Katedra biofyziky Univerzity Palackého v Olomouci

Effects of aromatic cytokinins on senescence-induced alterations in photosynthesis.

Leaf senescence constitutes the final stage in leaf development involving multiple alterations in cell physiology and biochemistry. There are pronounced changes in chloroplasts, the structures of the photosynthetic apparatus are degraded, and photosynthetic activity declines. The progress of leaf senescence as well as the senescence-induced alterations in photosynthesis can be retarded or mitigated by plant hormone cytokinin. Today, cytokinins are well-known decelerators of leaf senescence. To study the role of cytokinins in this process, exogenous application on senescing leaves is often used. For this purpose most researchers use aromatic cytokinins, such as 6-benzylaminopurine, kinetin and meta-topolin. This chapter provides an overview of the alterations in photosynthesis during leaf senescence and how they can be affected by exogenous application of aromatic cytokinins.