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Studies on biochemical variability for disease resistance in grape germplasm against powdery mildew (Uncinula Necator).

INTRODUCTION

Powdery mildew is one of the important disease caused by (Uncinula Necator) in grape (Vitis vinefera L.). Control of disease by fungicides particularly in fruit crops is difficult and hazardous for human health. Use of resistant Varieties is safe and eco-friendly. Hence biochemical characters were studied to find out which chemicals influence the disease resistance.

MATERIALS AND METHODS

Thirty eight grape genotypes (Cultivars/hybrids) available at Main orchard, Punjab Agricultural University (PAU), Ludhiana were used for the present study when the disease was in severe form and they were screened based on Percentage Disease Index (PDI) suggested by Varma et al., (1987) during September 1997. Out of thirty eight, 4 were found highly susceptible, 22 susceptible and 12 were resistant after screening in the field. Three varieties in each category of highly susceptible, susceptible and resistant were selected for biochemical analysis. RBD design was followed. Biochemical analysis was carried in both healthy and infected leaves of each category at IARI, New Delhi.

Varieties selected for biochemical analysis of leaves are,
a) Highly susceptible - 1.Perlette
 2. Anab-e-Shahi
 3. Gold

b) Susceptible - 1. New Perlette
 2. Centennial Seedless
 3. Bangui-Abyad

c) Resistant - 1. Red Globe
 2. St. George
 3. Ruby Seedless


Total phenols were estimated by method suggested by Swain & Hills, (1959) modified by Bhatia et al., (1972). Poly phenol oxidase and peroxidase enzymes were assayed by method suggested by Sadasivam and Manickam (1996).

RESULTS AND DISCUSSIONS

1. Total Phenols: More total phenols were observed (Table 1) in infected leaves over healthy leaves of same variety. It also shows resistant Varieties contain more total phenols than susceptible Varieties. St.George contains more total phenols (5.36 mg/g) over other varieties. Perlette which is highly susceptible variety contains lowest amount of total phenols (2.75 mg/g) over other varieties.

2. Poly phenol oxidase (PPO): It shows that, more activity of poly phenol oxidase enzyme (Table 1) was observed in infected leaves over healthy leaves of same variety. It also shows resistant Varieties contain more activity of poly phenol oxidase enzyme than susceptible Varieties. Ruby seedless contains more PPO (6.48 Units/g/mm) activity than other varieties. Gold which is highly susceptible Variety has less activity of PPO enzyme (4.85 Units/g/mm) over other varieties.

3. Peroxidase:--It shows that, more activity of peroxidase enzyme (Table 1) was observed in infected leaves over healthy leaves of same variety. It also shows resistant Varieties contain more activity of peroxidase enzyme than susceptible Varieties. St George shows more peroxidase enzyme (6.98 Units/g/mm) activity over other varieties. Perlette which is highly susceptible Variety has less activity of peroxidase enzyme (3.94 Units/g/mm) over other varieties.

Correlation Studies:--Total phenols are positively correlated with PPO (r=0.713) and peroxidase (r = 0.815) but negatively correlated (Table 2) with disease index (r = -0.840). PPO is positively correlated with peroxidase (r = 0.662) and negatively correlated with disease index (r = -0.724). The peroxidase is negatively correlated with disease index (r = -0.855).

In powdery mildew affected leaves total phenols and enzymes like PPO and peroxidase activity are more than the healthy leaves may be due to stress condition created by pathogen. The above observations are in accordance with the results obtained by Dhillon et al., (1992).

Total phenols and enzymes like PPO and peroxidase activity are more in resistant genotypes than susceptible genotypes. It shows that, the resistance against powdery mildew in grape genotypes due to higher total phenols and higher activity of oxidizing enzymes like PPO and peroxidase as these enzymes convert total phenols in to quinines which are toxic to the growth of powdery mildew fungus. The above observations are in accordance with the results obtained by Chander (1989) and Yurina et al., (1992).

CONCLUSIONS

Biochemical studies show that, resistance to the Powdery mildew pathogen in the grape genotypes might be due to higher levels of Total phenols, Polyphenol oxidase (PPO) and peroxidase.

ACKNOWLEDEMENTS

The author is grateful to Punjab Agricultural University (PAU), Ludhiana and IARI, New Delhi. for providing necessary facilities and guidance to complete this study.

REFERENCES

(1.) Bhatia, I.S. , Uppal, D.S. and Bajaj, K.L. 1972. Indian phyto pathol 25: 231-235.

(2.) Chander, M.S. 1989. Plant Disease Research, 4:1, 19-23: 12 ref

(3.) Dhillon, W.S. Bindra, A.S. and Kapoor, S.P. 1992. Plant Disease Research, 7: 248-250.

(4.) Sadasivam , S. and Manickam 1996. Biochemical method . 2nd ed., New Age International Publishers limited : 4835/24,

(5.) Swain, T. and Hills, W.E. 1959. J. Sci. Food Agric, 10: 63-68.

(6.) Varma, K.S., Cheema, S.S. and Bras, S.S. 1987. Punjab. Horti. J. 27 (1-2): 70-72.

(7.) Yurina, O.V. , Yurina, T.P. and Anikina, I. I. 1992. Sel' skokhazya- Isttvenna Ya Biologia. 1: 113-116.

K. Dhanumjaya Rao* and P.C. Jindal **

Dept. of Fruits and Horticulture Technology, Indian Agricultural Research Institute(IARI), New Delhi--110012, India

* Senior Scientist (Horti.),Farmers call centre, ANGRAU, Hyderabad(AP)E-mail :danu40138@yahoo.com,

** Senior Scientist (Horticulture) in Grapes, Dept. of Fruits and Horticultural Technology, IARI ,New Delhi
Table 1: Total phenols, Poly phenol oxidase and Peroxidase activity
in grape genotypes affected by powdery mildew.

 Total phenols Poly phenol oxidase
 (mg/g) (unit/min/g)

 Mean of Mean of Mean of Mean of
 diseased Healthy diseased Healthy
 leaves leaves leaves leaves

A) Highly susceptible

1. Perlette 2.75 2.69 4.89 2.29
2. Anab-e-Shahi 3.03 2.50 4.87 2.39
3. Gold 2.81 2.85 4.85 2.94
 Mean 2.86 2.68 4.87 2.54

B) Susceptible

1. New Perlette 3.80 3.07 5.32 2.81
2. Centennial 2.94 2.64 5.22 3.08
 Seedless
3. Banqui-Abyad 3.14 3.39 4.91 3.09
 Mean 3.29 3.03 5.15 2.99

C) Resistant

1. Red Globe 5.23 3.70 6.40 4.21
2. St. George 5.36 3.63 5.73 3.87
3. Ruby Seedless 4.84 3.74 6.48 4.88
 Mean 5.14 3.69 6.20 4.32
 Grand mean 3.76 3.11 5.37 3.33
 S.ED. 0.19748 0.13254 0.4027 0.42403
 CD at 5% 0.72333 0.4854 1.4750 1.55316

 Peroxidase
 (unit/min/g)

 Mean of Mean of
 diseased Healthy
 leaves leaves

A) Highly susceptible

1. Perlette 3.94 2.30
2. Anab-e-Shahi 4.14 2.48
3. Gold 3.96 3.05
 Mean 4.01 2.61

B) Susceptible

1. New Perlette 5.73 3.32
2. Centennial 4.35 3.28
 Seedless
3. Banqui-Abyad 5.83 3.27
 Mean 5.30 3.29

C) Resistant

1. Red Globe 5.86 3.68
2. St. George 6.98 4.97
3. Ruby Seedless 6.04 4.8
 Mean 6.29 4.48
 Grand mean 5.20 3.45
 S.ED. 0.284832 0.2037
 CD at 5% 1.0432 0.7463

* Significant at 5% level.

Table 2: Correlation studies between biochemical parameters and
disease index.

S. No. 1 2 3 4

1. Total phenols 1.000 0.713 0.815 -0.840
2. Poly phenol oxidase 1.000 0.662 -0.724
3. Peroxidase 1.000 -0.855
4. Percentage of Disease Index 1.000
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Author:Rao, K. Dhanumjaya; Jindal, P.C.
Publication:Bio Science Research Bulletin -Biological Sciences
Date:Jul 1, 2006
Words:1218
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