Seed potato tubers

Potatoes are usually grown from seed potatoes (tubers) or "buds (tiny tissue-cultured tubers), but a few cultivars, such as Explorer and Homestead Hybrid , are grown from true seeds. Prevent problems by planting only certified disease-free tubers. Planting true seeds or buds also helps avoid many tuber-borne diseases. 

In non-green tissues (soya seeds, potato tubers, apple embryos) molecular species of PC containing llnolelc acid (18 2/16 0, 18 2/18 2 and 18 2/18 1) are predominant. 

Potatoes are always grown from tubers. Always buy certified seed potatoes from a reliable source. They usually grow better if chitted before planting (see panel, opposite). Bulb onions and shallots can be grown from seed, but most... 

Seed potatoes usually appear in nurseries, or are shipped by mailorder suppliers, in late winter to early spring, in order that they may be "chitted" for a few weeks before planting out. Lay out the tubers in shallow trays—egg cartons near right) are ideal. Place the end with the most "eyes" (dormant buds) uppermost. Put them in a light, warm place until they sprout. Once frost has become rare and the soil has warmed up, plant them out far right) with the sprouted end uppermost. 

Starch, a reserve polysaccharide widely distributed in plants, is the most important carbohydrate in the human diet. In plants, starch is present in the chloroplasts in leaves, as well as in fruits, seeds, and tubers. The starch content is especially high in cereal grains (up to 75% of the dry weight), potato tubers (approximately 65%), and in other plant storage organs. 

Pringle, R. T. (1996). Storage of seed potatoes in pallet boxes. 2. Causes of tuber surface wetting. Potato Research, 39,2230240. 

Multiple forms of soluble starch synthases are present in barley endosperm,178 pea seeds,43 179 wheat endosperm,180482 maize endosperm,174 183-186 potato tuber,187 189 Arabidopsis,190 rice seed,191 192 Chlamydomonas reinhardtii,m sorghum seeds, teos-inte seeds and spinach leaf (the latter three are reviewed in references 2,7 and 27). 

Potato tuber BE Maize endosperm BE I Maize endosperm BE II Rice seed BE 1 Rice seed BE 3 coli glycogen BE 6. subtilis a-amylase 6. sphaericus cyclodextrinase... 

As indicated in Table 4.12, four regions which constitute the catalytic regions of amylolytic enzymes are conserved in the starch-branching isoenzymes of maize endosperm, rice seed and potato tuber, and the glycogen-branching enzymes of E. coli.286,281 It would be of interest to know whether the seven highly conserved amino acid residues of the a-amylase family listed in bold letters in Table 4.12 are also functional in branching enzyme catalysis. Further experiments, such as chemical modification and analysis of the three-dimensional structure of the BEs, would be needed to determine the nature of its catalytic residues and mechanism. 

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