Polyploidization and Genome Size Evolution in Australian Billy Buttons (<i>Craspedia</i>, Asteraceae: Gnaphalieae)

Castelli, Meghan A.; Miller, Cathy H.; Schmidt‐Lebuhn, Alexander N.

doi:10.1086/691460

Cited by 8 publications

(7 citation statements)

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“…Genome size is an important characteristic for a species that is related in part to the ploidy level, plant physiology, ecology and genome evolution (Heslop-Harrison 1995). Genome size studies of polyploids have contributed to improving the knowledge of the process of polyploid formation (Bures et al 2004;Poggio et al 2014;Castelli et al 2017). Many studies of other turfgrasses using laser flow cytometry have demonstrated that nuclear DNA content is closely correlated with chromosome number, and thus ploidy level (Johnson et al 1998;Eaton et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Variation in ploidy level and genome size of Cynodon dactylon (L.) Pers. along a latitudinal gradient

et al. 2019

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Knowledge of ploidy level and genome size in a germplasm collection is critical before studying genetic diversification of different environmental range in grasses and other plants. We assessed the geographic patterns in ploidy level and genome size of 216 individuals of Cynodon dactylon (L.) Pers. (common bermudagrass) by flow cytometry of accessions sampled from 16 geographic sites along a latitudinal gradient from 22°35′ N to 36°18′ N across China. Flow cytometry histograms combined with mitotic chromosome observations results show that tetraploids were the most frequent ploidy level, constituting 44.91% of all individuals. Nuclear DNA contents were 2.384, 2.419, 2.437, 2.873 and 3.288 pg/2C for the diploid, triploid, tetraploid, pentaploid and hexaploid, respectively. Higher proportions of polyploid individuals were observed within populations at the highest and lowest latitudes. In addition, monoploid genome size of C. dactylon progressively increased with increasing ploidy level. Temperature and precipitation had the influence on ploidy level for all the sites. The relationship between ploidy level and geographic distribution for C. dactylon will facilitate the utilization of this species for biological and genetic research.

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Section: Introductionmentioning

confidence: 99%

Variation in ploidy level and genome size of Cynodon dactylon (L.) Pers. along a latitudinal gradient

et al. 2019

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“…The hypothesis of a paleopolyploid origin of the Australasian clade (Smissen & al., 2011) and the observation that some genera represent polyploid complexes (Kokubugata & Holland, 2002;Castelli & al., 2017) suggest that paralogy should be expected, and our data showed paralogy in 176 genes. We resolved the issue by excluding the affected genes after preliminary analyses indicated that phylogenies produced using the other ortholog resolution approaches implemented by Yang & Smith (2014), which would have increased the number of available genes, did not provide notably better resolution and branch support (not shown).…”

Section: ■ Resultsmentioning

confidence: 99%

Phylogenomic data reveal four major clades of Australian Gnaphalieae (Asteraceae)

Schmidt‐Lebuhn

Bovill

2021

TAXON

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Within tribe Gnaphalieae (Asteraceae), the Australasian clade is one of the four major clades. In Australia, the Gnaphalieae account for 488 species or approximately half of the native Asteraceae, encompassing wide ecological and morphological diversity including shrubs, everlasting paper daisies, cudweeds, alpine cushion plants, and ephemeral herbs in the arid zone. The evolution of the Australasian clade is still poorly understood. The most detailed previous infratribal classification of Gnaphalieae has recently been revised, resulting in the recognition of two subtribes, with all Australian species placed in subtribe Gnaphaliinae. The most comprehensive previous phylogeny of Australian Gnaphalieae used high-copy ribosomal and chloroplast markers but showed limited resolution and branch support. We used conserved ortholog set data produced with sequence capture and 53 chloroplast genes to infer nuclear and chloroplast likelihood phylogenies for Australian Gnaphalieae, generating data for at least one species each from 80 of the 86 native genera. Four major clades were resolved: the Euchiton clade of cudweed-like and alpine perennial species; the shrubby Cassinia clade; the predominantly perennial and eastern Australian Waitzia clade; and the predominantly ephemeral and western Australian to Eremaean Angianthus clade. The Cassinia, Waitzia, and Angianthus clades are largely congruent with "groups" in a previous morphological analysis and classification of Gnaphalieae. Analysis of ancestral ranges implied the temperate Southeast of Australia as the most likely area of origin for the Australian Gnaphalieae as a whole and for three of the four major clades. The Angianthus clade was implied to be ancestrally Eremaean, with a major secondary radiation originating in southwestern Australia. Our broadly sampled phylogeny provides a framework to inform sampling and design of future studies to test the circumscription of genera.

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“…Fresh leaf material was collected from living specimens and kept on ice. A single triploid clone of Bellis perennis L. (2C = 3.41 pg DNA) was used as a standard (Castelli, Miller, & Schmidt‐Lebuhn, ). Approximately 50 mg of Rutidosis lanata and 10 mg of standard leaf material were each placed in 1,200 μl of ice‐cold Modified Galbraith's buffer (Galbraith et al., ; Price, ) [4.58 g MgCl2, 2.1 g MOPSO, 4.44 g Citric Acid, 15.0 g PVP‐10, 0.5 ml Triton X‐100, 2.5 ml Tween 20, made up to 500 ml with distilled water.…”

Section: Methodsmentioning

confidence: 99%

Genetic rescue in a plant polyploid complex: Case study on the importance of genetic and trait data for conservation management

Schmidt‐Lebuhn

Marshall

Dreis³

et al. 2018

Ecology and Evolution

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Knowledge of the biology of rare plant species is indispensable to aid their survival and to inform efficient conservation actions, but in many cases relevant data are lacking. In addition, while studies of conservation genetics have provided a wealth of information on the considerations arising from inbreeding, mate limitation, or local adaptation, the impact of intraspecific polyploidy remains understudied. In this study, we examined the breeding system of the rare Australian daisy Rutidosis lanata (Asteraceae) and screened ten of its populations for their ploidy level to develop recommendations for management actions, in particular, with regard to seed sourcing and genetic rescue. We found R. lanata to represent a polyploid complex, with tetraploid, pentaploid and hexaploid individuals coexisting in the same species. Crossing experiments confirmed R. lanata to be self‐incompatible. Mate availability varied from c. 49% to c. 76% across populations. Most populations showed mate availability of c. 50%–70%, suggesting that mate limitation resulting from a lack of local genetic diversity may cause or at least contribute to reduced seed set. Crossing between populations resulted in significantly higher reproductive success for all populations except one, suggesting the possibility of genetic rescue through population mixing. However, the crossing experiments also showed that pentaploids suffer from a severely reduced paternal reproductive fitness. Any additional hybrids between tetraploids and pentaploids, as would be created by mixing populations with different genome copy numbers during conservation work, would consequently exacerbate mate limitation and thus reduce population viability. We conclude that seed set and thus population viability can be maximized by mixing populations with the same number of genome copies, but that populations with different numbers should be kept spatially separated. The case of Rutidosis lanata provides an example and a potential template for examining the conservation genetics of other species that may constitute polyploid complexes.

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Polyploidization and Genome Size Evolution in Australian Billy Buttons (Craspedia, Asteraceae: Gnaphalieae)

Cited by 8 publications

References 50 publications

Variation in ploidy level and genome size of Cynodon dactylon (L.) Pers. along a latitudinal gradient

Variation in ploidy level and genome size of Cynodon dactylon (L.) Pers. along a latitudinal gradient

Phylogenomic data reveal four major clades of Australian Gnaphalieae (Asteraceae)

Genetic rescue in a plant polyploid complex: Case study on the importance of genetic and trait data for conservation management

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