Patterns of protein expression in water-stressed wheat chloroplasts

The performance of control and water-stressed 10-d-old wheat seedlings was compared. During short-term water stress (irrigation was withheld for 9 d), rates of photosynthesis and transpiration, stomatal conductance, and relative water content decreased whereas the proline content increased. Chloroplast proteins were extracted from the leaves, separated by iso-electric focusing through two-dimensional electrophoresis, and stained with CBB R-250. Differentially expressed proteins were detected and analyzed with MALDI-TOF/TOF mass spectrometry. Under water stress, 9 proteins were up-regulated whereas 11 proteins were not affected. The ribulose-1,5-bisphospate carboxylase/oxygenase (Rubisco) small and large subunits, chloride carrier/channel family, and H⁺-ATPase were up-regulated by water stress whereas membrane-bound ATP synthase subunit b and cytochrome b6-f complex were down-regulated.