Rare and endangered plants possessing crassulacean acid metabolism (CAM), such as cacti, usually present limited reproductive capacities and very slow growth rates. The use of in vitro culture can overcome these difficulties. The massive in vitro production of new propagules which result in totally regenerated plants is described for two endangered cacti, Obregonia denegrii Fric. and Coryphantha minima Baird. A comparison of in vitro and ex vitro growth rates demonstrated that the in vitro environment notably accelerates cacti growth. Malic acid titratable acidity indicated that increase of the net carbon dioxide uptake is associated with active growth. This might be related to particular factors of the in vitro environment such as the high relative humidity inside the culture vessels, or growth regulators supplemented to the growth media. In vitro-derived cacti showed a proficient re-establishment capability which could be related to their succulence since water loss during transplantation did not represent a crucial hydric stress. Succulence and plasticity of the CAM metabolic pathway in plants like cactus, represent some possible advantageous for the application of in vitro propagation techniques in a number of endangered, succulent plants like members of the Cactaceae, Agavaceae, Orchidaceae, or Bromeliaceae families. # 1999 Elsevier Science B.V. All rights reserved.
Download Full PDF Version (Non-Commercial Use)