After a wound-desiccation stress, plant tissues can secrete products that have specific cytotoxicity against melanoma B16 cells. Healthy plant or animal cells were not susceptible to these products. Secretion of the active product varied with the plant species and the plant organs. The secretion of tubers of yam (Dioscorea cayenensis Lam), cassava (Manihot esculenta), Jerusalem artichoke (Helia...

Starch is a major food supply for humanity. It is produced in seeds, rhizomes, roots and tubers in the form of semi-crystalline granules with unique properties for each plant. Though the size and morphology of the granules is specific for each plant species, their internal structures have remarkably similar architecture, consisting of growth rings, blocklets, and crystalline and amorphous lamel...

In several vegetable species a relationship between the metabolism of active oxygen species and breakage of dormancy has been established. However, scarce information is available on the role of oxidative stress in potato tubers. The purpose of this investigation is to study the effect of CAT genetic modification on the dormancy break of potato tubers. A transgenic approach with partial repress...

Potato (Solanum tuberosum L. cv. Norland) explants, consisting of a leaf, axillary bud, and small stem segment, were used as a model system to study the influence of spaceflight on the formation of sessile tubers from axillary buds. The explants were flown on the space shuttle Columbia (STS-73, 20 October to 5 November 1995) in the ASTROCULTURE (TM) flight package, which provided a controlled e...

Microbes emit volatile compounds that affect plant growth and development. However, little or nothing is known about how microbial emissions may affect primary carbohydrate metabolism in plants. In this work we explored the effect on leaf starch metabolism of volatiles released from different microbial species ranging from Gram-negative and Gram-positive bacteria to fungi. Surprisingly, we foun...

Storage of newly fixed carbon as starch and sucrose follows a regular daily pattern in exporting sugar beet leaves under constant day length and level of illumination. Up to the final two hours of the light period, when starch storage declines, a nearly constant proportion of newly fixed carbon was allocated to carbohydrate storage, principally starch. Sucrose is stored only early in the light ...

Tuber and root crops virtually exclusively accumulate storage products in the form of carbohydrates. An exception is yellow nutsedge (Cyperus esculentus) in which tubers have the capacity to store starch and triacylglycerols (TAG) in roughly equal amounts. This suggests that a tuber crop can efficiently handle accumulation of energy dense oil. From a nutritional as well as economic aspect, it w...

Starch is the most significant form of carbon reserve in plants in terms of the amount made, the universality of its distribution among different plant species, and its commercial importance. It consists of different glucose polymers arranged into a threedimensional, semicrystalline structure-the starch granule. The biosynthesis of starch involves not only the production of the composite glucan...

The branched glucans glycogen and starch are the most widespread storage carbohydrates in living organisms. The production of semicrystalline starch granules in plants is more complex than that of small, soluble glycogen particles in microbes and animals. However, the factors determining whether glycogen or starch is formed are not fully understood. The tropical tree Cecropia peltata is a rare ...

Plants possess two alternative biochemical pathways for sucrose (Suc) degradation. One involves hydrolysis by invertase followed by phosphorylation via hexokinase and fructokinase, and the other route-which is unique to plants-involves a UDP-dependent cleavage of Suc that is catalyzed by Suc synthase (SuSy). In the present work, we tested directly whether a bypass of the endogenous SuSy route b...