MOLECULAR CHARACTERIZATION OF CDSP-34, A CHLOROPLASTIC PROTEIN-INDUCED BY WATER-DEFICIT IN SOLANUM-TUBEROSUM L. PLANTS, AND REGULATION OF CDSP-34 EXPRESSION BY ABA AND HIGH ILLUMINATION

We previously described the accumulation of a 34 kDa thylakoid protein , named CDSP 34 for chloroplastic drought-induced stress protein, in S olanum tuberosum plants subjected to water deficit. A full-length CDSP 34 cDNA has been isolated and we report here that mature CDSP 34 is h ighly similar to two chromoplastic proteins, fibrillin from Capsicum a nnuum and CHRC (for chromoplast protein C) from Cucumis sativus, compo nents of carotenoid-accumulating structures. Northern and Western anal yses showed that both CDSP 34 transcript and protein accumulated from early stages of water deficit. In water-stressed tomato plants, simila r increases in the CDSP art-related transcript amount were noticed in wildtype and ABA-deficient flacca mutant, but protein accumulation was observed only in wild-type, suggesting a posttranscriptional role of ABA in CDSP 34 synthesis regulation. Substantial increases in CDSP 34 transcript and protein abundances were also observed in potato plants subjected to high illumination. The CDSP 34 protein is proposed to pla y a structural role in stabilizing stromal lamellae thylakoids upon os motic or oxidative stress.