A comparison of photosynthetic apparatus of the detached leaves of the resurrection plant Boea hygrometrica with its non-tolerant relative Chirita heterotrichia in response to dehydration and rehydration

Comparisons of the water contents in detached leaves of Boea hygrometrica (Bunge) R. Br., and other members of the family Gesneriaceae have shown that B. hygrometrica can tolerate an extraordinarily high degree of water loss and restore its life upon rehydration. We have investigated the effects of dehydration on photosynthetic function in R hygrometrica in comparison with its non-resurrection relative Chirita heterotrichia Merr. Studies on the net photosynthetic rate, chlorophyll fluorescence emission and excitation spectra, and the kinetics of chlorophyll fluorescence induction revealed that the effects of dehydration on both species were similar insofar as photosystem 11 was more sensitive to dehydration than photosystem I. However, B. hygrometrica responded more rapidly than C heterotrichia. Although photosynthetic activity could be restored in both species upon rehydration after 2 days of dehydration, only B. hygrometrica recovered when the dehydration period was extended to 8 days. In contrast to C heterotrichia leaves, in which the levels of carotenoids decreased rapidly during desiccation, carotenoid content actually increased in B. hygrometrica leaves upon dehydration and returned to the normal level after rehydration. Non-denaturing electrophoresis revealed that the thylakoid pigment-protein complexes of B. hygrometrica were highly stable during desiccation and rehydration, whereas those of C. heterotrichia were totally destroyed after 8 days of desiccation. (C) 2003 Elsevier Ireland Ltd. All rights reserved.