POSITION OF WATER IN VITRIFIED PLANTS VISUALIZED BY NMR IMAGING

Vitrification of plants in vitro is a physiological abnormality of tis sue-cultured plants which causes significant losses in the micropropag ation industry. Vitrified plants are waterlogged but the position of w ater within plants has not been identified. Nuclear magnetic resonance (NMR) imaging of normal tissue-cultured, vitrified tissue-cultured, a nd glasshouse-gown leaves of Gypsophila paniculata showed the distribu tion of water within the leaves. Normal tissue-cultured and glasshouse -grown leaves had a high concentration of water within leaf vascular b undles and lower concentrations elsewhere. In contrast, vitrified leav es had a relatively even distribution of high water concentration thro ughout the leaves. When imaging parameters were changed, so that only water associated with cell membranes was shown, the images of normal t issue-cultured and glasshouse-grown leaves did not change. However, th e image of the vitrified leaves showed a general lowering of intensity across the whole of the leaf. The appearance of the NMR images, toget her with those obtained by light microscopy, suggest that the excess w ater associated with vitrified plants is located in the intercellular air spaces. The blockage of these spaces may lead to a cycle of pertur bations in the plant's physiology culminating in the development of vi trification.