Abstract
The flexibility of the thylakoid membrane of Arabidopsis thaliana during growth was reported at this meeting last year. Surprisingly, the reorganized "curly structure" found was subsequently observed in a large variety of land plants. In order to understand the functional differences between the original "linear" and the reorganized "curly" thylakoids, chlorophyll content, photosynthetic efficiency and starch content of leaves were examined. The chlorophyll content in the latter was rather higher than in the former and the a/b ratio was less in the latter. No definite differences in the CO2 assimilation rate or the parameter values of Fv/Fm, qp, ΦII and NPQ were found. However, the chloroplast with "linear thylakoid" accumulates much more starch than that with "curly thylakoid". Concluding we propose that mature chloroplasts in leaves of land plants occur in two forms and may change from one form to the other.
