materials permit. Otherwise, students may watch the video below in order to
gain some understanding of flower anatomy.***
At this point, students watch a video of Jalen, a high school Explainer at the Exploratorium in
San Francisco, dissect a flower and explain the purpose and reproductive parts of the flower.
Students then label a flower with male and female reproductive parts.
Importance for Agriculture
At this point, students may be wondering why flowers are important. Walk through the
presentation slides that match flowers to the fruits that they produce.
Present the Problem
At this point, students should understand that flowers are important to food production.
Flowering plants make up the vast majority of food crops. However, with global climate change,
the conditions for crops in a given area are changing rapidly. In some areas of the US, there is
too little water, and in others, there is too much. We expect that the average temperature is
going to increase significantly in the coming years. Furthermore, in coastal areas there may be
an increase in salinity of water as sea levels rise.
One of the issues that farmers face is getting their plants to flower and set fruit at the right time
in order to get a good harvest.
Observations of two Flowering Plants
Show the video of a wildtype and constans mutant to students and have them make
observations about what they see during the video.
Ask students why they think that the two plants look so different from one another and chart
their observations on the board (there is a slide provided for this purpose). Anticipate that they
may say that one had more light or more water (different growing conditions).
Some Anticipated Observations
Wild Type
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smaller plant
smaller rosette (leaves at the bottom
of the plant)
bolts first (creates its inflorescence)
Creates many siliques (pods)
constans mutant
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larger plant
very large rosette
bolts very late
Inflorescence has many cauline
leaves, fewer flower
After charting the students’ observations, explain that they are both receiving the same water,
light, and other growing conditions to the best of the grower’s control.
Explain to students that there is one important difference between these two plants: they differ
in a single gene.
Exit slip: What is your response to the difference between these plants? Were you
surprised or not? Do you believe it or not?
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Day 2: Explore/Explain: Meet Arabidopsis! and Using Araport to look at genomics, gene
function, and gene expression
One nice touch for this slide
would be to use a picture of
your own students doing a drill!
Anticipate that students will say these players are doing a drill. This image shows players doing
a drill exercise to build speed and agility for a game. In a way, they are modeling and building
the types of skills that they will need in order to be successful for a game by taking one or a few
pieces of their game (agility, speed) and working to improve them. This is similar to what
scientists do when we study a model organism: we use that organism to look at some aspects
of biology that we are trying to understand, then take the things that we learn and apply them to
our bigger conceptual understanding or more important systems (like using a mouse to study a
human disease, or Arabidopsis to study the genetics of food crops).
Chart the students’ responses on the board, then show this slide in order to get them to connect
their understanding of drills to the ways that scientists use model organisms.
At this point, ask students about the plants they saw in the video. Had they seen those plants
before? Anticipate that they have not. Tell the students that the plant is called Arabidopsis, and
that it basically a weed. However, it is our model
organism for understanding how plant genomes
work. Then show the PREP video on Arabidopsis
in order to introduce students to the plant and how
and why it is used as a model organism.
Mutant vs. Wildtype
The video introduces the concept of mutant vs.
wildtype plants. After watching the video, ask
students to guess which plant was mutant and
which plant was wildtype from the time lapse
video, then show students the blurb at the bottom
of the time lapse video that shows the mutation so they can record the name of the mutated
gene (constans).
Now that we know what gene was mutated, how can we find out more about it? It’s time
to introduce Araport.
1. Comparison of Araport to Google: What types of information can you get from each?
2. Look up our gene of interest (constans) in Araport and go through the tutorial. Walk
through the tutorial together with your students and check to see that they are able to
access Araport.
3. Dissecting a gene page. Look at the menu at the top of the Gene Page and focus on
Genomics, Function, and Expression.
a. Genomics: Where in this gene “written” in the genome?
b. Gene Function: What does this gene do?
c. Gene Expression: Where and when does this gene do its job?
4. Genomics
a. The window under genomics shows where the gene is in the genome.
b. If you click on the gene within the window, it will pull up the gene sequence.
c. You can also find out other information, like which chromosome the gene is on,
neighboring genes, and the introns and exons within the gene.
5. Function
a. This section shows Gene Ontology (GO) terms, which describe the gene’s
biological, cellular, and molecular characteristics.
b. Most of these GO terms will be unfamiliar to students, but they may connect
some of them (such as flower development) with what they know about what
effect constans had when mutated.
6. Gene Expression
a. Start students off here by connecting gene expression to expression in general.
What does it mean to express yourself?
b. Grow the analogy by extending it to a familiar example: marching bands. What
happens if the band members decided to express themselves without listening to
or caring about what their bandmates played, or instead of marching in formation,
decided to do their own thing without looking at they others?
c. Development map: students break down the expression map. What do the colors
mean? Where and when do all of these parts of the plant grow? The redder the
plant part, the more mRNA for that gene is in that tissue. Yellow means there is
little to no mRNA for that gene in that tissue.
d. Shoot apex: What is it? Why is it important? The shoot apex is where the plant is
actively growing new leaves and tissue. This is also where the inflorescence, or
flowering stem, will come from. When the shoot apex is vegetative, the plant has
not yet decided to bolt and flower. It then transitions from vegetative growth to
floral or inflorescence growth. Therefore, since constans is involved in the switch
between vegetative and floral growth, it makes sense that it would be most highly
expressed in the shoot apex transition, where that decision to flower is being
made.
Day 3: Explain: How do plants know when to flower?
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?
Anticipate that students will say that plants normally flower in the spring and summer, and that
some factors that might be involved are temperature, light, and water. Chart student responses
on the board. You will want to save these ideas for when students are looking at FLOR-ID’s
flowering factors.
Since yesterday, we were looking at a gene involved in flowering, and we are pretty sure that
there are environmental factors that also determine flowering, now is a good time to ask:
How might genes be involved in the decision to flower?
This is the perfect time to introduce FLOR-ID: an Arabidopsis database devoted solely to
flowering genes. FLOR-ID has clear, interactive illustrations of flowering pathways that show
how environmental and internal inputs set into motion the molecular sequence of events that
lead to flowering.
1. Direct students to FLOR-ID: www.phytosystems.ulg.ac.be/florid/
2. Have students explore the site for about 5-10 minutes and take notes, write down
impressions. You may want to point them to the overview pathway as a starting point,
since this is the master pathway from which students may navigate to more specific
pathways. http://www.phytosystems.ulg.ac.be/florid/networks/whole
3. Encourage students to draw, take notes, and ask questions about what they find.
At this point, put the overview pathway on the board and point out constans on this pathway,
and the fact that it is controlled by the environmental input of photoperiod. At this point, showing
the video from the Gillaspy lab about how environmental factors influence plant growth.
https://www.youtube.com/watch?v=5gyl_ODuZdY
Have students work in groups to break down the legend of the overview pathway, then come
together as a class to discuss the pathway. It might be helpful to extend the analogy of a football
play sheet or a flow diagram to make sense of the legend items and the logic of the overview
diagram.
Finally, have student work in groups to make sense of the environmental input boxes in the
overview pathway. Discuss what these factors mean as a whole class (as the teacher, you can
facilitate that discussion help clarify what these factors mean as necessary.
Flowering Factors
What this input is
Photoperiod
The length of daylight and nighttime in a given 24 hour
period.
Sugars
How much sugar is available to the plant: they need the
energy from sugars to drive flowering.
Ambient Temperature
Vernalization
How warm or cold it is.
Arabidopsis seeds need to experience a period of cold
before they will sprout. The period of cold in the wild is
usually winter, but in the lab, vernalization is induced by
storing seeds in a refrigerator for a few days to a week.
Vernalization may also refer to biennial plants that need to
experience cold in order to flower in their second year.
Aging
Hormones
Circadian Clock
Getting older!
Plants have hormones, too! They are different chemicals
than animal hormones, but they have similar functions in
signalling important processes such as growth, ripening,
and the leaf senescence, or falling. The hormones in the
picture are GA or gibberellic acid, a plant growth hormone,
and CKs or cytokinins, which play a role in cell cytokinesis
and growth.
Like people, plants have an internal clock that helps
regulate biological processes over the course of a daynight cycle.
Allow students to decide as a group which of the inputs they find the most interesting. Have
students pick their top factor, then write a proposal on that pathway. Between this class and the
next class meeting, where you continue this module, assign each student group a flowering
factor to study further.
Day 4: Research
Give students time to research their flowering factors. Give students a rubric for assessing the
presentations as well as a page for each student to complete a gene report for a gene in their
particular pathway. This scaffold will help them to organize the information that they find about
the gene they have chosen to research.
Note that groups will each give one presentation, but each student is individually responsible for
one gene report. Also included is a presentation template that may be given to students as a
starting point for making their presentations. This template is based on the factors required in
the assessment rubric.
Students will need to use both Araport and FLOR-ID to complete this work; encourage them to
work together to understand their flowering factor by exploring it on FLOR-ID and doing outside
research on other sites, including Wikipedia. They may then take genes that appear in FLOR-ID
for their flowering factor and search them using Araport in order to generate the gene reports for
their presentations.
As students work on their research, circulate through the room to assist them. Students may
need to do additional research outside of araport.org and FLOR-ID in order to get all the
information they need to present the flowering factor they are researching. Be sure that they are
collecting their sources in a works cited slide.
Day 5-Day 6: The Annual Meeting of the Society for Flowering Plants
Students give their presentations. Allow students a little time at the beginning of the two class
periods to make last minute adjustments to their presentations.
Students who are listening to the presentations are expected to be taking notes and rating the
presentations. These ratings may be tabulated in awarding prizes to students.