Table 2. Comparison of the tuf barcode mean K2P intra- and inter-group divergences.

Phytoplasma group	Number of strains	K2P mean inter-group distance		K2P intra-group distance	Average inter−/intra-d ratio
		min	average
‘Ca. P. asteris’ 16SrI	16	0.129	0.322	0.024	13.418
‘Ca. P. aurantifolia’ 16SrII	10	0.128	0.380	0.049	7.753
‘Ca. P. pruni’ 16SrIII	11	0.272	0.315	0.028	11.247
Coconut lethal yellows 16SrIV	2	0.239	0.349	0.003	116.236
‘Ca. P. ulmi’ 16SrV-A	3	0.021	0.264	0	n/a
‘Ca. P. ziziphi’ 16SrV-B	1	0.061	0.265	n/c	n/c
‘Flavescence dorée’ 16SrV-C and -D	13	0.005	0.253	0.003	84.499
‘Ca. P.rubi’ 16SrV-E	1	0.005	0.253	n/c	n/c
‘Ca. P. trifolii’ 16SrVI	5	0.116	0.263	0.016	16.453
‘Ca. P. fraxini’ 16SrVII	4	0.116	0.256	0.020	12.821
‘Ca. P. phoenicium’ 16SrIX	2	0.257	0.332	0	n/a
‘Ca. P. mali’ 16SrX-A	3	0.049	0.295	0	n/a
‘Ca. P. prunorum’ 16SrX-B	2	0.050	0.301	0	n/a
‘Ca. P. pyri’ 16SrX-C	2	0.049	0.288	0	n/a
‘Ca. P. oryzae’ 16SrXI	3	0.285	0.352	0.131	2.687
Stolbur 16SrXII	10	0.134	0.313	0	n/a
‘Ca. P. australiense’ 16SrXII-B	1	0.129	0.332	n/c	n/c
‘Ca. P. brasiliense’ 16SrXV	1	0.128	0.364	n/c	n/c
‘Ca. P. rhamni’ 16SrXX	1	0.181	0.312	n/c	n/c

K2P genetic distances were calculated within (intra) and between (inter) phytoplasma groups. Minimum and average mean K2P inter-group divergences were calculated for all phytoplasma groups. Intra-group divergences could only be calculated for groups with more than one representative. K2P inter-group distance values greater than K2P intra-group distance values (or average inter−/intra-group divergence ratios >1) indicate that inter- and intra- group divergences do not overlap and suggest the presence of a barcoding gap. d, sequence divergence distance; n/a, not available; n/c, not calculated.