Table 1.
Characterization of two isolates of Fusarium oxysporum f. sp. ciceris (races 0 and 5) transformed with the ZsGreen fluorescent protein.
Figure 1.
Early stages of chickpea root infection by Fusarium oxysporum f. sp. ciceris races 0 and 5 in compatible and compatible interactions.
(a, b) germinated conidia on the root apex with primary mycelia at 1 dai; (c–d) primary mycelia and initial hyphal colonization on lower root zone at 2 dai; (e) intermediate root zone showing hyphal colonization with mycelium extending from the epidermis into cortical tissues at 6 dai; (f) conidia on the root surface with germ tube(s) at 1 dai; (g) germinated conidia on the root surface with primary mycelia at 1 dai. The Fusarium oxysporum f. sp. ciceris isolates were transformed with the ZsGreen fluorescent protein and imaged using confocal laser scanning microscopy. dai: number of days after inoculation.
Figure 2.
Temporal and spatial patterns of chickpea infection by Fusarium oxysporum f. sp. ciceris race 0.
Colonization of three cultivars, including P-2245 (susceptible, S), JG-62 (resistant, R), and WR-315 (R) was imaged using confocal laser scanning microscopy. ep: epidermis, c: cortex, x: xylem, dai: number of days after inoculation. (a–c): root apex; (d–i): lower root zone; (j): upper root zone; (k): intermediate root zone; (l): lower root zone; (m): stem fifth internode; (n): stem fourth internode; (o): half root zone. The Fusarium oxysporum f. sp. ciceris isolate was transformed with the ZsGreen fluorescent protein.
Figure 3.
Advanced stages of chickpea infection by Fusarium oxysporum f. sp. ciceris races 0 and 5 in compatible and compatible interactions.
Left panels: cross sections; Right panels: longitudinal sections. (a,b) intercellular colonization of cortical root tissue occurring in all compatible and incompatible interactions; (c–d) intercellular colonization of cortical root tissue and fungal mycelia through root xylem vessels occurring in all compatible interactions and in the incompatible interactions of cv. JG-62/race 0 and cv. WR-315/race 5; (e–f) heavy colonization of xylem stem vessels occurring in all compatible interactions and in the incompatible interaction of cv. JG-62/race 0. The Fusarium oxysporum f. sp. ciceris isolates were transformed with the ZsGreen fluorescent protein and imaged using confocal laser scanning microscopy. c: cortex, x: xylem.
Figure 4.
Temporal and spatial patterns of chickpea infection by Fusarium oxysporum f. sp. ciceris race 5.
Colonization of three cultivars, including P-2245 (susceptible, S), JG-62 (S), and WR-315 (resistant, R) was imaged using confocal laser scanning microscopy. ep: epidermis, c: cortex, x: xylem, dai: number of days after inoculation. (a–c): root apex; (d–i): lower root zone; (j): stem second internode; (k): epicotyl; (l): lower root zone; (m): stem fourth internode; (n): stem third internode; (o): lower root zone. The Fusarium oxysporum f. sp. ciceris isolate was transformed with the ZsGreen fluorescent protein.
Table 2.
Colonization process of different parts of three chickpea cultivars showing differential resistance by Fusarium oxysporum f. sp. ciceris races 0 and 5a.
Figure 5.
Intensity of vascular colonization (ItCV) by races 0 and 5 of Fusarium oxysporum f. sp. ciceris.
The Fusarium oxysporum f. sp. ciceris (Foc) isolates were transformed with the ZsGreen fluorescent protein. Plants were sampled daily from 1 to 4 days after inoculation (dai), and at 2 days intervals from 6 to 18 (dai). Tissues sampled included: Root: lower and intermediate zone of the tap root (a, e); Hypocotyl (b, f) and epicotyl (c, g): zones immediately before and after the insertion of cotyledons, respectively; Stem (d, h): internodes one to fifth of the main stem. Severity (S) indicate the disease severity (DS) level of foliar symptoms assessed at each sampling time using a 0 to 4 scale based on the percentage of affected foliar tissue (0 = 0%, 1 = 1 to 33%, 2 = 24 to 66%, 3 = 67 to 100%, and 4 = dead plant). S = 0: no symptoms; S = L: initial symptoms (0<DS<2); S = M: moderate symptoms (2<DS≥3); and S = S: severe symptoms (DS≥3), for Foc-0 (first character) and Foc-5 (second character). There were four plants (two plastic pots) per F. oxysporum f. sp. ciceris race/chickpea cultivar combination analysed for each sampling time. The experiments were arranged in a randomized complete blocks design, and were repeated twice. For each sampled tissue, vascular colonization was assessed on four blocks with 20 cells (xylem vessels) per block, covering the entire vascular cylinder. Error bars indicate the standard error of the mean. Significant differences (P<0.05) between ItCV level reached on races 0 and 5 for each chickpea cultivar/tissue combination at each sampling date are indicated by an asterisk.
Figure 6.
Intensity of vascular colonization (ItCV) by races 0 and 5 of Fusarium oxysporum f. sp. ciceris at early and advanced stages of plant colonization.
(a) ItCV mean values at early stages of plant colonization, i.e., sampling times in which no disease symptoms develop in the compatible interactions. (b) ItCV mean values at advanced stages of plant colonization, i.e., at sampling times in which symptoms develop in compatible interactions. The Fusarium oxysporum f. sp. ciceris (Foc) isolates were transformed with the ZsGreen fluorescent protein. I: incompatible interaction; C: compatible interaction. Plants were sampled daily from 1 to 4 days after inoculation (dai), and at 2 days intervals from 6 to 18 (dai). Tissues sampled included: Root: lower and intermediate zone of the tap root; Hypocotyl and epicotyl: zones immediately before and after the insertion of cotyledons, respectively; Stem: internodes one to fifth of the main stem. There were four plants (two plants per pot) per F. oxysporum f. sp. ciceris race/chickpea cultivar combination analysed for each sampling time. The experiments were arranged in a randomized complete blocks design, and were repeated twice. For each sampled tissue, vascular colonization was assessed on four blocks with 20 cells (xylem vessels) per block, covering the entire vascular cylinder. Error bars indicate the standard error of the mean. Significant differences (P<0.05) between ItCV level reached at races 0 and 5 for each chickpea cultivar are indicated by an asterisk.
Table 3.
Effects of sampling time and plant tissue on vascular colonization intensity by Fusarium oxysporum f. sp. ciceris (Foc) races 0 and 5 in chickpea cultivars showing differential resistance.