Immunocytolocalization of CDSP 32 and CDSP 34, two chloroplastic drought-induced stress proteins in Solanum tuberosum plants

Two chloroplastic proteins, named CDSP 32 and CDSP 34 for chloroplastic dro ught-induced stress protein of 32 and 34 kDa, were previously shown to be s ubstantially synthesized in Solanum tuberosum plants subjected to water def icit. We investigated the localization of CDSPs in leaf chloroplasts from c ontrol and wilted potato plants using immunocytochemistry. Observation of e lectron micrographs did not reveal any important change in plastid structur es of drought-stressed plants, except an increased number and a larger size of plastoglobuli. In well-watered plants, very little labeling correspondi ng to CDSP 32 was detected. Consecutively to water stress, a higher abundan ce of CDSP 32 was revealed, the protein being exclusively localized in the stroma. Immunocytochemical data indicated the presence of some CDSP 34 prot ein in well-watered plants and confirmed its accumulation upon water defici t. CDSP 34 was found to be preferentially associated with stromal lamellae thylakoids, but some protein was revealed in the stroma. No association of CDSP 34 with grana and plastoglobuli was noticed in chloroplasts from contr ol and stressed plants. (C) Elsevier, Paris.