<p style="text-align: justify;"><big><b>General Description</b></big></p>

<p style="text-align: justify;">This description has been adapted from a biology document published by the Canadian Food Inspection Agency (CFIA 1996). The potato (<i>Solanum tuberosum</i>) belongs to the Solanaceae family. This family includes, among 2000 other species, the tomato (<i>Lycopersicum esculentum</i>), sweet pepper (<i>Capsicum annuum</i>), eggplant (<i>Solanum Melongena</i> var. esculentum), tobacco (<i>Nicotiana tabacum</i>), and petunia (<i>Petunia hybrida</i>). The genus Solanum is a polymorphous and largely tropical and subtropical genus containing more than 1000 species (Fernald 1970). The potato is one of the world&#39;s most important crops, following wheat, maize, and rice. It has weak stems that grow to a maximum of three feet, long pinnate leaves, ovate leaflets with smaller ones disposed along the midrib. The flowers are white, purple, pinkish, or bluish, in clusters, usually with a five parted corolla and exserted stamens with very short filaments. Some varieties are male sterile, suffer from abscission of flowers, and rarely produce fruits. The fruits are yellowish or green, globose, less than one inch in diameter, some lack seeds, but others may contain several hundred. The fruits are inedible to humans, due to the presence of toxins (Hortus Third 1976). Solanum species have an initial chromosome number of 12, but polyploidy is prevalent in both wild and cultivated potatoes. In North America, the crop is grown primarily for human consumption and for seed. In some areas, starch is manufactured from surplus production and cullage. Starch manufactured from potatoes has a wide range of end uses. The most extensive use is for sizing and coating in the paper industry. In the food industry, starch may be used in the preparation of instant puddings, in the manufacture of ice cream, as an additive to breads and biscuits, as a thickener in soups and a variety of other preparations in home cooking. Potatoes utilized for food may be fresh or processed; the cultivars grown for processing are also acceptable for fresh consumption or table stock, while some table stock cultivars are not suitable for processing and are limited to the fresh market. Fresh potatoes are usually prepackaged in consumer packs or may be sold at retail in open displays. The single most important processed product is frozen french fried potatoes and there is a significant production of potato chips. The processed potato products are usually preserved by freezing, canning and dehydrating and are prepared in a variety of consumer products. Tubers used as livestock feed are usually cullage from fresh pack operations, surplus production or waste from processing plants.</p>

<p style="text-align: justify;"><big><b>Reproduction</b></big></p>

<p style="text-align: justify;">The cultivated potato is an annual and may be reproduced by seed although the commercial crop is propagated from tuber &laquo;seed&raquo; pieces (Rowe 1993). In the context of true seed production, the degree to which flowering occurs, the duration of flowering and the response of flowering behaviour to environmental conditions is greatly influenced by cultivar (Burton 1989). The environmental conditions that influence flower initiation and development include light intensity, quality and duration (day length), temperature, water supply and available soil nutrients. Flower development does not ensure fruit set. Pollen sterility is frequently encountered, in which case pollinating insects may not be attracted due to poor nectar production, and ovule sterility is also occasionally experienced. True seed production is practised in breeding programs, and under greenhouse conditions. It requires skilled manipulation of variables to be successful. True seed production in the natural environment varies with cultivars and weather conditions. Many varieties do not produce any seed, while some varieties are either self-pollinated or cross-pollinated and do produce seeds. <big><b>Center of Origin</b></big> The potato originates from regions of high elevation of South America. The area of first domestication is reasoned to be the area where wild diploids are still found and where the greatest diversity of cultivated forms can still be found, and is identified as the high plateau of Bolivia and Peru, in the general region of Lake Titicaca (Hoopes &amp; Plaisted 1987). Many authors have traced the origin and distribution of the potato (Burton 1989; Dodds 1965; Hawkes 1967; Howard 1970; Salaman 1949; Simmonds 1976). These authors essentially agree that the significant species considered to be the progenitors of the cultivated potato are from South America. Simmonds (1976) indicates these may be found to 45S latitude in South America and to 40N in North America.</p>

<p style="text-align: justify;"><big><b>Outcrossing</b></big></p>

<p style="text-align: justify;">Less than a tenth of the Solanum species are tuber-forming and, so far as is known, these occur only in the Americas, between mid-USA to the north and southern Chile and Argentina to the south (Burton 1989). <i>Solanum fendleri</i> and <i>S. jamesii</i>, found in the southern part of the United States, can produce hybrids with <i>S. tuberosum</i> plants under controlled laboratory conditions (Adiwilaga &amp; Brown 1991). These species occupy dry forest at high altitudes, and therefore are quite unlikely to cross with cultivated potato plants under natural conditions due to geographical separation. As a general rule, <i>Solanum tuberosum</i> can only hybridize naturally with Solanum species that form tubers (Dale <i>et al</i>. 1992; Evenhuis &amp; Zadoks 1991), none of which are present in Canada (Love &amp; Pavek 1994). Gene introgression to related native species through hybridization is therefore not possible (Love &amp; Pavek 1994 and other authors cited previously).</p>

<p><big><b>References</b></big></p>

<ol>
	<li>Adiwilaga, K. D. &amp; C. R. Brown (1991) Use of 2n pollen-producing triploid hybrids to introduce tetraploid Mexican wild species germplasm to cultivated tetraploid potato gene pool. <i>Theor. Appl. Genet.</i> <b>81</b>: 645-652.</li>
	<li>Burton, W. G. (1989) The potato - 3rd ed. John Wiley &amp; Sons Inc. New York. 742 pp.</li>
	<li>CFIA (1996). Regulatory Directive T-1-09-96 : The Biology of <i>Solanum tubersum</i> (L.) (Potato). The Canadian Food Inspection Agency ( http://www.cfia-acia.agr.ca/english/plaveg/pbo/t10996e.shtml )</li>
	<li>Dale, P. J., H. C. McPartlan, R. Parkinson, G. R. MacKay and J. A. Scheffler (1992) Gene dispersal from transgenic crops by pollen. In: Proceedings of the second international symposium on the biosafety results of field tests of genetically modified plants and microorganisms. Goslar Germany, 1992. pp 73-77.</li>
	<li>Dodds, K. S. (1965) The history and relationships of cultivated potatoes. In: J. B. Hutchinson, ed., Essays in crop plant evolution, London, pp.123-41.</li>
	<li>Evenhuis, A. &amp; J. C. Zadoks (1991) Possible hazards to wild plants of growing transgenic plants. A contribution to risk analysis. <i>Euphytica</i> <b>55</b>: 81-84.</li>
	<li>Fernald, M. L. (1970) Gray&#39;s manual of botany. A handbook of the flowering plants and ferns of the central and northeastern United States and adjacent Canada. D. Van Nostrand Co. p.1252.</li>
	<li>Hawkes, J. G. (1967) The history of the potato. F. Roy. hort. Soc.: 92; 207-24; 249-62; 288-302; 364-65.</li>
	<li>Hoopes, R. W. and R. L. Plaisted (1987) Potato. In: Principles of cultivar development. Volume 2. Crop species. W. R. Fehr, E. L. Fehr, H. J. Jessen, eds. Macmillan Publishing Company, N.Y. pp. 385-436.</li>
	<li>Hortus Third (1976) A concise dictionary of plants cultivated in the United States and Canada. Liberty Hyde Bailey Hortorium, ed. Macmillan Publishing Company, Cornell University pp.903-04; 1054.</li>
	<li>Howard, H. W. (1970) Genetics of the potato: Solanum tuberosum. Logos Publishing, London. 126 pp.</li>
	<li>Love, S. L. &amp; J. J. Pavek (1994) Ecological risk of growing transgenic potatoes in the United States and Canada: potential for vegetative escape or gene introgression into indigenous species. <i>Am. Potato J.</i> <b>71(10)</b>: 647-58.</li>
	<li>Rowe, R. C. (1993) Potato Health Management. The American Phytopathological Society, St Paul, Minnesota, USA, pp. 4.</li>
	<li>Salaman, R. N. (1949) The history and social influence of the potato. University Press. Cambridge. 685 pp.</li>
	<li>Simmonds, N. W. (1976) Evolution of Crop Plants. Longman, London and New York. 339 pp. Weed Seed Order (1986) Canada Seeds Act.</li>
</ol>
