Plant cytogenetics : a re-birth in Twenty-first Century

Abstract

During the last few decades of the last century, emphasis on classical plant cytogenetics largely declined due to the emergence of molecular biology tools. In the realm of plant cytogenetics, this marked the end Era 1 dealing with the study of structural and numerical changes of chromosomes, and also Era 2 dealing with DNA content and composition (repetitive vs unique DNA). In Era 3, during 1980s and 1990s, molecular markers were extensively used for construction of molecular linkage maps and physical maps of chromosomes in a variety of plants. Molecular markers were also used and for the study of marker-trait associations for marker-aided selection (MAS). Later, in Era 4, starting in mid 1990s, two major areas of research took over; these were plant genomics involving whole genome sequencing (sequencing of the genomes of Arabidopsis thaliana and Oryza sativa), and plant epigenomics involving study of nuclear architecture, chromatin remodeling (chromatin remodeling complexes, and histone modifications and variants; the histone code). Some details of chromosome organization within the nucleus, and genomics/ epigenomics research are discussed in this article.