1 Introduction

Genome size variation is a fundamental aspect of plant biology, reflecting the dynamic nature of genomes over evolutionary time. The DNA content of eukaryotic nuclei, often referred to as the C-value, can vary dramatically among species, with differences largely attributed to the repetitive fraction of the genome, including transposable elements (Hawkins et al., 2006). This variation is not merely a curiosity but has significant implications for understanding the evolutionary processes that shape genomes. For instance, the accumulation of long-terminal-repeat (LTR) retrotransposons has been shown to contribute significantly to genome size expansion in various plant lineages (Huang et al., 2020). Moreover, genome size can influence various biological traits, including cell size, growth rates, and adaptation to environmental conditions (Trávnícek et al., 2019).

The genus Gossypium, which includes economically important cotton species, presents a unique opportunity to study genome size variation and its evolutionary implications. Gossypium species exhibit a wide range of genome sizes, from approximately 880 Mb to 2 460 Mb, which is primarily due to the differential amplification of transposable elements (Hawkins et al., 2006). Understanding the genome size variation in Gossypium is crucial for several reasons. Firstly, it provides insights into the mechanisms of genome evolution, such as the role of transposable elements and structural rearrangements (Udall et al., 2019). Secondly, it helps in resolving phylogenetic relationships and the evolutionary history of cotton species, which is essential for cotton breeding and genetic improvement (Huang et al., 2020). Lastly, studying genome size variation can reveal how different Gossypium species have adapted to their environments, offering clues about the adaptive significance of genome size.

This study aims to provide a comprehensive overview of genome size variation in Gossypium and its evolutionary implications. This study summarizes the current knowledge on the extent and causes of genome size variation in Gossypium, with a focus on the role of transposable elements and structural changes, explores the evolutionary history of Gossypium species, including the origins and divergence of different genome types, and the impact of polyploidy on genome evolution; examines the adaptive significance of genome size variation in Gossypium, considering factors such as environmental adaptation and species-specific traits and identify gaps in the current understanding and suggest directions for future research in the field of plant genome evolution.

2 Gossypium: An Overview

2.1 Taxonomy and classification

The genus Gossypium, commonly known as cotton, is a member of the Malvaceae family and is classified into eight diploid genomic groups (A-G and K) and one allotetraploid genomic group (AD) (Chen et al., 2017a; Chen et al., 2017b). The diploid species have a base chromosome number of 13, while the allotetraploid species have 26 chromosomes, resulting from hybridization events between A and D genome species. Gossypium raimondii (D5) and G. arboreum (A2) are considered the progenitors of the economically significant allotetraploid species G. hirsutum (AD1) and G. barbadense (AD2) (Wang et al., 2018).

2.2 Geographical distribution

Gossypium species are distributed across tropical and subtropical regions worldwide. The genus is native to both the Old World (Africa and Asia) and the New World (Americas) (Udall et al., 2019). For instance, Gossypioides kirkii, a close relative of Gossypium, is found in East Africa and Madagascar, while Gossypium species themselves are widely cultivated in regions such as the United States, India, China, and Brazil (Chen et al., 2017a). The geographical distribution of Gossypium has significant implications for its genetic diversity and evolutionary history, with different species adapting to various environmental conditions.

2.3 Economic importance

Gossypium species, particularly G. hirsutum and G. barbadense, are of immense economic importance due to their production of natural textile fibers. These fibers are a primary raw material for the global textile industry, making cotton one of the most valuable agricultural commodities (Wang et al., 2018). The economic significance of cotton extends beyond fiber production; cottonseed oil and meal are also important by-products used in food and feed industries (Wang et al., 2018). The domestication and breeding of Gossypium species have led to significant improvements in fiber quality and yield, driven by both natural and artificial selection pressures (Miller, 2018).

3 Genome Size Variation in Gossypium

3.1 Methods for estimating genome size

Estimating genome size in Gossypium species has primarily been conducted using flow cytometry, a technique that measures the fluorescence of stained nuclei to determine DNA content. In a study by Hendrix and Stewart (2005), flow cytometry was used to measure the fluorescence of isolated Gossypium nuclei stained with propidium iodide. The fluorescence values were then converted to DNA content estimates based on the nuclear fluorescence of standard genotypes of barley, corn, and rice. This method allowed for the generation of revised DNA content estimates for 37 Gossypium species using best-standard practices. Additionally, Feulgen cytophotometry has been employed to reveal the mean value of DNA content for various Gossypium genomes, providing insights into the relationship between genomic chromosome size and DNA content.

3.2 Reported genome sizes across different species

The genome sizes of Gossypium species exhibit significant variation. For instance, the DNA content of diploid Gossypium species ranges from 880 Mb in G. raimondii to 2 460 Mb in other species (Hawkins et al., 2006). Another study reported a three-fold variation in DNA content estimates for Gossypium species, with the allopolyploid AD-genome size being nearly the additive of its progenitor genomes (Hendrix and Stewart, 2005). The genome sizes of Gossypium species have been reported as follows: D genome=10.95 pg, B genome=13.88 pg, F genome=14.31 pg, E genome=18.24 pg, A genome=18.66 pg, and C genome=20.30 pg. These variations are attributed to the differential accumulation of transposable elements and other repetitive DNA sequences (Huang et al., 2020).

3.3 Patterns of genome size variation within the genus

Genome size variation within the genus Gossypium is influenced by several factors, including the amplification of transposable elements and structural rearrangements. Differential lineage-specific expansion of various families of transposable elements has been observed among different Gossypium species. For example, Copia-like retrotransposable elements have accumulated in G. raimondii, while gypsy-like sequences have proliferated in species with larger genomes (Hawkins et al., 2006). Additionally, the formation of allotetraploids and subsequent speciation events have contributed to genome size variation. The A-genomes of Gossypium herbaceum and Gossypium arboreum evolved independently, with no ancestor-progeny relationship, and experienced genome size expansion due to long-terminal-repeat bursts (Huang et al., 2020). Furthermore, structural rearrangements, such as chromosome fusions and inversions, have played a role in genome size variation, as seen in the comparison between Gossypioides kirkii and Gossypium diploids (Udall et al., 2019). Genome size variation in Gossypium is a complex phenomenon driven by the amplification of transposable elements, structural rearrangements, and the formation of allotetraploids. These factors have led to significant differences in genome sizes across species and within the genus, providing valuable insights into the evolutionary dynamics of Gossypium genomes.

4 Mechanisms of Genome Size Evolution

4.1 Polyploidy and its impact on genome size

Polyploidy, the condition of having more than two complete sets of chromosomes, is a significant driver of genome size evolution in Gossypium. Polyploidy events have been recurrent in the evolutionary history of Gossypium, leading to substantial increases in genome size. For instance, an abrupt five- to sixfold ploidy increase approximately 60 million years ago, followed by allopolyploidy events around 1~2 million years ago, resulted in a 30-36-fold duplication of ancestral angiosperm genes in elite cottons like Gossypium hirsutum and Gossypium barbadense (Paterson et al., 2012). These polyploidization events have not only increased genome size but also contributed to the genetic complexity and phenotypic innovations observed in polyploid cotton species (Senchina et al., 2003).

4.2 Role of transposable elements

Transposable elements (TEs) play a crucial role in the variation of genome size in Gossypium. TEs, particularly long terminal repeat (LTR) retrotransposons, have differentially accumulated in various Gossypium species, leading to significant genome size differences. For example, Copia-like retrotransposons have proliferated in Gossypium raimondii, which has a smaller genome, while gypsy-like retrotransposons have expanded in species with larger genomes (Hawkins et al., 2006). The differential amplification of these TEs among lineages has been a major factor in genome size evolution, with specific subfamilies of retrotransposons undergoing lineage-specific expansions (Lin et al., 2011). This dynamic activity of TEs contributes to the overall genomic architecture and size variation observed in Gossypium species.

4.3 Gene duplication and loss

Gene duplication and loss are fundamental mechanisms influencing genome size in Gossypium. Polyploidy events often result in extensive gene duplication, which can lead to increased genome size. However, subsequent gene loss can counterbalance this effect. In Gossypium, nonreciprocal DNA exchanges between homeologous chromosomes have been observed, leading to gene conversion events that can result in gene loss or duplication (Guo et al., 2014). These homeologous gene conversion events (HeGCEs) are more frequent in certain genomic regions and can influence the dosage of specific alleles, contributing to the dynamic nature of the genome (Guo et al., 2014). Additionally, ancient polyploidization events have been suggested to predate the divergence of A- and D-genome progenitors, indicating a long history of gene duplication and loss in the evolution of Gossypium genomes (Rong et al., 2004; Paterson et al., 2012).

4.4 DNA loss mechanisms

DNA loss mechanisms are essential in maintaining genome size equilibrium in the face of TE proliferation and gene duplication. Rapid DNA loss acts as a counterbalance to the accumulation of retrotransposons, preventing unchecked genome expansion. In Gossypium, mechanisms such as unequal crossing over, illegitimate recombination, and deletion events contribute to the removal of excess DNA, including TEs. These DNA loss processes are crucial for stabilizing genome size and ensuring the proper functioning of the genome. The interplay between DNA gain through TE activity and DNA loss through various mechanisms shapes the overall genome size and structure in Gossypium.

5 Comparative Genomics in Gossypium

5.1 Comparative analysis of genome structure and content

Comparative genomics in Gossypium has revealed significant insights into the structure and content of its genomes. The genome sizes among Gossypium species vary considerably, primarily due to the differential amplification of transposable elements. For instance, the smallest genome, G. raimondii, has accumulated Copia-like retrotransposable elements, whereas larger genomes have seen a proliferation of gypsy-like sequences (Hawkins et al., 2006). This variation in genome size is also reflected in the AdhA region, where differential accumulation of retroelements and biased deletions have contributed to the size differences between diploid progenitors (Grover et al., 2007). Additionally, the physical composition and organization of Gossypium genomes show that repetitive DNA fractions play a significant role in genome size variation, with a notable correspondence in the location of centromeres across subgenomes and species (Lin and Paterson, 2009).

5.2 Synteny and collinearity among Gossypium species

Synteny and collinearity analyses among Gossypium species have demonstrated a high degree of conservation in genomic regions despite the differences in genome size. For example, the CesA region in two cotton genomes that diverged 5~10 million years ago shows extensive local conservation of genic and intergenic regions (Grover et al., 2007). Furthermore, genetic mapping studies have revealed that both diploid and tetraploid cottons exhibit negative crossover interference, with no major structural changes between Dt and D chromosomes, but with confirmed reciprocal translocations and several inversions between At chromosomes (Rong et al., 2004). These findings suggest that while there are structural rearrangements, the overall synteny and collinearity are maintained across Gossypium species.

5.3 Evolutionary relationships and divergence times

The evolutionary relationships and divergence times within the Gossypium genus have been elucidated through various genomic studies. The divergence of diploid and allotetraploid Gossypium species is marked by rapid evolutionary changes in mitochondrial genomes, with significant structural variations caused by repeat sequences leading to major inversions and translocations (Chen et al., 2017b). Additionally, genome comparisons between Gossypium and its relatives, such as Gossypioides kirkii, indicate that structural rearrangements, including chromosome fusions and inversions, have played a crucial role in the evolutionary history of these species (Udall et al., 2019). The divergence times of Gossypium species are estimated to be around 5~10 million years ago, with evidence suggesting that ancient polyploidization events predated the A-D divergence (Rong et al., 2004; Lin et al., 2011). These evolutionary insights are further supported by the differential abundance of repetitive elements in wild and domesticated accessions, highlighting the impact of both natural and artificial selection on genome size evolution (Miller, 2018).

6 Functional Implications of Genome Size Variation

6.1 Correlation between genome size and phenotypic traits

Genome size variation in Gossypium has been shown to correlate with various phenotypic traits. For instance, the accumulation of specific transposable elements, such as gypsy-like retrotransposons, has been linked to genome size expansion in certain Gossypium species, which in turn may influence phenotypic traits such as fiber quality and productivity (Hawkins et al., 2006; Paterson et al., 2012). Additionally, studies on other plant species have demonstrated that genome size reduction can lead to rapid phenotypic evolution, enhancing traits like early growth rate and stem elongation, which could be relevant for understanding similar processes in Gossypium (Lavergne et al., 2010).

6.2 Impact on plant growth and development

The impact of genome size on plant growth and development in Gossypium is multifaceted. Polyploidy, which results in increased genome size, has been associated with enhanced fiber productivity and quality in tetraploid cottons compared to their diploid counterparts (Paterson et al., 2012). This suggests that larger genome sizes may confer advantages in terms of growth and development, potentially through the duplication of genes involved in these processes. Furthermore, the differential accumulation of transposable elements in Gossypium species with varying genome sizes indicates that these elements may play a role in regulating genes critical for growth and development (Hawkins et al., 2006; Hawkins et al., 2008).

6.3 Adaptation to environmental stressors

Genome size variation in Gossypium also appears to play a role in adaptation to environmental stressors. The accumulation of specific transposable elements, such as the gypsy-like retrotransposon Gorge3, has been linked to genome size changes and may contribute to the ability of Gossypium species to adapt to different environmental conditions (Senchina et al., 2003; Hawkins et al., 2006). Additionally, the study of invasive species has shown that genome size reduction can enhance traits that improve invasive potential, such as higher early growth rates, which could be relevant for understanding how Gossypium species adapt to new environments (Lavergne et al., 2010). The evolutionary dynamics of genome size variation, including the role of polyploidy and transposable elements, provide insights into how Gossypium species may respond to environmental challenges (Paterson et al., 2012).

7 Evolutionary Significance of Genome Size Variation

7.1 Genome size and speciation

Genome size variation in Gossypium has significant implications for speciation. The differential amplification of transposable elements (TEs) among Gossypium species is a key driver of genome size variation, which in turn influences speciation. For instance, the accumulation of Copia-like retrotransposons in G. raimondii and gypsy-like sequences in other lineages has led to substantial genome size differences, which may contribute to reproductive isolation and speciation (Hawkins et al., 2006). Additionally, the independent evolution of A-genomes from a common ancestor and the subsequent speciation events highlight the role of genome size changes in the diversification of Gossypium species (Huang et al., 2020). The structural variations and recombination rates observed between diploid and tetraploid genomes further underscore the importance of genome size in the evolutionary trajectory of Gossypium (Desai et al., 2006).

7.2 Role in hybridization and polyploidy events

Polyploidy, a common phenomenon in Gossypium, is closely linked to genome size variation. The formation of allotetraploid cotton approximately 1.5 million years ago involved the merging of divergent genomes, leading to a significant increase in genome size and genetic complexity (Senchina et al., 2003; Paterson et al., 2012). This polyploidization event has been associated with enhanced fiber productivity and quality, demonstrating the adaptive advantages conferred by increased genome size. Moreover, the extensive nonreciprocal DNA exchanges between homeologous chromosomes in tetraploid cottons have shaped the nascent polyploid genome, further contributing to genome size variation and the evolutionary success of polyploid species (Guo et al., 2014). The role of repetitive DNA elements in genome size expansion during polyploidization events is also evident, as seen in the differential abundance of repetitive content in domesticated versus wild accessions of G. hirsutum (Miller, 2018).

7.3 Genome size as an adaptive trait

Genome size variation in Gossypium is not merely a byproduct of evolutionary processes but also an adaptive trait. The correlation between genome size and environmental factors suggests that natural selection acts on genome size to optimize physiological and ecological performance (Miller, 2018, https://doi.org/10.31274/ETD-180810-6044). For example, the large-scale replication of repetitive DNA in certain Gossypium genomes has been linked to adaptive traits such as fiber quality and yield, which are crucial for the plant’s survival and reproductive success. The adaptive significance of genome size is further supported by the observation that genome size differences between wild and domesticated accessions of G. hirsutum are associated with changes in repetitive element content, indicating that artificial selection has also played a role in shaping genome size. The conserved locations of centromeres and the correspondence of physical and genetic distances across subgenomes and species highlight the functional importance of genome size in maintaining genomic stability and facilitating adaptation (Lin and Paterson, 2009).

8 Technological Advances and Future Directions

8.1 Advances in sequencing technologies and their impact

Recent advancements in sequencing technologies have significantly enhanced our understanding of genome size variation in Gossypium. The integration of single-molecule real-time sequencing, BioNano optical mapping, and high-throughput chromosome conformation capture techniques has led to the development of high-quality reference genome assemblies for Gossypium species such as G. hirsutum and G. barbadense (Wang et al., 2018). These technologies have improved the contiguity and completeness of genome assemblies, particularly in regions with high repeat content, such as centromeres. Additionally, the use of PacBio, Bionano, and Hi-C technologies has facilitated the generation of high-quality genome sequences for species like Gossypioides kirkii, enabling detailed comparisons with Gossypium genomes and the identification of structural rearrangements (Udall et al., 2019). These advancements have provided deeper insights into the evolutionary dynamics of genome size variation and the role of repetitive elements in shaping genome architecture.

8.2 Emerging trends in genome size research

Emerging trends in genome size research in Gossypium include the study of transposable elements and their lineage-specific amplification, which has been identified as a major driver of genome size variation. For instance, differential accumulation of Copia-like and gypsy-like retrotransposable elements has been observed among Gossypium species, contributing to significant differences in genome sizes (Hawkins et al., 2006). Another trend is the investigation of genome-specific repetitive elements, such as the ICRd motif, which plays a crucial role in genome variation between the A and D genomes of Gossypium (Lu et al., 2019). Additionally, the study of intraspecific variation in genome size between wild and domesticated accessions has provided insights into the evolutionary forces acting on genome size over short time scales (Miller, 2018, https://doi.org/10.31274/ETD-180810-6044). These trends highlight the importance of repetitive elements and structural variations in understanding genome size evolution.

8.3 Future research prospects and challenges

Future research in the field of genome size variation in Gossypium will likely focus on several key areas. One important direction is the continued improvement of genome assemblies for various Gossypium species, which will facilitate more comprehensive comparative genomics studies and the identification of structural variations that contribute to genome size differences (Li et al., 2014; Huang et al., 2020). Another promising area is the exploration of the functional implications of genome size variation, particularly in relation to traits such as fiber quality and disease resistance. The identification of quantitative trait loci (QTL) associated with these traits will be crucial for breeding programs aimed at improving cotton varieties (Wang et al., 2018).

However, several challenges remain. One major challenge is the accurate annotation of repetitive elements and the determination of their evolutionary dynamics. The high abundance and diversity of repetitive sequences in Gossypium genomes complicate their annotation and functional characterization (Lin and Paterson, 2009). Additionally, understanding the mechanisms underlying the differential amplification of transposable elements and their impact on genome size will require further investigation (Hawkins et al., 2006). Addressing these challenges will be essential for advancing our knowledge of genome size evolution and its implications for the biology and improvement of Gossypium species. The integration of advanced sequencing technologies, the study of repetitive elements, and the exploration of intraspecific variation are driving progress in understanding genome size variation in Gossypium. Future research will need to address the challenges of repetitive element annotation and functional characterization to fully elucidate the evolutionary and practical implications of genome size variation in this important genus.

9 Concluding Remarks

Genome size variation in Gossypium is primarily driven by the differential amplification of transposable elements, particularly retrotransposons. Studies have shown that Copia-like retrotransposons have accumulated in species with smaller genomes, such as G. raimondii, while gypsy-like retrotransposons have proliferated in species with larger genomes. The genome sequences of Gossypium herbaceum, Gossypium arboreum, and Gossypium hirsutum have provided insights into the evolutionary history and phylogenetic relationships within the genus, indicating that genome size expansion is linked to long-terminal-repeat bursts. Additionally, the nuclear DNA content of Gossypium species reveals a threefold variation, with both increases and decreases in genome size observed across different species. Comparative genomics has identified structural variations, such as chromosome fusions and inversions, contributing to genome size differences.

The findings on genome size variation in Gossypium have significant implications for future research and breeding programs. Understanding the role of transposable elements in genome size evolution can inform strategies to manipulate genome size for crop improvement. For instance, targeting specific retrotransposon families could potentially reduce genome size and enhance desirable traits. The high-quality genome assemblies and genetic maps of Gossypium species provide valuable resources for identifying quantitative trait loci (QTLs) associated with fiber quality and other agronomic traits. Future research should focus on exploring the functional impact of genome size variation on gene expression and phenotypic diversity, as well as the mechanisms underlying the differential amplification of transposable elements.

Genome size variation in Gossypium is a complex and dynamic process influenced by multiple evolutionary forces, including transposable element activity, structural rearrangements, and polyploidization events. The differential accumulation of retrotransposons and structural variations has played a crucial role in shaping the genomic architecture of Gossypium species. This variation has not only contributed to the diversification of the genus but also provided a rich source of genetic material for adaptation and evolution. The study of genome size variation in Gossypium offers valuable insights into the broader mechanisms of genome evolution in plants and highlights the importance of repetitive DNA elements in driving genomic diversity. Understanding these processes is essential for harnessing the genetic potential of Gossypium for crop improvement and sustainable agriculture.

Acknowledgments

We appreciate the feedback from two anonymous peer reviewers on the manuscript of this study, whose careful evaluation and constructive suggestions have contributed to the improvement of the manuscript.

Conflict of Interest Disclosure

The authors affirm that this research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest.

Reference

Chen Z., Nie H., Grover C., Wang Y., Li P., Wang M., Pei H., Zhao Y., Li S., Wendel J., and Hua J., 2017a, Entire nucleotide sequences of Gossypium raimondii and G. arboreum mitochondrial genomes revealed A-genome species as cytoplasmic donor of the allotetraploid species, Plant Biology, 19(3): 484-493.

https://doi.org/10.1111/plb.12536

Chen Z., Nie H., Wang Y., Pei H., Li S., Zhang L., and Hua J., 2017b, Rapid evolutionary divergence of diploid and allotetraploid Gossypium mitochondrial genomes, BMC Genomics, 18(1): 876.

https://doi.org/10.1186/s12864-017-4282-5

Desai A., Chee P., Rong J., May O., and Paterson A., 2006, Chromosome structural changes in diploid and tetraploid A genomes of Gossypium, Genome, 49(4): 336-345.

https://doi.org/10.1139/G05-116

Grover C., Kim H., Wing R., Paterson A., and Wendel J., 2007, Microcolinearity and genome evolution in the AdhA region of diploid and polyploid cotton (Gossypium), The Plant Journal, 50(6): 995-1006.

https://doi.org/10.1111/J.1365-313X.2007.03102.X

Guo H., Wang X., Gundlach H., Mayer K., Peterson D., Scheffler B., Chee P., and Paterson A., 2014, Extensive and biased intergenomic nonreciprocal DNA exchanges shaped a nascent polyploid genome, Gossypium (cotton), Genetics, 197(4): 1153-1163.

https://doi.org/10.1534/genetics.114.166124

Hawkins J., Hu G., Rapp R., Grafenberg J., and Wendel J., 2008, Phylogenetic determination of the pace of transposable element proliferation in plants: copia and LINE-like elements in Gossypium, Genome, 51(1): 11-18.

https://doi.org/10.1139/g07-099

Hawkins J., Kim H., Nason J., Wing R., and Wendel J., 2006, Differential lineage-specific amplification of transposable elements is responsible for genome size variation in Gossypium, Genome Research, 16: 1252-1261.

https://doi.org/10.1101/GR.5282906

Hendrix B., and Stewart J., 2005, Estimation of the nuclear DNA content of Gossypium species, Annals of Botany, 95(5): 789-797.

https://doi.org/10.1093/AOB/MCI078

Huang G., Wu Z., Percy R., Bai M., Li Y., Frelichowski J., Hu J., Wang K., Yu J., and Zhu Y., 2020, Genome sequence of Gossypium herbaceum and genome updates of Gossypium arboreum and Gossypium hirsutum provide insights into cotton A-genome evolution, Nature Genetics, 52(5): 516-524.

https://doi.org/10.1038/s41588-020-0607-4

Lavergne S., Muenke N., and Molofsky J., 2010, Genome size reduction can trigger rapid phenotypic evolution in invasive plants, Annals of Botany, 105(1): 109-116.

https://doi.org/10.1093/aob/mcp271

Li F., Fan G., Wang K., Sun F., Yuan Y., Song G., Li Q., Ma Z., Lu C., Zou C., Chen W., Liang X., Shang H., Liu W., Shi C., Xiao G., Gou C., Ye W., Xu X., Zhang X., Wei H., Li Z., Zhang G., Wang J., Liu K., Kohel R., Percy R., Yu J., Zhu Y., Wang J., and Yu S., 2014, Genome sequence of the cultivated cotton Gossypium arboreum, Nature Genetics, 46(6): 567-572.

https://doi.org/10.1038/ng.2987

Lin L., and Paterson A., 2009, Physical composition and organization of the Gossypium genomes, In: Paterson A.H. (ed.), Genetics and genomics of cotton, Springer, New York, USA, pp.141-155.

https://doi.org/10.1007/978-0-387-70810-2_6

Lin L., Tang H., Compton R., Lemke C., Rainville L., Wang X., Rong J., Rana M., and Paterson A., 2011, Comparative analysis of Gossypium and Vitis genomes indicates genome duplication specific to the Gossypium lineage, Genomics, 97(5): 313-320.

https://doi.org/10.1016/j.ygeno.2011.02.007

Lu H., Cui X., Zhao Y., Magwang R., Li P., Cai X., Zhou Z., Wang X., Liu Y., Xu Y., Hou Y., Peng R., Wang K., and Liu F., 2019, Identification of a genome-specific repetitive element in the Gossypium D genome, Plant Biology, 8: e8344.

https://doi.org/10.7717/peerj.8344

Paterson A., Wendel J., Gundlach H., Guo H., Jenkins J., Jin D., Llewellyn D., Showmaker K., Shu S., Udall J., Yoo M., Byers R., Chen W., Doron-Faigenboim A., Duke M., Gong L., Grimwood J., Grover C., Grupp K., Hu G., Lee T., Li J., Lin L., Liu T., Marler B., Page J., Roberts A., Romanel E., Sanders W., Szadkowski E., Tan X., Tang H., Xu C., Wang J., Wang Z., Zhang D., Zhang L., Ashrafi H., Bedon F., Bowers J., Brubaker C., Chee P., Das S., Gingle A., Haigler C., Harker D., Hoffmann L., Hovav R., Jones D., Lemke C., Mansoor S., Rahman M., Rainville L., Rambani A., Reddy U., Rong J., Saranga Y., Scheffler B., Scheffler J., Stelly D., Triplett B., Deynze A., Vaslin M., Waghmare V., Walford S., Wright R., Zaki E., Zhang T., Dennis E., Mayer K., Peterson D., Rokhsar D., Wang X., and Schmutz J., 2012, Repeated polyploidization of Gossypium genomes and the evolution of spinnable cotton fibres, Nature, 492: 423-427.

https://doi.org/10.1038/nature11798

Rong J., Abbey C., Bowers J., Brubaker C., Chang C., Chee P., Delmonte T., Ding X., Garza J., Marler B., Park C., Pierce G., Rainey K., Rastogi V., Schulze S., Trolinder N., Wendel J., Wilkins T., Williams-Coplin T., Wing R., Wright R., Zhao X., Zhu L., and Paterson A., 2004, A 3347-locus genetic recombination map of sequence-tagged sites reveals features of genome organization, transmission and evolution of cotton (Gossypium), Genetics, 166(1): 389-417.

https://doi.org/10.1534/genetics.166.1.389

Senchina D., Álvarez I., Cronn R., Liu B., Rong J., Noyes R., Paterson A., Wing R., Wilkins T., and Wendel J., 2003, Rate variation among nuclear genes and the age of polyploidy in Gossypium, Molecular Biology and Evolution, 20(4): 633-643.

https://doi.org/10.1093/MOLBEV/MSG065

Trávnícek P., Čertner M., Ponert J., Chumová Z., Jersáková J., and Suda J., 2019, Diversity in genome size and GC content shows adaptive potential in orchids and is closely linked to partial endoreplication, plant life-history traits and climatic conditions, The New Phytologist, 224(4): 1642-1656.

https://doi.org/10.1111/nph.15996

Udall J., Long E., Ramaraj T., Conover J., Yuan D., Grover C., Gong L., Arick M., Masonbrink R., Peterson D., and Wendel J., 2019, The genome sequence of Gossypioides kirkii illustrates a descending dysploidy in plants, Frontiers in Plant Science, 10: 1541.

https://doi.org/10.3389/fpls.2019.01541

Wang M., Tu L., Yuan D., Zhu D., Shen C., Li J., Liu F., Pei L., Wang P., Zhao G., Ye Z., Huang H., Yan F., Ma Y., Zhang L., Liu M., You J., Yang Y., Liu Z., Huang F., Li B., Qiu P., Zhang Q., Zhu L., Jin S., Yang X., Min L., Li G., Chen L., Zheng H., Lindsey K., Lin Z., Udall J., and Zhang X., 2018, Reference genome sequences of two cultivated allotetraploid cottons, Gossypium hirsutum and Gossypium barbadense, Nature Genetics, 51(2): 224-229.

https://doi.org/10.1038/s41588-018-0282-x