ACTA BIOLOGICA CRACOV1ENSIA Series Botanica 39: 69-77, 1997 PL ISSN 0001-5296 ON HETEROCHROMATIN IN KARYOSYSTEMATIC STUDIES ANDRZEJ JOACHIMIAK 1,2 , ADAM KULA 2 , AND ALEKSANDRA GRABOWSKA-JOACHIMIAK 2 1 Department of Plant Cytology and Embryology, Institute of Botany, Jagiellonian University, ul. Grodzka 52, 31-044 Krakw, Poland 2 Cytogenetics Group in the Department of Plant Breeding and Seed Science, The Agricultural University of Cracow, ul. £obzowska 24, 31-140 Krakw, Poland Received March 7, 1997; revision accepted April 7, 1997 The application of chromosome banding methods for plant karyosystematic studies is analyzed. The authors discuss ways of constructing C-band idiograms and interpretating the results of C-banding studies with respect to the polymorphism of heterochromatin and its histochemical differentiation. The role of quantitative changes of heterochromatin in evolution, its functional effect, and the division into dispensable and indispensable heterochromatin are presented. An overview of the recent literature on this subject is also given. Key words: C-banding, genome structure, heterochromatin, karyotype analysis, plants. INTRODUCTION Banding chromosome studies have been carried out for almost thirty years (for plant chromo- somes: CASPERSSON et al., 1969; VOSA and MARCHI , 1972; SCHWEIZER, 1973; MARKS, 1974), and their potential importance for karyotype analysis was noticed at the very beginning. In animal and human karyotype analysis this has resulted in the development of routine methods which are characterized by high reproducibility and resol- ution, mainly modification of G-banding and R- banding methods (COMINGS, 1978; SUMNER, 1982; JOACHIMIAK, 1983a). These relatively stable, species-specific band patterns can serve as the basis for elaboration of standard karyotypes; they are also useful material for comparative studies. A good example is found in studies on human and great apes karyotypes, which are the basis for interesting elaborations of karyotype evol- ution within the group Hominidae and of the relationships between species (SEUANEZ, 1979). G- and R- band patterns of some mammalian chromosome segments have been constant for several, even tens of millions of years; for example, the long arm of Chinese hamster chromosome 6 and mouse chromosome 2, containing the group of oncogenes (SRC, ABL, AK1, ADA and TTPA), possess identical G- band patterns (STALLINGS et al., 1985). In plant karyotype analysis, the potential ad- vantages of chromosome banding have not been fully utilized so far. Among the many reasons for this, the main ones are these: (1) the lack of routine, highly reproducible methods for proper preparation of the cell material before chromo- some banding (e.g., quick methods of in vitro cell culture, cell cycle synchronization, and spreading cell suspension on microscope slides); (2) the small choice of highly reproducible banding methods suitable for routine use; and (3) difficult- ies in elaboration and interpretation of the results obtained in chromosome banding studies. The first two reasons are associated with the specific character of plant material: - Because of the presence and cohesion of cell walls, proper preparation of the material for banding studies is difficult; it usually requires mechanical crumbling and squashing of re- latively large pieces of meristematic tissue. Such pdf Machine A pdf writer that produces quality PDF files with ease! Produce quality PDF files in seconds and preserve the integrity of your original documents. Compatible across nearly all Windows platforms, if you can print from a windows application you can use pdfMachine. Get yours now!