A qRT-PCR method to evaluate viability of potato cyst nematode (Globodera spp.)

Figures & data

Fig. 1 Standard curves for the amplification of the gpd1 gene on synthetic complementary DNA (squares) or on RNA extracted from viable eggs of Globodera rostochiensis (circles). Three independent replicates were carried out for each concentration.

Table 1. Effect of different treatments and different numbers of eggs of three Globodera species on the quantification cycle (Cq) of gpd1 messenger RNA by qRT-PCR.

Species	Treatment	No. of eggs	Cq (Mean ± SD)
G. rostochiensis	Untreated	1	36.77 ± 0.30
G. rostochiensis	Untreated	5	34.22 ± 0.38
G. rostochiensis	Untreated	10	33.65 ± 0.42
G. rostochiensis	Untreated	25	32.83 ± 0.38
G. rostochiensis	Untreated	50	30.70 ± 0.37
G. rostochiensis	Untreated	100	29.70 ± 0.38
G. rostochiensis	Untreated	500	27.69 ± 0.26
G. rostochiensis	Heat at 65°C	10	No Cq
G. rostochiensis	Autoclave	10	No Cq
G. rostochiensis	Methyl bromide	10	No Cq
G. rostochiensis	Untreated	25	32.83 ± 0.38
G. rostochiensis	Cyst shells	25	32.93 ± 0.57
G. pallida	Untreated	25	32.24 ± 0.76
G. pallida	Untreated	100	29.93 ± 0.22
G. ellingtonae	Untreated	25	31.63 ± 0.78
G. ellingtonae	Untreated	100	29.37 ± 0.43

Table 2. Estimation, by visual evaluation and qRT-PCR, of Globodera rostochiensis egg viability from 50 cysts that developed on the susceptible potato cultivar ‘Snowden’ in microplots.

	No. of viable eggs
Microplot	Visual	qRT-PCR
1	2375	3639.0
2	319	1324.2
3	895	740.4
4	1319	2547.0
5	342	1593.3

Fig. 2 Evaluation of Globodera rostochiensis population density (cysts and viable eggs) after five continuous years of cropping with resistant potatoes (cv. Andover) in microplots located in Saint-Amable, Quebec, Canada.

Table 3. Evaluation of Globodera rostochiensis population densities (cysts and viable eggs) 10 years after the establishment of quarantine procedures (including two crops of resistant potatoes) in 24 fields located in Saint-Amable, Quebec, Canada.

Field	Cyst density (cysts kg^−1 soil ± SD)	Viability (Cq ± SD)	Viability (viable eggs kg^−1)	EIPC^1 (Cq ± SD)
2015–1	723.5 ± 60.2	No Cq	0	28.80 ± 0.29
2015–2	530.7 ± 59.6	No Cq	0	28.67 ± 0.16
2015–3	408.2 ± 146.1	No Cq	0	28.68 ± 0.53
2015–4	417.9 ± 23.2	No Cq	0	28.90 ± 0.78
2015–5	730.4 ± 41.2	No Cq	0	28.90 ± 0.46
2015–6	3.6 ± 2.7	No Cq	0	29.41 ± 0.15
2015–7	2.7 ± 1.2	No Cq	0	29.08 ± 0.34
2015–8	133.6 ± 15.7	No Cq	0	28.75 ± 0.65
2015–9	3.9 ± 1.8	No Cq	0	28.85 ± 0.49
2015–10	7.3 ± 5.3	No Cq	0	29.12 ± 0.40
2015–11	5.1 ± 3.5	No Cq	0	29.78 ± 0.41
2015–12	1.4 ± 0.6	No Cq	0	29.00 ± 0.43
2015–13	1.4 ± 1.0	No Cq	0	28.91 ± 1.03
2016–1	1.3 ± 0.5	No Cq	0	29.21 ± 0.61
2016–2	1.9 ± 1.3	No Cq	0	29.55 ± 0.25
2016–3	145.4 ± 35.5	35.59 ± 1.81	11.8 ± 13.2	28.99 ± 0.18
2016–4	267.2 ± 7.4	37.22 ± 1.06	2.8 ± 1.9	29.07 ± 0.35
2016–5	1.5 ± 0.1	No Cq	0	29.23 ± 0.31
2016–6	1.9 ± 0.7	No Cq	0	28.91 ± 0.25
2016–7	6.3 ± 5.7	No Cq	0	29.06 ± 0.21
2016–8	10.1 ± 4.6	No Cq	0	29.55 ± 0.65
2016–9	24.3 ± 12.1	No Cq	0	28.82 ± 0.07
2016–10	19.3 ± 3.4	No Cq	0	29.32 ± 0.88
2016–11	16.3 ± 4.0	No Cq	0	29.41 ± 0.64
Control	5.0 ± 0.0	25.19 ± 0.34	3403.5 ± 696.5	29.02 ± 0.83

¹EIPC: Exogenous internal positive control.