PlSc 300 Plant Propagation. Final Exam (150 points) Spring 2010

Transcription

1 1 PlSc 300 Plant Propagation Final Exam (150 points) Spring 2010 Directions: You have two hours to complete this exam. Try to answer the following questions to the best of your ability. If you have any questions, please raise your hand. Be sure to write your number on each page. Good luck! A. True/False: Circle T if the statement is true. Otherwise, circle F if the statement is false. (20 points; 1 point each) 1. T F Stomata on leaves of tissue culture plantlets are often non-functional and remain open during the acclimatization process (Stage IV). 2. T F Plant tissue cultures can go dormant if red and blue light are used during micropropagation. 3. T F Accumulation of oxygen should be prevented in tissue culture vessels that contain shoot cultures. 4. T F Microorganisms growing in plant tissues used for explants often cause little harm to the explant tissue but may contaminate the cultures. 5. T F Tissue proliferation of shoot cultures during micropropagation is caused by internal microbial contamination of the shoots. 6. T F A chimera is a plant with two or more genetically different tissues growing next to each other. 7. T F Shoot-tip dieback on microshoots is caused by a low nitrate to ammonium ratio in the culture medium. 8. T F Topophysis seen on asexually propagated plants could be caused by an epigenetic change. 9. T F The scutellum forms between the two cotyledons in developing dicot seeds. 10. T F Apomixis can lead to producing clonal rootstocks from seeds. 11. T F The coleorhiza helps the shoot emerge from a monocot seed. 12. T F Seed coverings, including the seed coat, can prevent vivipary.

2 2 13. T F Parthenocarpic fruit can be used as a source of apomictic seeds. 14. T F Photodormancy and after-ripening of seeds are types of non-deep physiological dormancy. 15. T F An accumulation of gibberellin in the cotyledons is known to induce endogenous, physiological deep dormancy of seeds. 16. T F Secondary dormancy of seeds is induced by improper environmental conditions. 17. T F Cytokinins promote cell expansion and root formation, whereas auxins promote cellular differentiation in plants. 18. T F After a tissue is formed on a woody plant, it usually retains its developmental (ontogenetic) age for the life of the plant. 19. T F A runner and a stolon are essentially the same type of specialized structure. 20. T F Identical plant tissue culture techniques are used to form embryos from vegetative cells and microspores. B. List answers to the following questions: Be sure to keep your answers short - these are not essay questions. (14 points; 2 points for each answer) 1. List four ways to overcome hyperhydricity of plant tissue cultures. 2. List three types of exogenous dormancy of seeds.

3 3 C. Drawing: Draw the following items (4 points) 1. Draw an endospermic seed. Label any parts to show you know the correct type of seed. D. Matching: Place the number from the group at the right on the line(s) by the descriptions at the left. Answers may be used more than once or not at all. Some questions may even have two or more answers that fit the description. WRITE ONLY ONE ANSWER, however. (24 points; 2 point each) 1. For this section, match the explanation on the right with the term on the left. 1. expression of different genes causing phenotype changes for an organism 2. tissue cultures no longer needing an exogenously supplied growth regulator 3. a type of genetically active vivipary a. epigenetic 4. wet or glassy appearance of tissue cultures b. polyploidy 5. change in DNA sequence in a species c. topophysis 6. multiplication of an entire set of chromosomes d. shoot-tip dieback 7. causes roots to form from the L I and L II layers of a vegetatively propagated plant e. hyperhydricity 8. caused by calcium deficiencies in the plant f. habituation tissue 9. change in growth habit caused by location of a branch used for a stem cutting 10. addition of one or several chromosomes 11. subtraction of one or several chromosomes 12. gall-like growth on microshoots or plants propagated by axillary shoot cultures

4 4 2. For this section, match the explanation on the right with the term on the left. 1. another name for apomixis 2. modified cotyledon in seeds a. morphological dormancy 3. can be an exo-endodormancy b. vivipary 4. also referred to as an epicotyl dormancy c. thermodormancy 5. can be overcome by warm stratification d. histodifferentiation 6. a type of nondeep physiological dormancy e. parthenocarpy 7. can be prevented by fruit pulp or juice f. combinational dormancy 8. dormancy relieved by cold stratification 9. fruit development without seeds 10. dormancy that causes seeds to become dormant again rather than germinate 11. development of an embryo in the seed **************************************************************************************************** E. One-sentence answers: The following questions can be answered with one or two sentences. Longer answers are acceptable, but try to keep your answers concise. (80 points; 5 points each) 1. How can Stage IV plantlets be protected from pathogens during the acclimatization process? Explain one way to protect plantlets. 2. What is a general temperature range and photoperiod used during micropropagation and tissue culture of plants?

5 5 3. Why is determining the tissue layer or layers that is/are responsible for leaf variegation difficult to determine for angiosperm dicot plants? Briefly explain your answer. 4. Why is a bud-sport considered a chimera? 5. What is aneuploidy? Please define this term. 6. What are two potential causes of transient increased vigor of plants produced by tissue culture? NOTE: mention two causes other than epigenetic changes. 7. Name one important difference between monocot and dicot seeds as their embryos form during seed formation. 8. Briefly describe two ways to obtain seedless fruits.

6 6 9. What is an endogenous physiological intermediate dormancy? Define this type of dormancy. 10. What is photodormancy, and what wavelengths of light are involved with this type of dormancy? 11. List the five categories of plant growth regulators and briefly write what you think is the most important role of each for plant propagation. 12. On a large tree that is difficult to propagate by stem cuttings, where (name one location) should stem material be taken to make cuttings to give the best chance for successful rooting? Why? Explain your answer. 13. Compare and contrast a tuber and a rhizome. 14. Why is callus culture avoided when trying to reproduce plants via tissue culture in commercial nurseries? Briefly explain your answer.

7 7 F. Thought Provokers: Think carefully about the facts presented in each situation before trying to answer the problem. The answer to each question will probably take only five or six sentences, so be as concise as possible. Don't attempt to "gab" your way through the answers (18 points; 9 points each) 1. The diagram to the right shows the cross section of a plant stem with normal and mutated tissues. To the right of the stem cross section is a longitudinal section (lengthwise cut) of a stem that developed from a bud formed at the intersection of the two tissues. To the right of the longitudinal section is a cross section of the stem from the new bud. What type of chimera is shown here (see the arrows)? Provide a specific name. Assuming this is an angiosperm dicot plant, in what layer(s) did the chimera originate? How stable is this type of chimera? Explain your answer Chimera of interest

8 8 2. After graduation, you are hired by a school board to teach vocational agriculture and horticulture courses. Part of the curriculum involves propagating plants from seeds. You are given Chinese juniper, Juniperus chinensis, seeds to use for propagating. You have no idea if the seeds are dormant or can germinate immediately, so you sow some of the seeds. The seeds fail to germinate, so you check reference book and find that the seeds need about 120 days (4 months) of cold treatment to break dormancy. What type of dormancy do these seeds have? Write out the specific FULL name of the type of dormancy. What leads you to this conclusion? How do you need to treat the seeds to break dormancy? Please name the treatment needed and list the requirements needed to complete this treatment.