Table 2. Open in new tab Information on...

Species	No. of chromosomes (2n)	No. of 18S/5S rDNA sites at metaphase^a	Estimated length of 35S/5S rDNA contigs (bp)	Estimated GP (%)/CN of 18S rDNA^b	Estimated GP (%)/CN of 5S rDNA^b
Ephedra altissima	28^e	14–16	6766	0.058/6000	0.060/6200	0.010/15000	0.005/7700
Gnetum montanum	44^f	~6–8/>10	6527/627	0.132/3100	0.142/4000	0.301/105200	0.250/87400
Welwitschia mirabilis	42^g	2/2	5981/958	0.063/2500	n.d.^h	0.007/3800	n.d.^h

Species	No. of chromosomes (2n)	No. of 18S/5S rDNA sites at metaphase^a	Estimated length of 35S/5S rDNA contigs (bp)	Estimated GP (%)/CN of 18S rDNA^b	Estimated GP (%)/CN of 5S rDNA^b
Ephedra altissima	28^e	14–16	6766	0.058/6000	0.060/6200	0.010/15000	0.005/7700
Gnetum montanum	44^f	~6–8/>10	6527/627	0.132/3100	0.142/4000	0.301/105200	0.250/87400
Welwitschia mirabilis	42^g	2/2	5981/958	0.063/2500	n.d.^h	0.007/3800	n.d.^h

Table 2.

Information on chromosome numbers (2n) and rDNA characterization in the three gnetophyte species analysed

Species	No. of chromosomes (2n)	No. of 18S/5S rDNA sites at metaphase^a	Estimated length of 35S/5S rDNA contigs (bp)	Estimated GP (%)/CN of 18S rDNA^b		Estimated GP (%)/CN of 5S rDNA^b
Species	No. of chromosomes (2n)	No. of 18S/5S rDNA sites at metaphase^a	Estimated length of 35S/5S rDNA contigs (bp)	Calculated from HTP^c	Slot-blot hybridization^d	Calculated from HTP^c	Slot-blot hybridization^d
Ephedra altissima	28^e	14–16	6766	0.058/6000	0.060/6200	0.010/15000	0.005/7700
Gnetum montanum	44^f	~6–8/>10	6527/627	0.132/3100	0.142/4000	0.301/105200	0.250/87400
Welwitschia mirabilis	42^g	2/2	5981/958	0.063/2500	n.d.^h	0.007/3800	n.d.^h

Species	No. of chromosomes (2n)	No. of 18S/5S rDNA sites at metaphase^a	Estimated length of 35S/5S rDNA contigs (bp)	Estimated GP (%)/CN of 18S rDNA^b		Estimated GP (%)/CN of 5S rDNA^b
Species	No. of chromosomes (2n)	No. of 18S/5S rDNA sites at metaphase^a	Estimated length of 35S/5S rDNA contigs (bp)	Calculated from HTP^c	Slot-blot hybridization^d	Calculated from HTP^c	Slot-blot hybridization^d
Ephedra altissima	28^e	14–16	6766	0.058/6000	0.060/6200	0.010/15000	0.005/7700
Gnetum montanum	44^f	~6–8/>10	6527/627	0.132/3100	0.142/4000	0.301/105200	0.250/87400
Welwitschia mirabilis	42^g	2/2	5981/958	0.063/2500	n.d.^h	0.007/3800	n.d.^h

^aSite numbers are based on FISH (Fig. 5).

^bGP and CN, genome proportion and copy number of rDNA per 1C.

^cGP estimated by (the number of mapped reads) / (total number of reads analysed), CN was estimated by (GP×genome size) / (estimated rDNA sequence length) (Supplementary Data Table S1), the reference sequences were 120 bp of 5S and c.1800 bp of 18S rRNA genes from the assembled RE contigs.

^dGP and CN were estimated experimentally from slot-blot hybridization signals (Supplementary Data Fig. S10).

^eResende (1936) and this study.

^fWan et al. (2018) and this study.

^gFlorin (1932) and this study.

^hn.d. not determined.

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