Rola śmierci komórek drewna w sukcesie ewolucyjnym roślin drzewiastych

The paper describes the different types of cell death during the process of wood cell formation and terminological variety found in the literature concerned. The cell death referred to as programmed cell death (PCD), is genetically controlled and fundamental for the correct function of the whole organism of woody plants. The wood is mainly composed of the tracheary elements fulfil as conductors of water, fibers that provide the mechanical support and parenchyma cells playing an important role in the storage of water and reserve materials. The PCD of these elements constitutes the final stage of their differentiation and it is proceeded by: (i) cambial cell divisions, (ii) the enlargement of the cambial derivatives. The successive phase concerns (iii) deposition of secondary cell walls and its lignification. After that, the cell commences to digest protoplast, what means that each cell participates in the process of its own demise actively. However, the time and the sequence of the appearance of these phases are distinct among the woody cells. In the case of the tracheary elements the digestion of the protoplast occurs immediately after the tonoplast breakdown. Therefore, these cells are short−lived elements of wood. The life span of the fibers and the parenchyma cells is longer (from month for fibers and years in case of parenchyma cells). For the latter cells the positional information (distance from the cambium) and vicinity with short−lived tracheary elements are considered to be important for undergoing the process of death.