Cytokinin inhibits the growth of Leptosphaeria maculans and Alternaria brassicae

Figures & data

Fig. 1. Disease symptoms induced by L. maculans and A. brassicae isolates on detached leaves of Brassica plants. a, Effects of various concentrations of BAP treatments on the disease severity score (%) induced by L. maculans on B. napus or b, by A. brassicae isolate UAMH 7476, and c, Ontario on B. napus and B. carinata. Data were analyzed by ANOVA (P < 0.05) and different letters on the histogram (capital letters for ‘Westar’; lower case for ‘Carinata’ plants) indicate significant (P < 0.05) differences for each plant line under different concentrations of hormone treatments.

Fig. 2. Severity of disease symptoms induced by L. maculans and A. brassicae (Ontario isolate) on whole leaves of Brassica plants. Effects of various concentrations of BAP treatments on the disease severity score (%) induced by a, L. maculans on B. napus, and b, by A. brassicae on B. napus and B. carinata. Data were analyzed by ANOVA (P < 0.05) and different letters on the histogram (capital letters for ‘Westar’; lower case for ‘Carinata’ plants) indicate significant (P < 0.05) differences for each plant line under different concentrations of hormonal treatments.

Table 1.  Effect of cytokinins and other additives on colony growth of three phytopathogenic fungi

	Colony diameter (mm, average ± SE)
	L. maculans	*Significance	A. brassicae (UAMH 7476)	*Significance	A. brassicae (Ontario)	*Significance
No hormone	63.3 ± 1.30	B	62.0 ± 1.00	CD	41.0 ± 0.00	A
BAP (0.2 mM)	57.7 ± 0.88	C	27.0 ± 1.00	G	19.3 ± 1.67	D
BAP (0.5 mM)	53.7 ± 0.33	D	1.00 ± 0.00	I	1.00 ± 0.00	F
BAP (1. 0 mM)	51.3 ± 0.33	E	No growth	I	No growth	F
Kinetin (0.2 mM)	63.3 ± 0.67	B	49.3 ± 0.88	E	32.7 ± 3.33	B
Kinetin (0.5 mM)	64.0 ± 1.15	B	33.3 ± 1.45	F	24.3 ± 3.33	C
Kinetin (1.0 mM)	62.7 ± 0.67	B	21.0 ± 0.00	H	12.7 ± 1.67	E
No chemicals	71.0 ± 0.0.0	A	60.0 ± 1.50	D	35.0 ± 0.60	B
Adenine (0.2 mM)	71.0 ± 0.00	A	65.3 ± 0.67	AB	37.0 ± 2.08	AB
Adenine (0.5 mM)	71.0 ± 0.00	A	63.0 ± 1.00	ABC	35.0 ± 1.00	B
Adenine (1.0 mM)	70.7 ± 0.33	A	65.7 ± 0.67	A	35.7 ± 0.33	B
AHS (0.2 mM)	71.0 ± 0.00	A	63.7 ± 0.33	ABC	34.7 ± 1.33	B
AHS (0.5 mM)	70.3 ± 0.67	A	62.7 ± 1.20	BCD	35.0 ± 1.00	B
AHS (1.0 mM)	70.3 ± 0.67	A	64.0 ± 1.00	ABC	34.7 ± 1.33	B
Notes: *Different letters in the Significance column indicate a statistical significance for each pathogen under different treatments. Data for each pathogen were analyzed with the generalized linear model procedure for ANOVA followed by Duncan's multiple range test (P < 0.05) using SAS software version 9.1.

Fig. 3. Histological studies of responses of hormone-treated and untreated leaves of whole plants. Panels in (a) illustrate the effects of various concentrations of BAP on the interaction of B. napus (‘Westar’) leaves with L. maculans; with A. brassicae (Ontario isolate), (b); and B. carinata with A. brassicae (Ontario isolate), (c). The arrows with M indicate fungal mycelia, and P indicate pycnidia.