Fruits, Seeds and the Future

FRUITS, SEEDS AND THE FUTURE JEANETTE JOHNSON

A fruit results from the maturation of one or more flowers. The ovule producing part of the flower forms all or part of the fruit. Inside the ovary/ovaries are one or more small eggs, where the embryo sac contains the egg cell. When the female embryo sac joins with two male sperm these ovules become seeds. (Biology Online, 2005) Each fruit is made of certain acids, vitamins, fructose, proteins, starch, and cellulose. These are mixed together to form certain tastes in fruit. Fruits are not just eaten because they are nutritional, the way they look and taste play a big part in whether they are chosen to be eaten. Each fruit has a different and characteristic taste. Some fruits are sweet and some are sour. There are different amounts of compounds in different kinds of fruit. Higher fructose content will make a fruit taste sweeter, while more acids will make a fruit taste sour. When fruit ripens there is less acid but more sugar. Oranges have almost the same amount of fructose and acid so they can taste both sweet and sour. Lemons do not get sweet when they ripen because they have an excessive amount of acids. Two fruits of the same kind can taste different because there may be many varieties of that fruit. There could also be a difference in the soil quality, manure used, climate, water and the way the fruit was grown. Food acids that naturally occur in many fruits are citric acid, malic acid, and tartaric acid. Without these acids fruits may taste bland. (Food Additives, 2010) The longer the time it takes for harvesting of the fruit before it gets eaten could add to a greater loss of flavor. Plants are not able to move from one spot to another on their own. They developed a way to make sure that their seeds are taken far away from them. If seeds start to develop close to the parent plant, the young plant would not receive enough sunlight to grow. When plants are to close together they have to compete for water, light, and minerals. Fruits are used by plants as a way of scattering their seeds. They have different ways of doing this. Some fruits are covered by many tiny hooks. When the fruit gets ripe and an animal brushes up against it the hook gets caught in the animal’s fur. As the animal moves along its way the fruit gets tangled in the fur until it touches the skin of the animal. After a while the fruit starts to get irritating and the animal uses its legs and teeth to pull the fruit out and leave it on the ground. The seed can then develop well away from the parent plant. Some animals disperse seeds by burying them away from the parent plant. Sometimes they forget the fruit or seed and it begins to grow. When the carpel’s (one of the female reproductive organs on a flower) develop into fruits like berries, oranges, and grapes an animal will eat the fruit and spit out the seeds. If conditions are right the seeds will develop where the animal left them. The whole fruit may be eaten by the animal seeds and all. When this happens the seeds pass straight through the digestive tract system. They are eliminated with the rest of the waste. By the time the seeds are eliminated the animal has moved away from the parent plant and the seeds are surrounded by a supply of manure. The manure helps the seed to grow. Some fruits have thin wing- like structures attached to them. When these fruit ripen the structures break off of the plant and are carried away by the wind before falling to the ground. This moves them away from the parent plant. Water dispersal is not used by many land plants. Plants that live near water may drop their seeds in the water. If the seed can float they may travel downstream until they get stuck in the mud or soil well away from the parent plant. Humans can also disperse fruit by planting seeds. When we plant our gardens or farmers plant those large crops seeds are being dispersed. By brushing up against a plant, like animals seeds can stick to parts of our bodies and our clothing. When fruits called pods (which contain rows of seeds inside them) dry out the two sides of the pod separate so violently that the seeds are thrown far away from the parent plant. (The Open Door Web Site, 2010) Humans can interfere in the process of seed dispersal by interfering with nature whether or not they intend to. The number of wild fruit species available to us now is less (although because of commerce we are provided with fruit from all over the world). The domesticated fruits we have access to have fewer seeds or there are no seeds at all. Seedless fruit in a species that normally produces by seeds are short-lived and biologically sterile. Wheat is the leading source of vegetable protein in human food it is second to rice as the main food crop. Cultivation and the repeated harvesting and sowing of the grains have lead to the creation of domesticated strains of the wild grass. The mutant strains are what the farmer would rather have. Domesticated wheat grains are larger and the seeds remain attached to the ear by a tough rachis (main axis of a group or cluster of flowers) during harvesting. In wild strains a more fragile rachis lets the ear easily shatter and disperse seeds. By domesticating the wheat the farmers have contributed to the loss of the plants natural seed dispersal mechanisms. Also domesticated strains of wheat cannot survive in the wild. (Science Magazine, 2006) Long term storage takes place in the reserve organs during one phase of a plants growth. Endosperm is the nutritive tissue in seeds of most flowering plants. Endosperm cells have three sets of chromosomes. They contain food reserves such as starch, fat and protein that are used by the developing seedling. The sugars in the endosperm of a developing seed have many potential roles, including the supply of carbon to the developing embryo and controlling gene expression in it. (Plant Physiology, 2003) To a botanist any product derived from an ovary and other flower parts is a fruit. (S. S. Mader, 2009) We have become dependent on fruit as a source of food whether it is sweet or sour. To continue the cycle of life a fruits seeds have to be moved as far away from the parent plant as possible. By domesticating fruit there may one day be no seeds to disperse. We need to be aware of the fact that by genetically engineering fruit problems can come about that can cause damage to traditional seed resources. We also should make sure that genetically altered fruits are not going to be a health risk.

References
BIOLOGY ONLINE, (2005) FRUITS FLOWERS AND SEEDS http://www.biology-online.org FOOD ADDITIVES, (2010) FOOD ACIDS http://www.foodadditivesworld.com MADER S. S., (2010) ESSENTIALS OF BIOLOGY: FRUIT TYPES AND SEED DISPERSAL (p 371)
PLANT PHYSIOLOGY: METABOLISM OF SUGARS IN THE ENDOSPERM OF DEVELOPING OILSEED RAPE (2003, VOL. 131 pages 228-236) www.plantphysiol.org SCIENCE MAGAZINE: HOW FAST WAS WHEAT DOMESTICATED (2006, VOL. 311, NO. 5769 p 1886) www.sciencemag.org THE OPEN DOOR WEB SITE (2010) FUITS AND SEEDS
www.saburchill.com/chapters/chap0045.html

References: BIOLOGY ONLINE, (2005) FRUITS FLOWERS AND SEEDS http://www.biology-online.org FOOD ADDITIVES, (2010) FOOD ACIDS http://www.foodadditivesworld.com MADER S. S., (2010) ESSENTIALS OF BIOLOGY: FRUIT TYPES AND SEED DISPERSAL (p 371) PLANT PHYSIOLOGY: METABOLISM OF SUGARS IN THE ENDOSPERM OF DEVELOPING OILSEED RAPE (2003, VOL www.plantphysiol.org SCIENCE MAGAZINE: HOW FAST WAS WHEAT DOMESTICATED (2006, VOL www.sciencemag.org THE OPEN DOOR WEB SITE (2010) FUITS AND SEEDS