Mendel Genetics Using Brassica Rapa - Research Paper Example

? Mendel Genetics Using Brassica Rapa Section TA Through the of this dis the first and second lawsof genetics, as established by Gregor Mendel, will be examined using the Brassice rapa as the instrument of experimentation. Using the scientific method, an experiment will be conducted to determine the answer to the research question: What is the inheritance pattern of the purple stem trait? Through the experiment, the hypothesis that the presence of purple pigment is dominant and the trait follows Mendelian laws will be tested. Through analysis of the experimental data collected revealing the dominance of the purple stem trait and a literature review of qualitative and quantitative data, the result will be analyzed to determine if the hypothesized prediction that the phenotypical ratio of 3:1 is established, in accordance with the Mendelian laws. Chi-square statistical analyses will be performed to determine the correspondence of the data with Mandelian ratios according to the formula X2 = ? (Observed value – Expected value) (1) Expected Value Mendel Genetics Using Brassica Rapa Introduction Scientist Gregor Mendel was the author of numerous genetic theories that explained the laws of genetic variations adopted from the findings of his numerous experiments with pea plants using the scientific method (2). The determination of the genetic dominance of specific traits in horticultural and other settings has significant impact on the biological growth of all organisms (3). The diverse groups of Brassica plants are very valuable due to their use in the production of various products and the wide array of nutritious vegetables included in this classification of plant (4). Understanding the dynamics of the role of nutrients such as actin in the pollination process and how this affects hydration and germination will assist in better cultivation of this important crop (5). Using observation as the experimental method, this discourse will answer the research question: What is the inheritance pattern of the purple stem trait? Through the experiment, the hypothesis that the presence of purple pigment is dominant and the trait follows Mendelian laws will be tested to determine the accuracy of the prediction that the purple stem is the dominant trait and the F2 generation will demonstrate phenotypical results congruent with Mandelian traits. Materials and Method To conduct this experiment, heterozygous P Brassica rapa seeds were planted on day one and cultivated in 28 by 55 centimeter plastic pots in an artificial soil compound of an equal mixture of peat moss and vermiculite and watered with distilled water on regular intervals (6). The plants were grown at a controlled temperature of 32?C under regular illumination from fluorescent lamps (7). The seeds, potting soil, and planters were the materials used for this portion of the experiment. The genotype of the parent plants used was F1, Non-Purple Stem, and Hairless. One parental plant was true breeding and green and the other parental plant was true breeding and purple. Once the seedlings began to sprout on the fourth or fifth day, the numbers of purple and green stem phenotype was recorded. The plants began to flower between days nine and eleven and were cross pollinated on day fourteen. Seed pods began to appear on day twenty-one, at which point they will be collected and germinated in the same manner as the parent plants. The number of purple and green stem phenotypes will be counted among the F1 generation to ascertain whether they follow the Mandelian principles. The seeds will appear above ground and will be collected, allocated, and counted according to the number of total seeds that germinate and the stem color of the seeds that germinate. Results Figure 1 Section 001 Table # 1 # Germinated Seeds Purple Phenotypes Green Phenotypes 1 63 51 10 2 99 78 5 3 90 74 5 4 80 56 16 5 74 58 3 6 39 25 10 Total 445 342 49 Figure 2 Section 002 Table # 2 # Germinated Seeds Purple Phenotypes Green Phenotypes 1 172 140 28 2 80 55 13 3 174 145 27 4 112 90 19 5 170 128 41 6 72 56 16 Total 780 614 144 Figure 3 Section 003 Table # # Germinated Seeds Purple Phenotypes Green Phenotypes 1 135 104 28 3 120 97 23 4 154 123 29 Total 409 324 80 Figure 4 Aggregated Data # Germinated Seeds Purple Phenotypes Green Phenotypes Section 001 445 342 49 Section 002 780 614 144 Section 003 409 324 80 Total 1634 1280 273 Three experimental sections were cultivated to ensure the aggregate data collected would be accurate even in the instance that a crop failed to germinate or produce seedlings. Six plants of the purple phenotype and six plants of the green phenotype were cultivated in both sections 001 and 002 (see Figures 1 and 2) and four plants of the purple phenotype and four plants of the green phenotype were cultivated in section 003 (see Figure 3). The aggregate data (see Figure 4) was collected and categorized according to how many seeds from each plant germinated and their stem color. Figure 5- Chi-square Observed Values Expected Values Section 001: 342/445 seeds purple phenotype (3/4)(445)= 333.75 seeds purple phenotype Section 001: 49/445 seeds green phenotype (1/4)(445)= 111.25 seeds green phenotype Section 002: 614/780 seed purple phenotype (3/4)(780)= 585 seeds purple phenotype Section 002: 144/780 seeds green phenotype (1/4)(780)= 195 seeds green phenotype Section 003: 324/409 seeds purple phenotype (3/4)(409)= 306.75 seeds purple phenotype Section 003: 80/409 seeds green phenotype (1/4)(409)= 102.25 seeds green phenotype Total seeds: 1280/1634 purple phenotype (3/4)(1634)= 1225.5 seeds purple phenotype Total seeds: 273/1634 green phenotype (1/4)(1634)= 408.5 seeds green phenotype Using the equation X2 = ? (Observed value – Expected value) Expected Value, the data is analyzed to determine if the results of the experiment adhere to the Mandelian principles and yield a ratio of 3:1, where there are three times as many purple stemmed plants as there are green stemmed plants. The Degree of Freedom (df) = n-1, where n = the number of classifications of seeds within the experiment, therefore, n=2. Purple seeds: X2 = (342-333.75) 2 + (614-585) 2 + (324-306.75) 2 333.75 585 306.75 .204 + 1.437 + .9700 = 2.611 n = 2, df = n-1, df = 1 X2 = (1280-1225.5) 2 =2.424 1225.5 Green seeds: X2 * ? (49-111.25) 2 + (144-195) 2 + (80-102.25) 2 111.25 195 102.25 34.83 + 13.34 + 4.84 = 53.01 n = 2, df = n-1, df = 1 X2 = (273-408.5) 2 = 44.95 408.5 Since the resultant value is greater than n, we can accept the given hypothesis that the presence of purple pigment, anthocyanin, is the dominant trait in the experimental plants Brassica rapa. Conclusion, Analysis, Discussion The experiment performed used the fast-growing plant, Brassica rapa to attempt to answer the research question: What is the inheritance pattern of the purple stem trait? Through the experiment, the hypothesis that the presence of purple pigment anthocyanin is dominant and the trait follows Mendelian laws was verified, as exemplified by the presented results. We can also conclude that the phenotypic results for the experiment are concurrent with the standards established by Mendel, depicting a close approximation of the 3:1 ratio. Although the hypothesis does not fully depict an exact replica of a perfect 3:1 ratio, the X2 value being greater than the value of n sets the determination that the purple stem variation is the dominant trait for the plant. Analysis of this particular species of plant is highly valuable to the human food chain since this plant includes such a wide variety of crops. Foods such as cabbage, cauliflower, broccoli, kale, turnips, pak choy, brussel sprouts, mustard greens, collard greens, and a wide variety of vegetables are derived from this species of plant (8). Valuable oils, such as rapeseed oil, are also a derivative of the Brassiceae family of plants and are a highly valuable commodity (9). Analysis of the genetic structure of the plant is useful for indications on which species can be cross cultivated to produce more resilient plants that will live beyond their annual life cycle and have the ability to be cultivated in a wider variety of terrains (10). Comprehension of the specific genetic attributes of the species will help determine what alleles are transmitted from parent to offspring to produce the desired results (11). Additionally, this will allow for manipulation of the plant to garner desired results. The small amount of current genetic data on brassicas has made the analysis on rapid-cycling varieties highly useful to gaining an understanding of this highly valuable plant species (12). The naturally occurring variation of this strain that flowers faster than other types of brassicas was bred under controlled circumstances for the specific purpose of studying the family of plants as a whole to instigate development of a higher knowledge of the genetic structure of the plant (13). This research has led to the development of rapid-cycling brassica plants for use in applied biology for the study of the cultivation of specific traits (14). The development of cross-bred strains and other variations are also under investigation (15). These plants are also widely used in educational forums to provide educators with fast-growing, living material to use in their lessons (16). Although none were performed in this experiment, a test cross analysis can be done to establish the genotypes of the offspring plants and whether they are heterozygous or homozygous (17). Even though the purple stemmed plants appear to be the dominant trait, Mendel’s law of segregation determines that each parent can only pass one allele to their offspring (18). This presents the question of whether the green stem is a recessive trait as a result of incomplete dominance, co-dominance, or whether the plant is polymorphic (19). Additional investigations can be compiled using variations of the brassiceae plant to establish the heartiest strains for cultivation. The computational anomalies noted in this study can be attributed to numerous contributory factors. The lack of germination of the some of the seeds in the second generation could have had an effect on the outcome of this study. Additionally, possible anomalous variations in the stem color of the cross-bred plants in the second generation may have necessitated their elimination from the study, which could have also significantly affected the number of plants in the study, causing the ratio to be different than that which was anticipated prior to experimentation. These unanticipated results are grounds for additional research and experimentation in this field to solidify the results and gain a definitive answer to the research question: What is the inheritance pattern of the purple stem trait? Also, the determination as to whether the hypothesis that the presence of purple pigment is dominant and the trait follows Mendelian laws requires a definitive analysis in order to make a solid presumption on either accord. The undeniable value of this plant as a cultivatable crop that can supply an abundant food source to human and animal populations makes investigation into the potential of the species a viable topic. Cited References 1) McClean, P. Mendelian Genetics. [Internet]. 2000 [cited 2011 July 28]. Available from http://www.ndsu.edu/pubweb/~mcclean/plsc431/mendel/mendel1.htm 2) McClean, P. Mendelian Genetics. [Internet]. 2000 [cited 2011 July 28]. Available from http://www.ndsu.edu/pubweb/~mcclean/plsc431/mendel/mendel1.htm 3) Williams, PH, Hill, CB. Rapid-cycling populations of Brassica. Science New Series 1986 [cited July 28, 2011], 232(4756): 1385-1389 4) Regulatory Directive. The biology of Brassica rapa L. Government of Canada Canadian Food Inspection Agency [Internet]. 1999 [cited July 28, 2011]. Available from http://www.maltawildplants.com/CRUC/Docs/BRSRA/BrassicaRapa.pdf 5) Iwano, M., Hiroshi, S., Matoba, K., Miwa, T., Funato, M., Entani, T., Nakayama, P., Shimosato, H., Takaoka, A Isogai, A, Takayama, S. Actin dynamics in papilla cells of Brassica rapa during self- and cross-pollination. Plant Phisiology [Internet]. 2007, 144: 72-81 [cited July 28, 2011]. Available from www.plantphysiol.org 6) Williams, PH, Hill, CB. Rapid-cycling populations of Brassica. Science New Series 1986 [cited July 28, 2011], 232(4756): 1385-1389 7) Williams, PH, Hill, CB. Rapid-cycling populations of Brassica. Science New Series 1986 [cited July 28, 2011], 232(4756): 1385-1389 8) Williams, PH, Hill, CB. Rapid-cycling populations of Brassica. Science New Series 1986 [cited July 28, 2011], 232(4756): 1385-1389 9) Mun et al. Sequence and structure of Brassica rapa chromosome A3. Genome Biology 2010 [Internet], 11: 1-12 [cited July 28, 2011]. Available from http://www.genomebiology.com/2010/11/R94 10) Mishler, BD. Lecture outline: Evolution lecture #10 -Mendelian genetics, Hardy-Weinberg. Berkley [Internet]. 2006, October 23 [cited 2011 July 28]. Available from http://ib.berkeley.edu/courses/bio1b/evolutionfall06/pdfs/Mishler10_Mendel.pdf 11) Mishler, BD. Lecture outline: Evolution lecture #10 -Mendelian genetics, Hardy-Weinberg. Berkley [Internet]. 2006, October 23 [cited 2011 July 28]. Available from http://ib.berkeley.edu/courses/bio1b/evolutionfall06/pdfs/Mishler10_Mendel.pdf 12) Stephenson, P., Baker, D., Girin, T., Perez, A., Amoah, S., King, GJ, Ostergaard, L. A rich TILLING resource for studying gene function in Brassica rapa. BMC Plant Biology 2010 [Internet], 10(62): 1-10 [cited July 28, 2011]. Available from http://www.biomedcentral.com/1471-2229/10/62 13) Williams, PH, Hill, CB. Rapid-cycling populations of Brassica. Science New Series 1986, 232(4756): 1385-1389 14) Williams, PH, Hill, CB. Rapid-cycling populations of Brassica. Science New Series 1986, 232(4756): 1385-1389 15) Williams, PH, Hill, CB. Rapid-cycling populations of Brassica. Science New Series 1986, 232(4756): 1385-1389 16) Williams, PH, Hill, CB. Rapid-cycling populations of Brassica. Science New Series 1986, 232(4756): 1385-1389 17) Mishler, BD. Lecture outline: Evolution lecture #10 -Mendelian genetics, Hardy-Weinberg. Berkley [Internet]. 2006, October 23 [cited 2011 July 28]. Available from http://ib.berkeley.edu/courses/bio1b/evolutionfall06/pdfs/Mishler10_Mendel.pdf 18) Mishler, BD. Lecture outline: Evolution lecture #10 -Mendelian genetics, Hardy-Weinberg. Berkley [Internet]. 2006, October 23 [cited 2011 July 28]. Available from http://ib.berkeley.edu/courses/bio1b/evolutionfall06/pdfs/Mishler10_Mendel.pdf 19) Mishler, BD. Lecture outline: Evolution lecture #10 -Mendelian genetics, Hardy-Weinberg. Berkley [Internet]. 2006, October 23 [cited 2011 July 28]. Available from http://ib.berkeley.edu/courses/bio1b/evolutionfall06/pdfs/Mishler10_Mendel.pdf 20) Read More