NONDESTRUCTIVE VISUALIZATION IN 3 DIMENSIONS OF FREEZING EVENTS IN FLOWERS OF BLACK-CURRANT (RIBES NIGRUM L.) USING SPIN-ECHO NMR MICROSCOPY

Flowers of blackcurrant (Ribes nigrum L.) were subjected to freezing s tress in vivo, and the resulting damage examined in three dimensions u sing a spin-echo nuclear magnetic resonance imaging sequence, Increase d signal intensity was detected in the damaged flowers, particularly a t the base of the style, in T-2-weighted images, This is thought to be the result of intracellular freezing, which causes membrane damage an d leakage of cellular contents, It is proposed that this represents th e main site of damage within the flowers, The imaging of flowers of di ffering developmental ages showed larger increases in signal from full y open flowers after freezing damage compared with those in the initia l stages of bud, suggesting that the enclosed nature of the flower bud s may have a protective effect on the sensitive stylar base. The use o f three-dimensional nuclear magnetic resonance imaging provides a rapi d and effective means for the visualisation of freezing events within floral tissues; the effective resolution of the images enables greater accuracy and clarity in interpretation than hitherto possible in two dimensions. (C) 1997 Elsevier Science Inc.