Virulence of Two Isolates of Meloidogyne enterolobii (Guava Root-Knot Nematode) from North Carolina on Cotton Lines Resistant to Southern Root-Knot Nematode (M. incognita ) and Reniform Nematode (Rotylenchulus reniformis ) Article Category: Research Paper Publié en ligne: 23 juin 2023 Pages: - Reçu: 26 août 2022 © 2023 Amanda G. Gaudin et al., published by Sciendo This work is licensed under the Creative Commons Attribution 4.0 International License.
Figure 1: Virulence of Meloidogyne enterolobii isolates 18-5126 and NC.1 on cotton germplasm lines resistant to M. incognita (RKN) (M240 RNR), resistant to RN (M713 Ren1), or resistant to both RKN and RN (M Rk-Rn-1) in comparison to a greenhouse-maintained RKN race 3 population. Also included were nematode-susceptible obsolete cultivars Deltapine61 (DPL61) and SureGrow747 (SG747). Eggs were used as inoculum and virulence was measured as (A) RF, (B) log10 eggs g−1 root, and (C) gall score index (1–10 scale). Tukey-Kramer multiple comparison was used to determine significant differences between means at α = 0.05 as denoted by different letters (n = 6). Figure 2: Virulence of Meloidogyne enterolobii isolates 18-5126 and NC.1 on cotton germplasm lines resistant to M. incognita (RKN) (M240 RNR), resistant to RN (M713 Ren1), or resistant to both RKN and RN (M Rk-Rn-1) using second-stage juveniles as inoculum. Also included were nematode-susceptible obsolete cultivars Deltapine61 (DPL61) and SureGrow747 (SG747). Virulence was measured as (A) RF ± SE, (B) log10 eggs g−1 root ± SE, and (C) gall score index ± SE (1–10 scale) of six replicates. Figure 3: Time-point dependent reproduction of the Meloidogyne enterolobii isolate NC.1 on cotton germplasm lines M240 RNR and MRk-Rn-1 in comparison to the susceptible cultivar SureGrow747 (SG747). Total eggs were extracted at 35-, 42-, 49-, and 56-days post inoculation (DPI). Isolate NC.1 reproduction is presented as (A) RF (total eggs extracted/initial inoculum) and (B) log10 eggs g−1 root. Significant differences between means at α = 0.05 noted by different letters (n = 6). Figure 4: Time-course of Meloidogyne enterolobii isolate NC.1 infection of SureGrow747 and MRk-Rn-1. Infected roots were collected at 4-, 8-, 12-, 16-, 20-, and 24-days after inoculation (DAI) and stained with acid fuchsin. Effect of Meloidogyne enterolobii infection on cotton growth under growth chamber conditions. Presented are mean ± SE after 6 weeks of growth under uninoculated (control) or inoculated conditions (n = 5).
Control
Inoculated
Stem Height (mm)
DPL61
124.1 ± 3.2
79.3 ± 3.7**
M240 RNR
147.8 ± 4.6
133.8 ± 22.8
SG747
143.5 ± 2.8
89.6 ± 2.1**
M713 Ren1
144.0 ± 17.0
131.0 ± 12.8
MRk-Rn-1
157.6 ± 10.5
111.6 ± 5.4**
Shoot Fresh Weight (g)
DPL61
2.49 ± 0.13
1.94 ± 0.23
M240 RNR
2.75 ± 0.23
2.01 ± 0.27
SG747
3.23 ± 0.45
1.48 ± 0.19**
M713 Ren1
2.58 ± 0.22
3.39 ± 0.42
MRk-Rn-1
2.99 ± 0.74
1.83 ± 0.11
Leaf Number
DPL61
3.7 ± 0.1
3.8 ± 0.4
M240 RNR
3.8 ± 0.1
3.5 ± 0.5
SG747
3.5 ± 0.2
2.4 ± 0.3**
M713 Ren1
3.9 ± 0.3
3.8 ± 0.3
MRk-Rn-1
4.1 ± 0.3
3.1 ± 0.2**
Stem Height/Node Number
DPL61
28.9 ± 0.5
21.1 ± 1.8**
M240 RNR
33.2 ± 1.9
33.2 ± 1.5
SG747
40.0 ± 2.3
26.5 ± 0.9**
M713 Ren1
31.7 ± 4.7
27.6 ± 2.2
MRk-Rn-1
40.5 ± 2.3
29.5 ± 1.1**