View Full Table | Close Full ViewTable 1.

Background information for the switchgrass accessions used in this study, including published chromosome numbers based on cytological data and ploidy determinations based solely on flow cytometry.

 
Accession Type Ecotype PI No. 2n or Ploidy Sample n Data source Authority
Blackwell C U Grif 16409 54 12 PMC (Riley and Vogel, 1982)
72 8 AMC,PMC (Hopkins et al., 1996)
72 3 RT (Lu et al., 1998)
4X,8X 3,18 FC (Narasimhamoorthy et al., 2008)
Carthage C U 421138 6X or 8X? 10 FC (Hultquist et al., 1996)
Cave-in-Rock C U 569228 72 7 AMC,PMC (Hopkins et al., 1996)
72 1 RT (Lu et al., 1998)
4X,6X,8X 1,3,18 FC (Narasimhamoorthy et al., 2008)
Dacotah C U 537588 36 20 MC (Barker et al., 1990)
4X 2 FC (Narasimhamoorthy et al., 2008)
Forestburg C U 478001 36 20 MC (Barker et al., 1988); Barker, personal communication, 2010
Kanlow C L 421521 36 7 PMC (Riley and Vogel, 1982)
36 1 AMC;PMC (Hopkins et al., 1996)
36 5 RT;PMC (Lu et al., 1998)
4X 2 FC (Narasimhamoorthy et al., 2008)
KY 1625 C U 431575 72 4 AMC;PMC (Hopkins et al., 1996)
36,54,72 9 n.i. (Henry and Taylor, 1989)
4X 2 FC (Narasimhamoorthy et al., 2008)
Pathfinder C U 642192 54 12 PMC (Riley and Vogel, 1982)
72 15 AMC; PMC (Hopkins et al., 1996)
Sunburst C U 598136 6X or 8X? 10 FC (Hultquist et al., 1996)
4X 2 FC (Narasimhamoorthy et al., 2008)
WS4U BP U 639191 4X 162 FC (Casler et al., 2006)
WS8U BP U 639192 8X 98 FC (Casler et al., 2006)
WS98-IP NP U n.i. (Casler et al., 2007)
C = cultivar; BP = breeding population; NP = natural population.
U = upland; L = lowland.
§Ploidy level shown if only flow cytometry data are given, without direct cytological evidence.
PMC = pollen mother cell; AMC = apical meristem cell; MC = meristematic cell (type not specified); RT = root tip; FC = flow cytometry (estimate of ploidy).
#n.i. = no information.



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Switchgrass accession survey (Experiment 1): Overall experimental means, standard errors (SE), and ranges of genome sizes (picograms of DNA), as measured by flow cytometry.

 
Ploidy Accession name N Mean SE Range (min-max)
4X WS98-IP 15 2.23 0.060 1.81–2.29
WS4U 14 2.27 0.052 1.95–2.66
Dacotah 15 2.37 0.051 2.01–2.77

Kanlow
15
2.51
0.024
2.36–2.68
8X Cave-in-Rock 14 4.75 0.123 3.89–5.43
Forestburg-E 15 4.77 0.090 4.23–5.24
Blackwell 15 4.80 0.082 4.15–5.14
Sunburst 15 4.83 0.090 4.19–5.39
Carthage-C 14 4.89 0.092 4.07–5.46
Forestburg-C 15 4.91 0.091 4.24–5.58
WS8U 15 4.92 0.095 4.36–5.84
Pathfinder 15 5.00 0.076 4.53–5.53
Carthage-E 5 5.27 0.197 4.68–5.85
For two cultivars (Carthage and Forestburg), two seed sources were used and measured separately. These are indicated by a “C,” in which case the source is the Casler germplasm collection; an “E” indicates that the source is Ernst Conservation seeds. For all others, the Casler germplasm collection is the source.
Single tetraploid Cave-in-Rock plant not included in the calculation of cultivar descriptive statistics.



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Analysis of variance of switchgrass cultivar genome size, as measured by flow cytometry. Type III sums of squares used in analysis. R2 for the model = 0.95. Significance levels are p < 0.0001 ****; p < 0.01**.

 
Source df MS F
Block 4 0.9093 11.54 ****
Ploidy 1 249.9104 3171.15 ****
Cultivar (Ploidy) 11 0.2099 2.66 **
Error 165



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Euploidy and aneuploidy in switchgrass (Experiment 3): Descriptive statistics for (A) all counts and (B) individual plants.

 
(A) All counts
Total n Euploid n Aneuploid n % Aneuploid Low aneuploid n High aneuploid n % Low Aneuploid
4X 56 43 13 23.2 7 6 53.8
8X 80 11 69 86.3 62 7 89.9
(B) By individual plants (with two or more counts)

Total n
100% Euploid
100% Aneuploid
Mixture of both
% with aneuploid cells
4X 10 5 0 5 50.0
8X 16 1 10 5 93.8



View Full Table | Close Full ViewTable 5.

Nuclear organization region-fluorescent in situ hybridization (NOR-FISH) results reveal ploidy-specific variation in chromosomal constitution. See images in Fig. 6, 7; Suppl. Figures 1, 2.

 
Ploidy 2n Cultivar ID Telomeric Interstitial Isotelomeric Images
4X 36 Dacotah DCH-2 2 pairs 0 0 Fig. 6, Suppl. Figure 1A, B
36 Dacotah DCH-15 2 pairs 0 0 Suppl. Figure 1C, D
36 WS4U W4U-13.2 2 pairs 0 0 Suppl. Figure 1E, F

36
WS4U
W4U-CL2
2 pairs
0
0
Suppl. Figure 1G, H
8X 72 WS8U W8U-2.1 1 3 6 Suppl. Figure 2A, B
70 WS8U W8U-6.1 0 4 3
70 Cave-in-Rock CIR-cl2.1 2 3 1 Suppl. Figure 2E, F
70 Pathfinder PFR-15.2 1 3 2
75 Sunburst SBT-cl1.2 1 2 7
74 Carthage CTE-19.1 0 4 7
72 Blackwell BWL-2.2 2 3 5 Fig. 7, Suppl. Figure 2C, D
Signals detected on the telomeres of both arms of isochromosomes.