RESUMO
The analysis of structure and metabolism of a cell at a defined phase of cell cycle is often difficult because cell cycle progression in somatic tissues is asynchronous and only a fraction of cells are cycling. An elegant solution to obtain populations of cells enriched for single stage of the cell cycle is to impose the synchrony artificially. Different systems have been used to obtain synchronized populations of plant cells, including suspension-cultured cells, leaf mesophyll protoplasts and root tip meristems. Root tips have been frequently used in a variety of studies ranging from chromosome analysis to cell cycle and its regulation. Seedlings with actively growing roots may be obtained in most plant species, they are easy to handle, the experimental system is well defined, reproducible and can be easily modified for different species. This paper describes a protocol for cell cycle synchronization in root tips of Vicia faba, which is based on the use of DNA synthesis inhibitor hydroxyurea [18]. Modifications of the protocol for Pisum sativum, Medicago sativa, Hordeum vulgare, Secale cereale, Triticum aestivum, and Zea mays are also given. Flow cytometric data indicate that about 90% of root tip cells are synchronized. On average, mitotic indices exceeding 50% are obtained with the method. Synchronized cells may be accumulated at metaphase using a mitotic spindle inhibitor to achieve metaphase indices exceeding 50%.
