Biotransformation of potato stress metabolites rishitin, lubimin, and 15-dihydro lubimin by potato and soybean cell cultures.

Potato callus and cell suspensions of potato and soybean were exogenously supplied with potato phytoalexin rishitin, much of which was converted by both species to an unknown tenatively identified as glutinosone. Exogenous lubimin was unaffected by the potato cell culture, but was transformed to 15-dihydro lubimin by the soybean cell suspensions. The stability of the exogenous lubimin may be ascribed to a second block in the rishitin pathway of the potato cell culture.

Biotransformation of the potato stress metabolite, solavetivone, by cell suspension cultures of two solanaceous and three non-solanaceous species.

Cell suspension cultures of several plant species which were exogenously supplied solavetivone accumulated four hydroxylated derivatives. Only solanaceous cell cultures converted exogenously supplied solavetivone to sesquiterpenoid compounds identified with the plant response to biotic stress. Failure of potato cell cultures to make these compounds under biotic stress may be linked to their inability to produce adequate levels of solavetivone.

An in vitro control mechanism for potato stress metabolite biosynthesis.

Ethylene/oxygen (E/O(2)) elevates sesquiterpenoid stress metabolite (SSM) levels in potato (Solanum tuberosum L.) tuber tissue which is reacting hypersensitively. To determine whether E/O(2) retards SSM turnover, a measured amount of rishitin was applied to tuber tissue which was then incubated in air or E/O(2), and rishitin disappearance was monitored. No difference in the rate of rishitin disappearance was detected between air and E/O(2) incubations. However, tissue treated with rishitin and incubated in E/O(2) accumulated intermediates of the katahdinone and phytuberin pathways. This was not the case in rishitin-air treatments. These results suggest the dual involvement of ethylene and SSM intermediates in the regulation of the biosynthesis of SSM, compounds which may serve as phytoalexins.

Effects of Controlled Atmospheres on Production of Sesquiterpenoid Stress Metabolites by White Potato Tuber: Possible Involvement of Cyanide-resistant Respiration.

Levels of katahdinone (solavetivone), lubimin, rishitin, and phytuberin, sesquiterpenoid stress metabolites of white potato (Solanum tuberosum), were monitored in tuber slices which were challenged with an extract of Phytophthora infestans and incubated under controlled atmospheres. A mixture of ethylene in air enhanced stress metabolite production. This enhancement was amplified by higher partial pressures of oxygen. Stress metabolite production was inhibited by salicylhydroxamic acid. These results suggest the involvement of cyanide-resistant respiration in the production of potato stress metabolites, compounds which may serve as phytoalexins.

Stress Metabolites of the Potato and Other Solanaceous Plants.

The effect of stress on the chemical composition of the Solanaceae , primarily Solanum tuberosum (potato), may be profound and have significant health implications. Changes in glycoalkaloids, steroids, sesquiterpenes and other lipids that result from specific and non-specific stress are discussed. The biochemistry and toxicology of these compounds are reviewed.

Food value of red tide (Gonyaulax polyedra).

Two harvests of ocean-growing red tide, comprised mainly of Gonyaulax polyedra, were evaluated in limited trials of rat feeding. The protein of red tide (25 to 30 percent, dry basis) supported growth satisfactorily. The essential amino acid composition of the protein closely resembles that of casein, the major protein of milk. As a marine resource, plankton represents a challenge for research.