Scaling Chromosomes for an Evolutionary Karyotype: A Chromosomal Tradeoff between Size and Number across Woody Species

Abstract

This study aims to examine the expected scaling relationships between chromosome size and number across woody species and to clarify the importance of the scaling for the maintenance of chromosome diversity by analyzing the scaling at the inter- & intra-chromosomal level. To achieve for the goals, chromosome trait data were extracted for 191 woody species (including 56 evergreen species and 135 deciduous species) from the available literature. Cross-species analyses revealed a tradeoff among chromosomes between chromosome size and number, demonstrating there is selective mechanism crossing chromosomes among woody species. And the explanations for the result were presented from intra- to inter-chromosome contexts that the scaling may be compromises among scale symmetry, mechanical requirements, and resource allocation across chromosomes. Therein, a 3/4 scaling pattern was observed between total chromosomes and m-chromosomes within nucleus which may imply total chromosomes may evolve from more to less. In addition, the primary evolutionary trend of karyotype and the role of m-chromosomes in the process of karyotype evolution were also discussed.

Molecular cytogenetic analysis of genome-specific repetitive elements in Citrus clementina Hort. Ex Tan. and its taxonomic implications

“…Karyotypes can yield valuable information regarding the highest level of structural and functional organization of chromosomes that are the main carriers of genetic material within the nuclei of each eukaryotic cell [13]. The more closely related species are, the more similar karyotypes they share [14].…”

Genome Size and Chromosome Number Relationship Contradicts the Principle of Darwinian Evolution from Common Ancestor

“…This indicated that the TCN may have evolved from more to less in woody plants because deciduous species had more m-chromosomes while evergreens had more total chromosomes number in their nuclei. The increase in TCN will trigger an increase in m-chromosomes at a 1.5-fold faster rate [13]. Increasing the number of m-chromosomes preserves karyotype symmetry which opposes the minimum interaction theory mentioned above.…”

“…It has been considered as an essential taxonomic and evolutionary criterion of living species [13][14][15][16]. The minimum interaction hypothesis of karyotype introduced by Imai et al [17] suggested that the karyotype usually tends to increase the number of acrocentric and reduce the formation of metacentric chromosomes (m-chromosomes) [17,18].…”

Integrated Karyotypes of Diploid and Tetraploid Carrizo Citrange (Citrus sinensis L. Osbeck × Poncirus trifoliata L. Raf.) as Determined by Sequential Multicolor Fluorescence in situ Hybridization With Tandemly Repeated DNA Sequences

“…Each species has a characteristic chromosome complement, the karyotype (Jiang, 2019), which represents the highest level of structural and functional organization of genome (Weiss-Schneeweiss and Schneeweiss, 2013; Liang and Chen, 2015). Karyotypic features have greatly facilitated taxonomic and systematic studies, and they have also provided important insight into genome size estimations as well as genome structure and organization at the chromosomal level in numerous plant species (Chèvre et al, 2018), including radish (Raphanus sativus L.) (He et al, 2015), Coix lacryma-jobi L. and Coix aquatica Roxb.…”

“…(Deng et al, 2019a). Elucidating chromosome constitution and the karyotype including the number, absolute and relative size, symmetry, and centromere position of the chromosome complement in nucleus cell of individual eukaryotic species, is a fundamental question in plant biology (Liang and Chen, 2015;Jiang, 2019). Nevertheless, up to now, the chromosomal characterization of CC rootstock remains unexplored, partly because of its inherent small size and morphological similarity of mitotic chromosomes as well as the paucity of accessible chromosome landmarks in the Aurantioideae subfamily (Krug, 1943;Silva et al, 2015).…”