Potato plant leaves

FIG. 17 Resting and action potentials of a potato plant after (a) pinch along the midrib in the center of the young terminal leaflet by forceps (b) thermal shock of terminal leaflet leaf by a flame. The plants were given water every other day and kept at 20° C. Distance between Ag/AgCl electrodes (a) 5 cm, (b) 5 cm, and (c) 9 cm. (From Ref. 7.)... 

Carnegie, S.F. and Colhoun, J. (1982). Susceptibility of potato leaves to Phytophthora infestans on potato plants in relation to plant age and leaf position , Phytopathology. Z, 104, 157-167. 

In tomato and potato plants, two families of Pis have been identified that show wound-inducible expression. Within 48 h after wounding of leaves of these plants, up to 2% of leaf protein content is made up of protease inhibitors. Potato type I (Potl) inhibitors are not only expressed in wounded leaves but also in tissue of leaves away from the site of attack. ° This finding prompted the search for a hormone or inducing factor that carries the signal for enhanced inhibitor expression through the plant system. Systemin, an 18-residue peptide hormone, has since been reported to induce more than 15 genes of defense nature in tomatoes. ... 

Beetles are attracted by volatiles of several solanaceous plants (27). The collection and characterization of compounds emanating from potato plants resulted In the Identification of general green leaf volatiles such as hexanol, hexenols and hexenal, which elicit a positive response (28). But the specific compounds that enable the Insects to recognize their solanaceous hosts still remain a mystery. 

Polyphenol Oxidases. Plant trichomes and their exudates confer resistance to a variety of insects (54-56). In solanaceous plants, such as the tomato and potato, trichomes contain polyphenol oxidases and catecholic phenolics (e.g., caffeic and chlorogenic acids), which contribute to resistance to a variety of insect pests. In the potato plant, the polyphenol oxidases and phenolics are separated in different trichomes. When insects, such as aphids or leaf hoppers, walk across the surface of the plant they break the two types of trichomes. Trichomal fluids are liberated and, upon mixing, polymerize as a result of polyphenol oxidase activity on catechols, forming an often lethal adhesive trap for the insects (52,58) In tomato plants, the polyphenol oxidase and chlorogenic acid are separated by intracellular compartments, but upon breakage of trichomes by insects, polymerization and physical entrapment occurs (54). 

The life cycle of the potato plants cultivated today is completely asexual (i.e., tuber to sprout to plant to tuber). When rapid leaf growth slows down, the plant begins to form flowers, and underground stems (stolons) begin to branch out and swell at their tips. Sucrose is sent from the mature leaves, the sources, to the rest of the plant and the stolons, the sinks. The starch is deposited at the ends of the stolons, forming tubers. 

During each of these periods, there are changes in coverage of the soil by the crop and LAI. This affects spray deposition both on the leaf canopy and on the soil beneath. This is shown in Figures 3.6 and 3.7 for conventional hydraulic spraying and air-assisted spraying. In Figure 3.5 the results are presented for the spray deposition in the potato plant. 

Leaf juice (potato plants) Beindel and Biekeetelb [37] ... 

Heemann V, Brtimmer U, Paulsen G, Seehofer F (1983) Gomposition of the leaf surface gum of some Nicotiana species and Nicotiana tabacum cultivars. Phytochemistry 22 133-135 Heftmann E (1983) Biogenesis of steroids in Solanaceae. Phytochemistry 22 1843-1860 Heftmann E, Schwimmer S (1972) Degradation of tomatine to 3P-hydroxy-5a-piegn-16-en-20-one by ripe tomatoes. Phytochemistry 11 2783-2787 Heftmann E, Weaver ML (1974) 26-Hydroxycholesterol and cholest-4-en-3-one, the first metabolites of cholesterol in potato plants. Phytochemistry 13 1801-1803 Hegnauer R (1973) Chemotaxonomie der Pflanzen, vol 6. Birkhauser Verlag Basel, Switzerland, pp 420-430 446-449... 

Holtgrefe S, Bader KP, Horton P, Scheibe R, vonSchaewen A, and Backhausen JE. Decreased content of leaf ferredoxin changes electron distribution and limits photosynthesis in transgenic potato plants. Plant Physiol. 2003 133 1768-1778. 

In the quest to find other plants that are suitable as bioreactors, various monocoty-ledonous and dicotyledonous species have been tested. These include corn [16], rice and wheat [17], alfalfa [18], potato [19, 20], oilseed rape [21], pea [22], tomato [23] and soybean [24]. The major advantage of cereal crops is that recombinant proteins can be directed to accumulate in seeds, which are evolutionar specialized for storage and thus protect proteins from proteolytic degradation. Recombinant proteins are reported to remain stable in seeds for up to five months at room temperature [17] and for at least three years at refrigerator temperature without significant loss of activity [25]. In addition, the seed proteome is less complex than the leaf proteome, which makes purification quicker and more economical [26]. 

Clockwise from top left) Plant problems Pea plants stressed by drought and heat leaf yellowing between the veins, a common symptom of mineral deficiency red currant bush with most of its leaves stripped to skeletons by the pest gooseberry sawfly the fungal disease potato blight... 

Native to tropical America, sweet potato (I. batatas) is a perennial morning glory vine that has been cultivated for over 5,000 years for its edible tubers in Mexico, Central and lowland South America, and the West Indies. Today, sweet potato is cultivated around the world, especially in developing countries (Plate 4). A decoction made from the leaves of this plant is used in folk remedies as a gargle to treat mouth and throat tumors, and poultices are prepared for inflammatory tumors (64). In Mexico, leaf decoctions are considered to be of cold nature , to reduce excessive body heat, contemporarily defined as such illnesses as diarrhea, dysentery, heart disease, stomach distress, fever, and gastrointestinal infection. In Chinese traditional medicine, the tubers have been used as a medicinal herb to eliminate secretion in perceived abnormal quantities of blood or other body fluids (79). 

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