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Molecular Microbiology Research (Online) 2013, Vol.3 No.3 20-29
ISSN 1927-5595
http://mmr.sophiapublisher.com
21
Table 1 Efficacy of plant oil, bio control agents, micronutrient and fungicides against leaf blight disease under glasshouse conditions
S. No
Treatments
*Per cent disease index
Plant height (cm)
1
Mancozeb (0.2%)
18.44
a
(25.42)
148.25
a
2
Pseudomonas fluorescens
(0.2%)
26.81
d
(31.17)
130.20
e
3
Bacillus
sp EPCO16 (0.2%)
30.32
e
(33.40)
127.40
f
4
Lemon grass oil (0.1%)
34.24
f
(35.80)
120.20
g
5
Copper sulphate (0.1%)
36.00
i
(36.86)
99.80
j
6
Control
56.73
j
(48.87)
87.50
k
Note: *Values are the mean of four replications; Values in parentheses are arcsine transformed. Means followed by a same letter are
not significantly different at the 5 % level by DMRT
1.2 Induction of defense mechanism in plants
1.2.1 Changes in the phenylalanine ammonia lyase
(PAL) activity in physic nut plants treated with
plant oil, bio control agents and micronutrient
The phenylalanine ammonia lyase (PAL) activity
gradually increased in physic nut leaves following
treatments with
P. fluorescens
,
Bacillus
EPCO16,
Copper sulphate and Lemon grass oil which reached
maximum level at 5
th
day after treatment when
compared to control. However the enzyme activity
declined subsequently. Among them, Pf1 recorded
maximum PAL activity (22.303 n mol of transcinnamic
acid min
-1
g
-1
of fresh tissue) followed by
Bacillus
EPCO16 (21.030 n mol of transcinnamic acid min
-1
g
-1
of fresh tissue), Copper sulphate (19.160 n mol of
transcinnamic acid min
-1
g
-1
of fresh tissue) and Lemon
grass oil (17.710 n mol of transcinnamic acid min
-1
g
-1
of fresh tissue) on 5
th
day and thereafter declined. The
plants treated with pathogen alone recorded (11.210 n
mol of transcinnamic acid min
-1
g
-1
of fresh tissue)
only slight increase in PAL activity, while the healthy
plant recorded lesser PAL activity (8.230 n mol of
transcinnamic acid min
-1
g
-1
of fresh tissue) (Figure 1A).
1.2.2. Changes in the peroxidase (PO) activity in
physic nut plants treated with plant oil, bio control
agents and micronutrient
The activity of peroxidase gradually increased in
physic nut leaves following treatments with
P.
fluorescens
,
Bacillus
EPCO16, Copper sulphate,
Lemon grass oil reached maximum level at 5
th
day
after treatment when compared to control. The
enzyme activity subsequently declined. Among them,
Pf1 recorded maximum PO activity (3.790 changes in
A
420
min
-1
g
-1
of fresh tissue) followed by
Bacillus
EPCO16 (3.240 changes in A
420
min
-1
g
-1
of fresh
tissue), Copper sulphate (2.660 changes in A
420
min
-1
g
-1
of fresh tissue) and Lemon grass oil (2.590
changes in A
420
min
-1
g
-1
of fresh tissue) on 5
th
day and
thereafter declined. The plants treated with pathogen
alone recorded (2.260 changes in A
420
min
-1
g
-1
of fresh
tissue) only slight increase in PO activity. The healthy
plant recorded lesser PO activity (2.080 changes in
A
420
min
-1
g
-1
of fresh tissue) (Figure 1B).
1.2.3. Changes in the polyphenol oxidase (PPO)
activity in physic nut plants treated with plant oil,
bio control agents and micronutrient
The polyphenol oxidase (PPO) activity gradually
increased in physic nut leaves following treatments
with
P. fluorescens
,
Bacillus
EPCO16, Copper
sulphate and Lemon grass oil reached maximum level
at 5
th
day after treatment when compared to control.
The enzyme activity subsequently declined. Among
them, Pf1 recorded maximum PPO activity (2.820
changes in A
490
min
-1
g
-1
of fresh tissue) followed by
Bacillus
EPCO16 (2.570 changes in A
490
min
-1
g
-1
of
fresh tissue), Copper sulphate (2.210 changes in A
490
min
-1
g
-1
of fresh tissue) and Lemon grass oil (1.970
changes in A
490
min
-1
g
-1
of fresh tissue) on 5
th
day and
thereafter declined. The plants treated with pathogen
alone recorded (1.850 changes in A
490
min
-1
g
-1
of fresh
tissue) only slight increase in PPO activity. The
healthy plant recorded lesser PPO activity (1.570
changes in A
490
min
-1
g
-1
of fresh tissue) (Figure 1C).
1.2.4. Changes in the β-1, 3 glucanase activity in
physic plants treated with plant oil, bio control
agents and micronutrient
The β-1, 3 glucanase activity gradually increased in
physic nut leaves following treatments with
P.
fluorescens
,
Bacillus
EPCO16, Copper sulphate and