A Revised Medium for Rapid Growth and Bio Assays With Tobacco Tissue Cultures Lab Paper review

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University of Arkansas, Fort Smith *

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123

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Chemistry

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Jan 9, 2024

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A Revised Medium for Rapid Growth and Bio Assays With Tobacco Tissue Cultures Introduction: 1. What specific modifications were made to White's modified medium in the experiments with tobacco tissue culture? a. Answer: The experiments involved supplementing White's modified medium with kinetin and indoleacetic acid, and a significant increase in yield was observed within a three to four-week growth period upon adding an aqueous extract of tobacco leaves. 2. What was the primary factor responsible for the increase in growth observed when adding an aqueous extract of tobacco leaves to the medium? a. Answer: The increase in growth was mainly attributed to inorganic rather than organic constituents in the extract, although not entirely due to them. 3. How are inorganic salts commonly carried along with organic fractions when growth factors are isolated from plant tissues and other sources? a. Answer: Inorganic salts are frequently carried along with organic fractions when growth factors are isolated. This phenomenon occurs because growth factors are often associated with or contaminated by nutrient elements or other known constituents of the medium. 4. What motivated the development of a medium with adequate supplies of all required mineral nutrients and common organic constituents? a. Answer: The motivation was to minimize interference from nutrient elements or other known constituents that might be present in the test materials used for bioassays. The goal was to create a medium where additional amounts of these constituents would not appreciably change the growth rate or yield. 5. Can the passage provide more information about the specific composition of the developed medium with adequate supplies of mineral nutrients and common organic constituents? a. Answer: The passage mentions the goal of developing such a medium but does not provide specific details about its composition. 6. What are some characteristics of the culture media in common current use for tissue cultures, and how do they compare in terms of supporting plant growth? a. Answer: The passage briefly mentions several culture media in common use for tissue cultures, including White's nutrient solution, Gautheret's medium, Hildebrandt's media, Heller's medium, and Nitsch and Nitsch's solution. It suggests that these media have varying levels of effectiveness in supporting plant growth, but it does not provide specific comparative data or characteristics of these media.

7. What are the specific deficiencies or limitations of the common culture media mentioned in the passage? a. Answer: The passage indicates that none of the common culture media mentioned provide sufficient amounts of some essential elements for the rapid growth rates and large yields achievable with tobacco tissue culture when organic growth factors are included. However, it does not specify the exact deficiencies or limitations of each medium. 8. How do the findings related to tobacco tissue culture medium development contribute to the broader field of tissue culture and plant growth optimization? a. Answer: The findings suggest the importance of optimizing the nutrient composition of tissue culture media to maximize growth rates and yields. This information could have broader implications for improving tissue culture conditions for various plant species, but the passage does not elaborate on these broader implications. Results: 1. What were the results of the preliminary testing of the basal medium when the levels of inorganic and organic constituents were doubled and quadrupled? a. Answer: The preliminary testing showed that doubling and quadrupling the levels of inorganic or organic constituents in the basal medium led to increases in the yield of tobacco callus tissue. The effect was more pronounced with inorganic salts than with organic substances. 2. Which specific inorganic elements were most effective in improving the yield of tobacco callus tissue when their concentrations were increased separately? a. Answer: The passage mentions that when each inorganic element was increased separately to four times its level in the basal medium (4x), N and K were particularly effective in improving the yield of tobacco callus tissue. However, increasing all the salts to the 4x level had an even greater effect. 3. Did increasing the concentrations of the minor elements, except for chlorine (Cl), significantly improve the yield of tobacco callus tissue? a. Answer: The passage states that, except for chlorine (Cl), none of the minor elements showed significant improvement in yield at the 4x level compared to the 1x level. 4. Can the passage provide more details on the specific composition and concentrations of inorganic and organic constituents in the basal medium? a. Answer: The passage mentions that the basal medium was modified by doubling and quadrupling the levels of inorganic and organic constituents, but it does not provide specific details about the composition and concentrations of these constituents.

5. What is the significance of these findings in terms of optimizing the growth of tobacco callus tissue in culture? a. Answer: The findings suggest that increasing the concentrations of certain inorganic elements, particularly nitrogen (N) and potassium (K), can significantly improve the yield of tobacco callus tissue in culture. This information may be valuable for optimizing tissue culture conditions for tobacco or related plant species. 6. Are there any potential limitations or drawbacks to increasing the concentrations of inorganic elements to improve tissue culture yield? a. Answer: The passage does not discuss potential limitations or drawbacks, so additional information would be needed to address this question. 7. How do these findings relate to the broader field of tissue culture and plant growth optimization? a. Answer: The findings provide insights into the role of specific inorganic elements in enhancing tissue culture yield, which can be relevant for optimizing tissue culture conditions for various plant species. However, the passage does not elaborate on the broader implications in the field of plant tissue culture. Discussion: 1. What has been the historical use of tissue cultures in addressing plant inorganic nutrition problems, and why has it been challenging? a. Answer: Tissue cultures have been advocated as a tool for addressing plant inorganic nutrition problems but have proven challenging in practice due to various reasons, which are not specified in the passage. 2. How have tissue cultures been more purposeful in the detection and study of biologically active organic substances, both natural and synthetic? a. Answer: Tissue cultures have been more purposeful in detecting and studying biologically active organic substances because they allow for controlled experiments, but the passage does not provide specific examples or details. 3. Why is caution necessary when drawing conclusions about the biological activity of a substance based on growth responses in tissue cultures? a. Answer: The passage suggests that the biological activity of a substance can vary with dosage and depends on the environment in which it is placed. Therefore, growth responses may not be a conclusive indicator of a substance's function. 4. What is the significance of an "all-or-none" response in bioassays for growth factors? a. Answer: An "all-or-none" response is considered significant evidence of a new active agent in bioassays for growth factors, indicating that a substance has a clear and specific effect on growth.

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5. How does the medium specified in Table 6 minimize the response of tobacco tissue cultures to variations in its constituents and inorganic salts? a. Answer: The passage mentions that the medium specified in Table 6 is designed to minimize the response of tobacco tissue cultures to variations in its constituents and inorganic salts, but it doesn't provide specific details on how this is achieved. 6. What factors influenced the variability observed in total yields and morphogenetic patterns in response to a given treatment? a. Answer: The passage mentions that variability in results can be attributed to differences in environmental conditions and treatment of the stock cultures, but it doesn't provide specific examples or details. 7. How do environmental conditions, such as temperature and light, affect the growth of tissue cultures? a. Answer: The passage briefly discusses the influence of temperature and light on tissue culture growth but doesn't provide comprehensive information on how these factors impact growth. 8. What are some potential reasons for differences in nutrient requirements among tissues from different plant parts or species in tissue culture? a. Answer: The passage suggests that tissues from different plant parts or species may have varying quantitative nutrient requirements, and these requirements may change with time and conditions. However, it doesn't provide specific explanations for these variations. 9. Can the passage provide more insight into the mechanisms behind the remarkable incorporation of water from the medium into the tissue cultures? a. Answer: The passage mentions the remarkable phenomenon of water incorporation into tissue cultures but doesn't delve into the specific mechanisms responsible for this process. 10. Are there any practical implications or applications of the findings discussed in the passage, particularly regarding tissue culture techniques and plant growth? a. Answer: The passage does not provide specific practical implications or applications but rather discusses various observations and considerations related to tissue culture and plant growth. Summary: 1. What is the main finding or result presented in this passage? a. Answer: The main finding is that adding leaf extract to the modified White's nutrient medium significantly increased the yield of excised pith or callus cultures of Nicotiana tabacum, variety Wisconsin 38. 2. What specific factors contributed to the increased yield of the cultures? b. Answer: The increased yield was attributed to both inorganic constituents, particularly nitrogen (N) and potassium (K), found in the leaf extract, as well as

organic constituents that enhanced both the growth rate and final weight of the cultures. 3. Were there any substances or compounds that could substitute for the leaf extract in enhancing yield? c. Answer: Yes, the ash of the leaf extract or higher levels of N and K salts in the medium could substitute for the leaf extract in increasing yield. 4. Were there other substances tested besides leaf extract that had a similar effect on growth rate? d. Answer: Yes, gibberellic acid and Braun's supplements of purines and amino acids were tested, and they increased the growth rate, although not the final yield, of the cultures. 5. What changes were made in the revised medium (Table 6) compared to the standard modified White's nutrient medium? e. Answer: In the revised medium, each essential element was provided in sufficient quantity to ensure that additional amounts would not increase yield. Sucrose was raised to 3 percent, myo-inositol was added as a regular constituent, and Edamin was introduced as an optional constituent. 6. What is the purpose of the revised medium, and for what types of experiments or assays is it designed? f. Answer: The revised medium is designed for use in bioassays of organic growth factors. It facilitates rapid growth rate, increased response to organic growth factors, and minimal interference from inorganic and common organic nutrients. 7. What is the maximum fresh weight yield achieved under specific conditions, and what seems to be the limiting factor for growth in this context? g. Answer: Under specific conditions with the presence of plant extracts, fresh weight yields of up to 35 grams on 50 ml of medium were obtained. In this context, water appears to be the limiting factor for the growth of the tobacco tissues used. 8. Does the passage discuss any aspects of general application, limitations, or behaviors of plant tissue cultures? h. Answer: Yes, the passage mentions that aspects of general application, limitations, and behavior of plant tissue cultures are discussed, but specific details are not provided in the passage. It would be necessary to read further to obtain this information.