The world human growth population is currently estimated to be 6,877,677,221 according to United States Census Bureau and is expected to grow geometrically in some more years. This growth will give impact on providing enough food supplies while maintaining the integrity of our ecosystem. Pimentel, Huang and Cordova state that this problem is reported from Food and Agricultural Organization of the United Nations, other international organizations, and scientific research. Therefore, scientists have done many research and modifications on features of plants to make them suitable as crop plants in order to overcome this problem.
The first features of crop plants that have been improved can be seen through their seedless fruit. Seedless fruit can be obtained via mutation breeding. In this case, grape will be the example. First, the fruit is allowed to develop normally while aborting the seed. This makes the seedless grape to enlarge smaller than seeded grape because the seed basically produces plant auxin hormone which enlarging the fruit. This problem is settled when the seedless grape is sprayed with gibberellic acid later and this allow them to reach its normal size before selling it to the market (Hershey,2001).Suprisingly, people gave a good response to the seedless grape and asking to continue this since the seeded one is hardly to digest. Hence, the researchers choose to improve the seedless fruit continually since it got higher potential marketing compared to seeded one.
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Higher nutritional content in crops will be the second features of crop plants that have been improved. The increased nutritional content in crops is chosen because it enables people to obtain sufficient vitamins and avoid symptoms of vitamins deficiency. Hence, genetic engineering is used to increase amount of nutrient contents like vitamins in food crops. This is done to Golden Rice. Golden Rice is a white rice crop that has the modified vitamin A. A compound called geranylgeranyldiphophate, which is an early intermediate in the pathway for vitamin A production is synthesized by the rice endosperm. In this case, Al-Babili, Hoa & Schaub state that '' phytoene synthase (psy) and Î²-cyclase genes from the daffodil plant(Narcissus pseudonarcissus) and the phytoene desaturase (CrtI) gene from the bacterium Erwinia uredovora'' are considered to increase the amount of vitamin A. Then, the genetically modified rice producing pro-vitamin A is crossed with another line containing high levels of available iron. The high pro-vitamin A/ high available iron hydbrid is called Golden Rice. However, this nutritional value cannot be seen and it is referred from The Ministry of Health Malaysia resources.
The third features that have been modified are crop disease resistance. Crop disease resistance is linked with genetic manipulation. In this case, the gene is manipulated using pathogen control. The pathogen mutates continually to overcome this resistance. For instance, the transgenic transformed tobacco contains chitinase gene coded from the bacterium S. Marcescens for pathogenesis-related (PR) proteins to combat the fungal pathogen. There is a synergistic effect where both intracellular and extracellular forms of the enzyme (glycosylated or unglycosylated forms) will give the plants increase their tolerance to the pathogen Rhizoctonia solani. The gene provided increased protection against the soil-borne fungal pathogen R. Solani when glucanases, which also PR proteins expressed in the transgenic tobacco under control of 35S promoter (Slater, Scott &Fowler, 2008).The reason for choosing this crop disease resistance is minimizing yield loss caused by fungal pathogen attack. Therefore, it can be concluded that this improvement gives profits to the farmers.
The last improved features in crop plants discussed are the size of fruit. There are many ways to increase the fruit size in crop plants. Here, domestication is stressed to increase fruit size plants. One of the extreme cases that experience domestication is the evolution of tomato fruit size. The putative ancestor of cultivated tomato (Lycopersicon esculentum cv Cerasiforme) size before is smaller than the modern tomato. This is because modern tomato has many locules compared to putative wild ancestor of cultivated tomato and may weigh up to 1 kg (Cong, Barrero& Tanksley,2008). According to Frary et al, one quantitative trait locus (QTL), fw2.2 in tomato is important for a large step in this process. In order to reduce the fruit size, it had ''gene action expected for fw2.2 and predicted amount of cosmid that is derived from fw2.2 region of a small-fruited wild species''. Under domestication, this will help altering tomato into larger-fruit cultivars process later. Another way to adjust the fruit size is via selective breeding. The good example is larger size of endocarp in palm oil. This can be obtained by cross breeding between the wild oil groves of West Africa that consist thick mesocarp called Dura with
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Psifera which is the thin shell. This hybrid results to a larger endocarp with much thicker mesocarp and thinner shell. Therefore, it can be concluded that the fruit size can be modified through various method listed above.
As a conclusion, there are many features of the plants that have been improved to make it suitable as crop plants. These modified features include seedless fruit, high nutritional yield content, crop resistance disease and size of fruit. The observations show that these modified features give a good impact to crop industry. However, this modified features disrupted some natural variation in plants. Besides, there is doubt about the safety of eating this modified crop since we do not know the side effects. Hence, modified features of crop plants have pro and cons. It depends to us to judge it.
World POPClock Projection. (2010). Retrieved November 1, 2010 from http://www.census.gov/ipc/www/popclockworld.html
Pimentel, D., Huang, X., Cordova, A., & Pimentel, M. (1996).Impact of Population Growth on Food Supplies and Environment. Retrieved November 1, 2010 from http://dieoff.org/page57.htm
Hershey, D. (2001). How are seedless grapes produced? Retrieved November 1,2010 from http://www.madsci.org/posts/archives/may2001/990303448.Bt.r.html
Al-Babili, S., Hoa, T.T.C., & Schaub, P.(2005).Exploring the potential of the bacterial carotene desaturase CrtI to increase the Î²-carotene content in Golden Rice[Electronic version].Journal of Experimental Botany, 57(4), 1007-1014.Retrieved November 1,2010 from http://jxb.oxfordjournals.org/content/57/4/1007.full
Slater, A., Scott, N.W., Fowler, M.R.(2008).Plant Biotechnology the genetic manipulation of plants (2nd ed.).New York: Oxford University Press Inc.
Cong, B., Barrero, L.S., & Tanksley, S.D.(2008). Regulatory change in YABBY-like transcription factor led to evolution of extreme fruit size during tomato domestication. Retrieved November 1,2010 from http://webcache.googleusercontent.com/search?q=cache:8uItMuuZ22MJ:en.dogeno.us/2008/06/a-transcription-factor-regulates-tomato-fruit-size-during-domestication/+domestication+of+large+tomato+size+methods&cd=8&hl=en&ct=clnk&gl=my
Food and Agriculture Organization of the United Nations.(2002).Small-scale palm oil processing in Africa Volume 148 of FAO agricultural services bulletin. Retrieved November 1,2010 from http://books.google.com.my/books?id=cET5PdWGbIQC&pg=PA3&lpg=PA3&dq=large+oil+endocarp+process&source=bl&ots=ya1G_fxUtj&sig=POsVMvRsak0FiE3kXKBR6MOyWzM&hl=en&ei=84DPTN2HLIqkvgPq-4XsBQ&sa=X&oi=book_result&ct=result&resnum=4&ved=0CCEQ6AEwAw#v=onepage&q&f=false