B Chromosomes in Genus Sorghum (Poaceae).

Martina Bednářová,Miroslava Karafiátová,Eva Hřibová,Jan Bartoš

doi:10.3390/plants10030505

Martina Bednářová, Miroslava Karafiátová + Show 2 more

Open Access

https://doi.org/10.3390/plants10030505

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Abstract

B chromosomes (Bs) are supernumerary dispensable genomic elements that have been reported in several thousand eukaryotic species. Since their discovery, Bs have been subjected to countless studies aiming at the clarification of their origin, composition, and influence on the carriers. Despite these efforts, we still have very limited knowledge of the processes that led to the emergence of Bs, the mechanisms of their transmission, and the effects of Bs on the hosts. In the last decade, sophisticated molecular methods, including next-generation sequencing, have provided powerful tool to help answer some of these questions, but not many species have received much attention yet. In this review, we summarize the currently available information about Bs in the genus Sorghum, which has so far been on the periphery of scientific interest. We present an overview of the occurrence and characteristics of Bs in various Sorghum species, discuss the possible mechanisms involved in their maintenance and elimination, and outline hypotheses of the origin of Bs in this genus.

Highlights

Bchromosomes (Bs) are supernumerary, dispensable chromosomes that have been observed in all major groups of living organisms—animals, plants, and fungi [1]
In the genus Sorghum, Bs have been reported in five species: S. bicolor ssp. verticilliflorum [51], S. stipoideum (Figure 1a) [52], S. purpureosericeum (Figure 1b) [53,54], S. halepense (Figure 1c) [55,56], and S. nitidum (Figure 1d) [31,57]
PhyML analysis of concatenated sequences of ITS1-ITS2, trnH-psbA, and trnL-trnF resulted in a phylogram in which two strongly supported major clades I and II were identified (Figure 4), which is in agreeclose relationship between S. macrospermum and S. laxiflorum led to proposals to merge the Chaetosorghum and Heterosorghum sections [80,81,82]

Summary

Introduction

Bchromosomes (Bs) are supernumerary, dispensable chromosomes that have been observed in all major groups of living organisms—animals, plants, and fungi [1]. Bs seem to successfully persist in the populations thanks to their specific accumulation mechanisms [18] One of these mechanisms is nondisjunction, which has been relatively well described in rye and maize [12,19,20,21,22]. Genes localized on Bs were shown to play a role in female sex determination in cichlid fish [49], in the processes related to cell division in E. plorans [48], and in the cell cycle and development in the red fox (Vulpes vulpes) and raccoon dog (Nyctereutes procyonoides procyonoides) [50] These data suggest that Bs can carry genes controlling their specific behavior

B Chromosomes in the Genus Sorghum

Elimination and Maintenance of B Chromosomes

Did B Chromosomes Emerge Several Times in the Genus Sorghum?

Conclusions