Plants Hold the Basic Patents Yale U n i k r s i t y , New Hauen, Connecticut
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AN you imagine a marvelous liquid pumped into the tank of your car which would not only give i t motive power but would service it, repair it, and provide themeans for transforming it into next year's model? If you can imagine this, then you will have a fair picture of what food does for your own body and for that of every living thing. These bodies are complex organic machines, and f w d is the stuff which provides the fuel t o keep them running and the material from which they are built and repaired. The problems of what food is, whence i t comes, and how it is used in the growth and activity of living things are therefore among th? most fundamental ones in biology and are particularly important in a world where millions of people still go hungry. One of the most important facts about food, but one which fails too often to berecognized, is that all f w d is made by plants. I n plants alone are produced those basic chemical compounds from which every kind of food must come. Out of the relatively simple compounds produced in plants there are then built, in the bodies of animals which eat the plants, a host of more complex substances: but these simple compounds themselves are made only by plants. Plants hold, so t o speak, the basic patents upon which not only the food supply of the world, hut also all other products of living things, are manufactured. There is solid scientific truth in the familiar remark that all flesh is grass. Notable among these patents is the one which plants use for making sugar out of water and the carbon dioxide gas of the air. This union is brought about only through the agency of the allimportant substance called chlorophyll-the pigment which makes plants green-and by the energy of light. Glucose, the simple sugar formed in this way, is the baiic material from which starch, cellulose, and the other carbohydrate substances are made. so that from green plants come most of the staple energy foods of mankind. The practice of agriculture is primarily the exploitation of this fundamental food-making ability of green plants. The process itself, which yet we are unable t o duplicate in the laboratory, is also of the utmost scientific interest and is being studied intensively by botanists. biochemists, and biophysicjsts. Another basic patent held by plants is used in the making of proteins. These substances, produced by the union of nitrogen compounds with carbohydrates, are important since they are necessary for the growth and repair of living tissues, which themselves are mostly made of proteins. Proteins are extremely complex. but they are all built from a score or so of relatively simple nitrogen-containimg substances called amino acids. Those essential for human nutrition are made only by plants: All the milk, meat, eggs, and other such protein foods which we obtain from animals have their original source in the plants which these animals eat. Many colorless plants as well as green ones can make proteins, and light is not necessary in the process. Yeasts (which are plants) have, for example, come t o be used in the last two or three years for the production of great amounts of protein from molasses, distillery wastes, and other materials. A whole new industry and source of food for men and domestic animals is thus being developed which will be of great importance in regions like the West Indies, where these materials can be produced so cheaply. Other tiny plants, the bacteria, some living free in the soil and others in the root nodules of beans, soys, and similar crops, hold a third basic patent, that for taking nitrogen directly from the immense supplies of it in the atmosphere and converting it into protein. something that higher plants cannot do since they must get their nitrogen only from compounds in the soil. This is what makes members of the legume family, which har-
bor these bacterial guests, so important t o man and the economy of nature generally; and their proteins, thus made from sugar and air, are of increasing importance in our diet. Here also is a hopeful source of other raw materials. Soys alone already yield almost everything from meat substitutes t o door knobs! I n recent years still another group of substances essential in nutrition have been found t o owe their origin t o plants-the vitamins. Vitamin A is related t o the yellow pigments associated with chlorophyll. The B vitamins, some of the names of which are now household words, cannot he made in the bodies of animals or man, hut in nature have their source entirely in plants. So does much of our supply of vitamins, C, D. E, and K. An understanding of these facts holds great promise for better health of the human race through a wiser choice of foods. It has recently been found that plants as well as animals use vitamins in their metabolic machinery, and a study of their formation in plant cells and their role in nutrition has led t o important discoveries in some of the fundamental bodily processes which are common t o all living things. Finally, plants are notable for the healing substances which they alone can make. Herb doctors were the &st botanists. Drugs of all sorts have long been obtained from the vegetable kingdom. I n recent months this curative power of plant products has been emphasized by the discovery of the wonderful new drug penicillin, formed by a simple plant mold. This is only a beginning, for streptomycin, streptothrycin, and other substances from lowly plants may prove even more important in the control of infections and disease. These unique abilities of plant tissue t o bring about the hasic chemical unions which nnderlv all oreanic - comoounds are lmpartant in the production not only of fowl and hcolingagentz but of many other thingi. \Veal, fihrrc, rubber, and hosts of other prlxiucts have long k e n the corrcern of a~riculturrand forestry. and will continue t o be. In recent years, however, a new and significant field for the use of plant products has been opened through the immense vroaess made in svnthetic chemistry. We have learned that &bier can be produced in a factory i s well as in a rubber tree. Fibers, plastics, and a host of similar things are now the products of industry as well as of agriculture, and in the years which lie ahead this fact promiser great changes in our economic life. The postwar world may be largely built of new synthetic materials. Give a chemist sugar or cellulose or the simple compounds formed from them and he can make almost anything under the sun. B u t a n d here is the significant fact-he must have one of these simple filalant-mode compounds to begin with. The cleverest chemist is not vet able t o verform these basic svntheses on which all else depends, nor d w s it wrrn likely that he will do so for a long time, a t least on a commercial scale. W e must still depend on the cheap lahor of sun and soil nnd leaf for many of the raw materials of industry. We shall probably have t o turn to this same source in the future for another great need as well-the power t o run our mechanized civilization. Coal and vetroleum. derived from plants of ages past, will not last forever, and as they become scarce, the products of plant life today, rich in energy locked up in them from the sun, will be invaluable. Alcohol, already an important fuel, can now be made from sawdust and other plant wastes a t the rate pf about 50 gallons per ton, and petroleum-like c a n pounds are produced from the same source. All this means a new direction in the near future for the development of agriculture and forestry. We shall more and more use the synthetic ability of plants not simply for fmds or for
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specific industrial materials hut for those simple and really basic plants, for they all depend on the unique productive capacity of raw materials like sugar, starch, cellulose, and proteins from which members of the plant kingdom. Surely there are few places the industrial chemist can in turn make somuch. Here the whole where fundamental research is likely t o yield richer returns than plant can be used, including much material which is wasted to- on this question of the ability of those tiny laboratories, the cells day. I n this new program forestry will have increased signifi- of plants, t o perform the basic chemical unions on which life and cance, for an acre of trees makes considerably more actual plant civilization so depend. We still have far t o go in knowledge of product per year on the average than an acre of cultivated biochemistry and biophysics before we shall understand some of craps. The tropics with their high temperatures and other the simplest activities of living things. I n this fertile field plant favorable conditions for plant growth will mare and more attract scientists and their collaborators have already made good progthe attention of producers for agriculture and industry. The ress, but the biggest problems are still unsolved. In finding immense reservoir of plant life in the sea, still untouched by man answers t o them we shall not only contribute t o man's economic save in the use of fish and other animals which live on marine welfare hut-what is perhaps more important-we shall gain a clearer insight into the mysterious precesses of life itself. There plants, is destined t o be of ever greater economic importance. . All these sources present many problems t o the student of is good hunting ahead. Reprinted with the permission of the United States Rubber Company.
