Rice Plant Disease Resistant To Blight example essay topic

Rice is the main food for about one-third to one-half of the world's population. A mature rice plant is usually two to six feet tall. In the beginning, one shoot appears. It is followed by one, two, or more offshoots developing. There are at least five or six hollow joints for each stalk, and a leaf for each joint. The leaf of the rice plant is long, pointed, flat, and stiff.

The highest join of the rice plant is called the panicle. The rice grains develop from the panicles. (Jodon, 300) Rice is classified in the grass family Gramineae. Its genus is Oryza and species O. sativa. It is commonly cultivated for food in Asia.

Some varieties of rice include red rice, glutinous rice, and wild rice. (Jodon, 303) The kernel within the grain contains most of the vitamins and minerals (298). The kernel contains thiamine, niacin, and riboflavin (299). Rice has many enemies that destroy a majority of the rice crops.

The larvae of moth, stem borers, live in the stems of the rice plants. Some insects suck the plant juices or chew the leaves. Birds, such as bobolink, Java sparrow, or paddy bird, would eat the seeds or grains. Disease causing factors such as fungi, roundworms, viruses, and bacteria also destroy the rice plants.

Blast disease is caused by fungi which causes the panicles containing the grains to break. (Jodon, 300) There are various types of rice grown all over the world. A majority of rice grown is cultivated rice. When rice is grown with water standing on the fields, it is called lowland, wet, or irrigated rice. Rice plants grown in certain parts of Asia, South America, and Africa are called upland, hill, or dry rice because they are raised on elevated lands that cannot be flooded, but with plentiful rainfall. Wild rice is grown along lake shores of Canada and the Great Lakes.

It is usually eaten by people in India. Scented rice is the most expensive because is has long grains and tastes like popcorn when cooked Glutinous rice is waxy rice consumed by Asians. It is cooked to a sticky paste and is used for cakes and confections. (Jodon, 299) Rice was thought to have originated in southeast Asia when Alexander the Great invaded India in 326 B. C (Jodon, 303). Further research revealed that rice was cultivated around or at the Yangtze River in China, around 4000 to 11,500 years ago.

One archaeologist, Toyama, surveyed data on 125 samples of rice grains, plant remains, husks, and other factors from numerous sites along the length of the Yangtze River. "He reported that the oldest samples... are clustered along the middle Yangtze in Hubei and Hunan provinces. Samples from the upper and lower portions of the Yangtze River were found to be younger, around 4,000 to 10,000 years old. "This pattern... suggests that rice cultivation originated in the middle Yangtze and spread from there". Archaeologists see more than a decade of excavation of the Yangtze River and nearby sites to confirm that the Yangtze River is where rice was first cultivated. (Normille, 309) The Greeks learned of rice when Alexander the Great invaded India around 326 B.C. Spain was introduced to rice when it was conquered by the Moors during the 700's A.D. Spain then introduced rice to Italy, around the 1400's.

The Spanish also introduced rice to the West Indies and South America, around the 1600's. Rice was introduced to the United States when a Madagascar ship docked in the Charleston, South Carolina harbor. The ship captain presented the governor with a sack of seed rice. It was then grown in states south of the Ohio River and east of Mississippi. (Jodon, 303) Rice is usually grown in lowland fields divided by dirt walls (Jodon, 300) A majority of the rice crops are grown with water standing on the fields (Jodon, 299). On level land, these paddies and dirt walls are built in wavy or straight lines.

On hill-like land, they follow the slopes and form paddies that rise like steps. The dirt walls are used to hold in water for the fields. (300) Cultivation of the rice plant requires controlling the water supply and weeding the rice fields. Water must be two to six inches deep for the seeds to germinate properly. After the grains germinate, the water is drained.

The rice plant is then cultivated by hand. (Jodon, 301) Besides steaming the rice for consumption, it is also used for other products. Enriched rice is regular kernels and vitamin and mineral coated kernels mixed together. The Japanese use the fermented rice kernels to make sake, rice wine. Rice is sometimes used in making beer in the United States and Europe. Powdery by-products, bran and polish, are used to feed livestock.

Starch from the rice plant is used in laundry starch. The Japanese usually use the rice hulls to prevent breakage of fragile objects during shipping. Rice hulls also serve as fuel for steam engines. The dried stalks of rice are used to make sandals, hats, raincoats, and thatching roofs.

In the Philippines, farmers grow mushrooms on beds of rice straw. (Jodon, 298-99) The purpose of the "Super Rice challenge" is to create rice plants that are disease resistant, insect resistant, and produces twenty-five percent more food per acre. The International Rice Research Institute has been working on this challenge. It is competing with many various factors that are pushing the International Rice Research Institute to try and complete the challenge as soon as possible. Factors such as growing population, limited areas for growing rice, and the common farmer's philosophy of "get anything to grow" are pushing researchers to complete the project as soon as possible.

Also, the new varieties of rice has raised a question of the farmer's health because of the uses and effects of agricultural chemicals. Since normal rice grown in paddies produces high amounts of methane, the International Rice Research Institute must also find a way to create rice plants with a low methane production. Gur dev K hush believes that the "super rice" will be ready for farmers to plant them around the end of the century. (Bioscience, 239) Researchers were able to develop a type of rice during the 1960's. This type of rice, called "miracle rice", because of its high yields. Researchers were able to develop it by combining a short variety of rice with a tall variety.

This crossbreeding resulting in a rice plant that can withstand wind and rain and have a high production yield. This new breed was thought to have been to reduce the food shortages that depend on rice as a staple food, but because of various conditions in other countries, this rice plant was not very successful. (Jodon, 299) Blight, caused by bacteria, spreads rapidly through rice fields in water droplets. The rice plant would develop lesions and die in a matter of days. This disease could destroy about half of a rice crop. Through genetic engineering, the author and her colleagues have been able to introduce isolated disease-resistant genes into the rice plants.

(Ronald, 100) The gene, called Xa 21, was discovered by the International Rice Research Institute, and Ronald attempted to clone Xa 21 from the International Rice Research Institute variety. (101) The Cornell group created a genetic map which showed the location of hundreds of markers on the twelve rice chromosomes. Ronald and her colleagues used this genetic map to locate gene Xa 21 by examining over one thousand rice plants to "see how often known DNA markers showed up in conjunction with resistance to blight". They used chromosomal swapping and rearranging that goes on during sexual reproduction.

The more often they saw resistance in the next generation of rice plants, the closer they were to locating the gene. (102) Since rice plants are defiant in accepting outside DNA, they used a gun that "shoots microscopic particles into intact cells", which was developed by John Sanford of Cornell. After using this procedure to introduce Xa 21 into an old, but susceptible, rice plant they exposed the plants to blight. They found that the plants were resistant to the blight. Ronald and her colleagues current goal is to introduce Xa 21 into rice varieties that are agriculturally important. (102-03) Current studies showed that rice plants introduced to the cloned Xa 21 gene have become blight resistant.

Since farmers prefer to grow plants that have adapted to the various climates and conditions, Ronald stated that "the genetically engineered versions will be identical to the original plants except for the addition of the single cloned gene... ". . Ronald and her colleagues still have to field-test the new varieties for yield, taste, and hardiness to confirm that the original adaptations have remain unchanged. (104) The success of this project has reached into testing the process and the gene on other plants. Scientists hope that Ronald's process of making the rice plant blight resistant will work on other plants.

They hope that this process will be successful on valuable crops, such as citrus crops. They plan to combine the gene Xa 21 and other disease resistance genes to enhance the plant's resistance to disease. The problem with cloning the Xa 21 gene is that it is still vulnerable to other diseases such as grassy-stunt and ragged-stunt viruses. (Ronald, 104) The purpose of Japan's rice genome project is to fully map the twelve chromosomes of the rice plant.

Low funding of this project has hindered the progression of this project. Since Japan has increased its funding to its genome project, the rice genome division can now complete mapping the twelve chromosomes of the rice plant. (Normille, 1702) Rice is one of the world's most important crops because a majority of the world depends on this as a staple food. The number of rice plants planted, however, are greater than the number of rice consumed. This is because of various factors that destroy the rice plants before they can be harvested for commercial use.

Various factors, such as insects, birds, and disease, destroy the rice crops. Projects are being conducted to improve the rice plant, but researchers encounter various obstacles. Making the rice plant disease-resistant to blight may be useful and valuable, but they must also find a way to make the rice plant resistant to other diseases and viruses such as ragged- stunt. Since Japan has increased its funds to its genome projects, they have been able to increase the work on mapping the twelve rice chromosomes. Scientists hope that these projects will be finished, and that farmers will be using the enhanced genes on their rice plants by the beginning of the next century. "The Super Rice Challenge."Bioscience".

Apr. 1995 vs. 45. pp. 239 Jodon, Nelson. "Rice". World Book Encyclopedia. 1976, Chicago. Field Enterprises Educational Corporation. vs. 16. pp. 298-303 Normille, Dennis. "Rice Genome Races Ahead."Science".

5 Dec. 1997. vs. 278. pp. 1702 Normille, Dennis. "Yangtze Seen as Earliest Rice Site."Science". 17 Jan. 1997. V. 275. pp. 309 Ronald, Pamela. "Making Rice Disease-Resistant."Scientific American".

Nov.! 997. pp. 100-105.