Phytoecdysteroid overproduction in Polypodium vulgare prothalli

• Published in: Phytochemistry (Oxford) 1997, Vol.46 (7), p.1183-1187
• Main Authors: Reixach, Natàlia, Irurre-Santillari, Josep, Camps, Francisco, Melé, Enric, Messeguer, Joaquima, Casas, Josefina
• Format: Article
• Language: English
• Subjects: 20-hydroxyecdysone; Biological and medical sciences; Biotechnology; Chemical constitution; Eukaryotic cell cultures; fern; Fundamental and applied biological sciences. Psychology; in vitro cultures; Methods. Procedures. Technologies; Miscellaneous; phytoecdysteroids; Plant cells and fungal cells; Plant physiology and development; Polypodiaceae; Polypodium vulgare; temperature-stress; water-stress
• ISSN: 0031-9422; 1873-3700
• DOI: 10.1016/S0031-9422(97)80008-8

When P. vulgare prothalli were immersed in water at 45° for 10 hr the total production of ecdysteroids increased 23 fold. Contribution of different factors to the observed ecdysteroid overproduction are discussed. Polypodium vulgare prothalli, from in vitro cultures, showed an increase of phytoecdysteroid production when immersed in water. The degree of overproduction depended on water temperature and time used for the treatment. Although the presence of water at 25° caused an increase of phytoecdysteroid production, the highest production was detected at 45°. At higher water temperature a decrease of ecdysteroid production was observed as well as tissue necrosis, when prothalli were transferred to culture medium. A temperature increase in the absence of water did not change the phytoecdysteroid production. Using a labelled precursor we proved that de novo biosynthesis of ecdysteroids occurred when P. vulgare prothalli were immersed in water at 45°. The presence of water at 45° for 10 h increased 15 and 23 times the total production of ecdysteroids, depending if prothalli were maintained in the same water vial or changed three times during the experiment, respectively. At room temperature 20% of ecdysteroid total production was excreted into the water, whereas at 45° this amount increased to more than 97%. These results suggest that diffusion of ecdysteroids into water may occur, originating a dilution of ecdysteroid content in prothalli and an increase of ecdysteroid biosynthesis in an attempt to restore its normal intracellular levels. Different factors that may contribute to this observed ecdysteroid overproduction are discussed.