Non-destructive Evaluation of the Photosynthetic Capacity of PSII in Micropropagated Plants

Abstract

A chlorophyll fluorescence parameter Fv/Fm was used for evaluation of photosynthetic capacity of micropropagated potato plantlets. Potato nodal cuttings were transplanted into glass tubes containing MS medium with different contents of sucrose. At the end of the cultures, plantlets were taken out of culture vessels after a 60 min dark treatment and Fv/Fm was measured for all measurable leaves of the plantlets using a pulse amplitude modulation fluorometer. The distribution patterns of Fv/Fm within the plantlets were changed by sucrose contents. Averaged Fv/Fm values were also affected by sucrose contents. These results suggest that Fv/Fm may change according to culture conditions and it is effective to analyze Fv/Fm for evaluation of photosynthetic capacity of cultured plantlets toward optimization of culture conditions. A system was developed for imaging chlorophyll fluorescence in leaves of potato plantlets from outside of the culture vessels and for estimating the fluorescence parameter Fv/Fm. Potato plantlets in glass test tubes were illuminated by a halogen lamp with a light fiber, the light intensity for fluorescence excitation was controlled by neutral density filters. Fluorescence was imaged by a high sensitive monochrome CCD camera. Fv/Fm was estimated from an Fo image, which was a fluorescent image under low intensity illumination (0.15 µmolm-2 s-1) after 60 min dark treatment, and an Fm image which was then acquired under high intensity illumination (2500µmolm-2 s-1). By non-destructive measurements of chlorophyll fluorescence through the wall of the culture vessel using the developed system, changes in Fv/Fm of an Fv/Fm individual leaf over culture period could be monitored.