The effect of methyl salicylate on the induction of direct and indirect plant defense mechanisms in poplar (Populus × euramericana ‘Nanlin 895’)

Figures & data

Figure 1. The activity change in SOD (A), POD (B), CAT (C), and PPO (D) in poplar leaves after treatment with MeSA for different lengths of time.

Note: All values are mean ± standard deviation of the mean (SD). Different letters indicate significant differences between the treatment and the control (P < 0.05; t test).

Figure 2. Volatile compound content changes in poplar treated by MeSA. Typical gas chromatograms (on a DB-WAX column) of volatile compounds emitted from control (non-MeSA treated plants) (A) and MeSA treated plants (B) after 24 h and the content changes of 19 low-quantity volatile compounds in poplar treated for 24 h (C), 48 h (D), and 72 h (E).

Notes: The bars represent hexyl formate (1), (Z)-butanoic acid-3-hexenyl ester (2), cis-3-hexenyl-2-methylbutyrate (3), 2-ethyl-1-hexanol (4), unknown (5), 2-hydroxy-benzaldehyde (6), 2,6-dimethyl-5-heptenal (7), methylsalicylate (8), methoxy-phenyl-oxime- (9), geraniol (10), phenol (11), eugenol (12), dibutylphthalate (13), (Z)-3-nonen-1-ol (14), (E)-2-hexen-1-ol (15), 1-octanol (16), (E,Z)-3,6-nonadien-1-ol (17), β-ionone (18), and hexadecanamide (19). Each compound was more than 80% matched. For each number, different small letters indicate statistically significant differences in volatile release concentrations between the treated and the control plants (GraphPad InStat version 3.00; N = 3; P < 0.05).

Table 1. The content changes of six volatile compounds only produced in the treated leaves (among 19 low-quantity volatile compounds) at the different time periods.

	Concentration (µg g^−1) ± SD
Compound	24 h	48 h	72 h
(Z)-3-Nonen-1-ol	7.91 ± 0.56a	6.83 ± 0.25b	NDc
(E)-2-Hexen-1-ol	15.19 ± 0.85a	6.84 ± 0.58b	3.73 ± 0.07c
1-Octanol	4.15 ± 0.02b	4.85 ± 0.52b	8.52 ± 0.44a
(E,Z)-3,6-Nonadien-1-ol	4.56 ± 0.18c	13.37 ± 0.32a	6.66 ± 0.25b
β-Ionone	4.07 ± 0.03a	4.14 ± 0.25a	3.63 ± 0.13b
Hexadecanamide	9.16 ± 0.64a	3.97 ± 0.13b	3.50 ± 0.03b

Notes: ND means that the compound was not detected. The same compounds at the various time periods with different small letters have significantly different volatile release concentrations (GraphPad InStat version 3.00; N = 3; P < 0.05).

Figure 3. Concentrations of high-volume volatile compounds: cis-3-hexenyl acetate (20) and (Z)-3-hexen-1-ol (21), in poplar leaves at the 24, 48, and 72 h time periods.

Note: Columns with an asterisk or with different small letters have significantly different volatile release concentrations between the treated and control leaves (GraphPad InStat version 3.00; N = 3; P < 0.05).