Reduced photoinhibition with stem curling in the resurrection plant Selaginella lepidophylla

Abstract

Selaginella lepidophylla, the resurrection plant, curls dramatically during desiccation and the hypothesis that curling may help limit bright light-induced damage during desiccation and rehydration was tested under laboratory conditions. Restraint of curling during desiccation at 25° C and a constant irradiance of 2000 μmol m s significantly decreased PSII and whole-chain electron transport and the F/F fluorescence yield ratio following rehydration relative to unrestrained plants. Normal curling during desiccation at 37.5°C and 200 μmol m s irradiance did not fully protect against photoinhibition or chlorophyll photooxidation indicating that some light-induced damage occurred early in the desiccation process before substantial curling. Photosystem I electron transport was less inhibited by high-temperature, high-irradiance desiccation than either PSII or whole-chain electron transport and PSI was not significantly affected by restraint of curling during desiccation at 25°C and high irradiance. Previous curling also helped prevent photoinhibition of PSII electron transport and loss of whole-plant photosynthetic capacity as the plants uncurled during rehydration at high light. These results demonstrate that high-temperature desiccation exacerbated photoinhibition, PSI was less photoinhibited than PSII or whole-chain electron transport, and stem curling ameliorated bright light-induced damage helping to make rapid recovery of photosynthetic competence possible when the plants are next wetted.

Photoprotection in plants: a new light on photosystem II damage

“…Interruption of the diurnal heliotropic leaf movement causes acceleration of photoinhibition in bean (Phaseolus vulgaris) plants [44,46]. In another example, desiccation-tolerant pteridophytes, Selaginella lepidophylla, curl their stems during drought and avoid photoinhibition [47]. Given that the extent of photodamage to PSII is directly associated with incident light intensity, it is conceivable that heliotropic leaf movement helps prevent photodamage to PSII that is related to absorption of light by the OEC (Figure 2).…”

Poikilohydry and homoihydry: antithesis or spectrum of possibilities?

“…3a–b). The lack of obvious wilting is due to the even shrinking of the mesophyll cells and intercellular spaces, compared with the collapse of mesophyll cells and enlargement of intercellular spaces that occurs in sensitive species (Lebkuecher & Eickmeier, 1991). Leaf area can decrease by as much as 85% in Craterostigma as the leaves contract and curl during desiccation.…”

Chlorophyll fluorescence in the resurrection plant Selaginella lepidophylla (Hook. & Grev.) Spring during high-light and desiccation stress, and evidence for zeaxanthin-associated photoprotection

“…This is especially important because additional environmental stresses common to desert environments that further reduce carboxylation potential (i.e. water and temperature stresses) may enhance the potential for photoinhibitory damage (Powles 1984;Lebkuecher and Eickmeier 1991).…”