Dissecting grass nuclear genome organisation at the cytomolecular level using the model genus Brachypodium

Modern molecular cytogenetics amalgamates various methodological approaches of cytology, molecular genetics and advanced digital image acquisition, processing and analysis. It focuses on the study of nuclear genomes at the microscopic level. Advanced cytomolecular techniques, such as fluorescence in situ hybridisation (FISH) with evermore sophisticated probes, offer unprecedented insight into chromatin organisation at various phases of the cell cycle. An excellent example is chromosome painting which uses pools of chromosome-specific BAC clones, and enables the tracking of individual chromosomes not only during cell division but also during interphase.

Many plants, including economically important cereals and forage grasses, usually have large genomes saturated with repetitive DNA, which hampers detailed molecular cytogenetic analyses. Therefore, the cytomolecular organisation of the vast majority of plant genomes is still rather poorly understood, compared to that of many animals, particularly those of mammals. Model organisms possess a set of features, which makes them more amenable to scientific investigation than others. One relatively recent and rapidly developing model system contains representatives of the Brachypodium genus, particularly B. distachyon. This genus comprises 15–20 species with small, and in some cases, sequenced and resequenced genomes with a low repeat content, different basic chromosome numbers, size, morphology and ploidy levels. These species also have interesting phylogeny, short life cycles and simple growth requirements, and are subject to a rapidly and continuously growing repertoire of experimental tools.

Robert Hasterok is the leader of the Brachypodium Group at the University of Silesia in Katowice, Poland. From the very beginning he was a proponent of the cytomolecular analyses of Brachypodium species and has the expertise in this field, as shown by numerous publications in high impact journals. He was also one of the founders of the International Brachypodium Initiative and actively participated in the B. distachyon whole genome sequencing project. His current projects aim to use Brachypodium species for research of various aspects of grass genome organisation using cytomolecular approaches, including: (i) karyotype structure and evolution, (ii) distribution of chromosome territories and domains within the interphase nucleus, (iii) dynamics of epigenetic modifications of chromatin during embryo development and cell differentiation, (iv) the true nature of selective rRNA gene inactivation, (v) intraspecific epigenetic variation in natural populations, (vi) instability of a small grass genome subjected to mutagenic treatments, and (vii) meiosis and chromosome pairing control.