ASEPTIC MICROHYDROPONICS: A STRATEGY TO ADVANCE MICROPLANT DEVELOPMENT AND IMPROVE MICROPLANT PHYSIOLOGY

Quality management in micropropagation is concerned with maintaining high health status and genetic quality. Significant advance have been made and can be anticipated in the area of plant disease diagnostics, particularly in the development of molecular diagnostics (Cassells, 2000). Many aspects of genetic quality (physiological status, developmental status and trueness-to-type), however, have been addressed empirically by manipulation of the tissue culture media components (George, 1993; 1996). Novel techniques to improve genetic quality are now gaining acceptance, for example, based on bottom-cooling of the culture vessel (Vanderschaeghe and Debergh, 1987); use of gas-permeable vessel lids and polyurethane foam as an agar substitute (Cassells and Walsh, 1998); periodic submersion (Teisson and Alvard, 1995) and culture in bioreactors (Preil, 1991). Inoculation in vitro with biocontrol organisms to improve biotic and abiotic resistance of microplants has also been introduced (Cassells et al., 2000). Physiological quality and developmental status are discussed and parameters to monitor these properties outlined. The use of biotization and elicitors to improve biotic stress is discussed. Oxidative stress is considered as an underlying cause of poor genetic quality in microplants.