To know a plant, grow a plant!
We've received quite a bit of e-mail from folks planning for the artificial selection lab and wondering about what seeds to order. Here are some thoughts about that:
The AP Biology artificial selection lab materials list suggest using Fast Plant seeds C1-122--the C1-122 seedstock number is from our Rapid-cycling Brassica Research Collection (RCBC) at UW-Madison.
C1-122 is an F1 seedstock of B. rapa used for illustrating Mendelian inheritance patterns, and we understand the rationale for wanting a way get double-duty out of the time spent growing plants--to simultaneously conduct selection and genetics investigations using the same population of plants. However, there are a few things to consider:
First, C1-122 is an F1 dihybrid stock that comes from a cross of homozygous nonpurple stem (anl, anl) with homozygous purple (ANL, ANL) and homozygous yellow-green leaf (ygr,ygr) with homozygous green leaf (YGR, YGR) . Phenotypes of F1 plants are wildtype, purple, anl/ANL, normal green,YGR/ygr Instructors ought to consider carefully if they really want to use a dihybrid or not. That would not be our first choice for a selection lab unless you are planning to also use the plants to teach Mendelian inheritance patterns. Standard seed is vigorous and has lots of variation from which to select traits for a breeding experiment.
Another important consideration is that our Rapid-cycling Brassica Research Collection (RCBC) at UW-Madison, is a tiny organization that we run to support ongoing Brassica plant breeding research and supply small numbers of seeds to researchers. Our research collection does not get involved with orders and shipping for this type of educational use; that is far beyond our capacity; however, high quality seed is available commercially. Seeds of the C1-122 type are available from Carolina Biological directly http://tinyurl.com/cb8ku6n or through Amazon.com http://tinyurl.com/7raq2zk Standard seeds can be purchased here: http://tinyurl.com/89xmzqr
If you do have some experience already with Fast Plants and do want to use a mono- or dihybrid stock to get double-duty from this lab, teaching both the selection inquiry and genetics lessons, it would be best to consider all the options--monohybrid vs dihybrid and which phenotypic characteristic would work best for your situation (e.g. nonpurple stem, rosette-dwarf, yellow-green leaf, tall plant etc.). Descriptions of the primary Brassica rapa seedstocks are available on our website at http://fastplants.org/resources/kinds_of_plants.php
The inherited trait(s) of interest that you choose to have students work with needs to be determined in part by how you intend to have students grow out their F2 offspring: will they plant seeds in potting mix and grow seedlings to look for inherited traits, or will they germinate their F2 seeds in a Petri dish? Purple/nonpurple stem and rosette-dwarf can be detected in seeds germinated in Petri dishes; however, the yellow-green leaf trait cannot be discerned.
One can also consider choosing seedstocks for these lessons that illustrate physiology concepts (e.g. growing the rosette-dwarf mutant and applying gibberilic acid to demonstrate how treatment can compensate for the mutation) or introduce how environment affects gene expression (e.g. comparing relative purpleness in purple stem seedlings that are grown under different light intensities).
There are many options--these are just a few of the types of options that we're hoping to support teachers to explore more effectively with our new website: www.fastplants.org And as always, we hope you will post here on our Social Network, too.
If you are just trying out Fast Plants for the very first time, I recommend a visit to our "Getting Started" page.
You'll also find we have materials available for free in our digital library from 25 years of work supported by various grants to teach with Fast Plants as a model organism. One you might be interested to see is called "Who's the Father? (just search for "who's the father" at http://fastplants.org/resources/digital_library/index.php?P=Home ).
Finally, you may find two handouts useful that we designed to accompany the Artificial Selection Investigation, and those are now in our digital library: http://www.fastplants.org/cwis/index.php?P=BrowseResources&Pare...
We hope you find our resources helpful. Please let us know if we can help with additional information and/or resources. We appreciate your feedback and input.