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Cadmium‐induced inhibition of photosynthesis and long‐term acclimation to cadmium stress in the hyperaccumulator Thlaspi caerulescens
Author(s) -
Küpper Hendrik,
Parameswaran Aravind,
Leitenmaier Barbara,
Trtílek Martin,
Šetlík Ivan
Publication year - 2007
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2007.02139.x
Subject(s) - hyperaccumulator , acclimatization , photosynthesis , cadmium , photosystem ii , chlorophyll fluorescence , chemistry , botany , chlorophyll , photoprotection , photoinhibition , phytoremediation , biophysics , biology , environmental chemistry , heavy metals , organic chemistry
Summary• Acclimation of hyperaccumulators to heavy metal‐induced stress is crucial for phytoremediation and was investigated using the hyperaccumulator Thlaspi caerulescens and the nonaccumulators T. fendleri and T. ochroleucum . • Spatially and spectrally resolved kinetics of in vivo absorbance and fluorescence were measured with a novel fluorescence kinetic microscope. • At the beginning of growth on cadmium (Cd), all species suffered from toxicity, but T. caerulescens subsequently recovered completely. During stress, a few mesophyll cells in T. caerulescens became more inhibited and accumulated more Cd than the majority; this heterogeneity disappeared during acclimation. Chlorophyll fluorescence parameters related to photochemistry were more strongly affected by Cd stress than nonphotochemical parameters, and only photochemistry showed acclimation. • Cd acclimation in T. caerulescens shows that part of its Cd tolerance is inducible and involves transient physiological heterogeneity as an emergency defence mechanism. Differential effects of Cd stress on photochemical vs nonphotochemical parameters indicate that Cd inhibits the photosynthetic light reactions more than the Calvin–Benson cycle. Differential spectral distribution of Cd effects on photochemical vs nonphotochemical quenching shows that Cd inhibits at least two different targets in/around photosystem II (PSII). Spectrally homogeneous maximal PSII efficiency ( F v / F m ) suggests that in healthy T. caerulescens all chlorophylls fluorescing at room temperature are PSII‐associated.