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| C-Fern™: A Dynamic Approach to Plant Biology | ||||||
| Leslie G. Hickok, PhD and Thomas R. Warne, PhD | ||||||
| From the Department of Botany | ||||||
| University of Tennessee, Knoxville, TN 37996 | ||||||
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plants alive? Do they do anything interesting? Ask these questions to any number of high
school or college students and be prepared for a variety of answers! Even biology majors
may give surprising responses. Teaching the basics of plant biology and capturing
students' interest can be a daunting task. Nonetheless, plants are an integral and
essential part of our living world, and learning about them is a necessary component of
any liberal or specialized education; thus finding better ways to teach about plants is a
challenge. A Model Approach Using model plant systems can be an effective way to develop compelling exercises and experiences for students. But for an organism to be useful in teaching plant biology, it must be interesting, simple to learn about and use, easy to grow and manipulate, and applicable to a broad range of disciplines and educational levels. C-Fern™, a specially derived cultivar of the tropical homosporous fern, Ceratopteris richardii, has all of these features and offers a dynamic new approach to teaching the basic aspects of plant biology.
A principal feature of C-Fern is the rapid development of gametophytes over 2 to 3 weeks. Under optimum conditions, spores (Fig. 1) germinate 3 to 4 days from starting (DFS) the culture and develop to maturity by 10 to 12 DFS. The presence of 2 distinct sexes, males and hermaphrodites (Fig. 2), provides yet another interesting feature. Control of sexual differentiation depends on a chemical signal or pheromone. In the absence of the signal, early germinating gametophytes develop into hermaphrodites that synthesize and secrete the pheromone.
This then affects later germinating gametophytes that develop into males. The presence of males with many sperm-containing antheridia (Fig. 3) allows students to visualize directly hundreds of swimming sperm that are released when water is added to the culture. Sperm are chemotactically attracted to eggs and form large frenetic swarms around mature archegonia on hermaphroditic gametophytes.
Students can view all phases of gametophyte growth and differentiation, fertilization, and early embryo development (Fig. 4) using a stereomicroscope and/or compound microscope. This demonstration of sex by a plant showing distinctive sexual types and actively swimming sperm that seek out and fertilize receptive eggs fascinates students. It provides a dynamic exposure to basic aspects of gametophyte development, sexual differentiation, pheromonal/chemical control of development, and plant sexual reproduction and alternation of generations.
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