Lilia Alcaraz-Meléndez

Domestication of micropropagated plants of the spice damiana (Turnera diffusa).

Tissue culture propagation was performed on the spice shrub damiana (Turnera diffusa. Willd.) using MS medium (Murashige and Skoog 1962) supplemented with different combinations of the plant growth regulators, 6-benzyl adenine (BA) and indole-3-butyric acid (IBA). Organogenesis of leaf explants from wild plants and explants from propagated cuttings was compared; only the former regenerated complete plants. The highest shooting rate (92%) occurred at a concentration of 10−7 M BA plus 10−6 M IBA. Regenerated shoots were rooted in MS medium without any plant growth regulators. Foliage productivity of the micropropagated plants under field cultivation was determined yearly over 3 years. The yield increased annually for the first two years. The quantity of essential oils in propagated plants was similar to that of wild plants growing nearby. We propose tissue culture propagation of damiana as a viable means of domestication of this wild plant for semi-arid agriculture in Mexico. Commercial propagation would help to conserve wild populations of damiana that are currently threatened by overharvesting.

Morphological comparison of damiana (Turnera diffusa, Willd.) regenerated in vitro from leaves cultured in solidified medium and liquid cultures

Damiana, a shrub of arid and semi-arid regions, is an important socio-economic plant. Its leaves and stems are used for flavoring and infusion. Damiana is reported to be a nervous system stimulant, aphrodisiac, and diuretic. The only source of stems and leaves are wild plants, and conditions for seed germination and propagation are not known. Damiana plants were micropropagated in liquid culture and solidified medium, and grown in field. Differences in growth were observed between the two types of plants.

Variation in polar-group content in lipids of cowpea (Vigna unguiculata) Cell cultures as a mechanism of haloadaptation

Callus and cell suspension cultures of cowpea (Vigna unguiculata) were induced with 2,4-dichlorophenoxyacetic acid and grown at different NaCl concentrations. The cell biomass yield and its total lipid content decreased with increasing salinity. However, while the hexose content in lipids was higher, the amount of lipid phosphorus was significantly lower in both agar and cell suspension cultures. Ion-transport rates with artificial membranes prepared with different lipid fractions showed that lipids from cells grown in a saline medium were less permeable to Na+ and to Cl- than those grown in a non-saline medium. Also the permeability of membranes prepared with glycolipids was lower than those prepared with phospholipids and whole lipids. Apparently, the increase of hexose/phosphorus ratio in membrane lipids is induced in response to the halo-adaptation process.

Antioxidant responses of damiana (Turnera diffusa Willd) to exposure to artificial ultraviolet (UV) radiation in an in vitro model; part I; UV-C radiation.

INTRODUCTION Ultraviolet type C (UV-C) radiation has higher energy than the UV-B radiation and has been less studied because it is completely absorbed by the ozone layer. However, artificial UV-C radiation can generate diverse modifications in the plants. Given that exposure to UV-C for short periods of time increases the antioxidant content, improving the appearance and shelf-life of products, its potential application in postharvest treatments to modify the antioxidant content of medicinal plants, such as damiana (Turnera diffusa), is novel and relevant. OBJECTIVE To determine the effects of UV-C radiation on enzymatic and non-enzymatic antioxidant defenses, as well as oxidative damage levels, in damiana (Turnera diffusa) plants in vitro. RESULTS UV-C radiation decreased superoxide dismutase (SOD, EC 1.15.1.1) and total peroxidases (POX, EC 1.11.1) activities, the concentration of chlorophylls (a and b), carotenes, vitamin C, and total antioxidant capacity. UV-C radiation increased the phenolic compound levels in damiana. Loss of antioxidant defenses was higher in damiana plants exposed to higher UV-C doses and/or for longer periods. This study suggests that UV-C radiation induces oxidative stress, evidenced as increased protein carbonyls and phenolic compound content, in damiana (T. diffusa). CONCLUSION Low dose, short exposure to UV-C stimulates phenolic compound content in damiana. Thus, controlled UV-C treatments could be used as postharvest treatment to increase phenolic compound content in damiana plants.