Phenolic acid content in potato peel determines natural ... - Springer Link

World J Microbiol Biotechnol (2011) 27:1559–1567 DOI 10.1007/s11274-010-0608-z

ORIGINAL PAPER

Phenolic acid content in potato peel determines natural infection of common scab caused by Streptomyces spp. Prince K. Singhai • Birinchi K. Sarma Jai S. Srivastava

•

Received: 1 July 2010 / Accepted: 2 November 2010 / Published online: 17 November 2010 Ó Springer Science+Business Media B.V. 2010

Abstract Common scab of potato caused by the actinomycete Streptomyces scabies is a common pathogen in almost all the potato growing areas of the world. Twenty cultivars of potato were screened in naturally scab infested farmers fields at two locations Tikari and Bachhawan, Varanasi, in two successive crop seasons (2006–2007 and 2007–2008). Among the cultivars, five cultivars were recorded to be least susceptible and the others ranged from medium susceptible to very highly susceptible. Most of the cultivars showed a stable resistance reaction in both the years. Qualitative as well as quantitative estimation of phenolic acids present in peels of the potato cultivars showed their possible role in protection of the potato cultivars against common scab. All the red skinned potato cultivars that were least susceptible to common scab infection were usually found to be rich in phenolic acid contents in their peels. This showed a positive correlation between cultivar resistance to common scab and phenolic acid content in the peel. Keywords Resistance Potato cultivars Actinomycete Phenolic acids

P. K. Singhai Mycology and Plant Pathology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221 005, India e-mail: [email protected] B. K. Sarma (&) J. S. Srivastava (&) Mycology and Plant Pathology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221 005, India e-mail: [email protected] J. S. Srivastava e-mail: [email protected]

Introduction Common scab of potato is caused by the actinomycete Streptomyces scabies (Thaxter) Waskman and Henrici, and it occurs in almost all the potato growing areas of the world (Marais and Vorster 1988; Keinath and Loria 1989). It is primarily soil-borne but can also be seed transmitted (Lehtonen et al. 2004). Other than S. scabies, species like S. griseus, S. aureofaciens and S. flaveolus, also cause scab diseases of economically important root and tuber crops. In 1989, a new group of phytotoxin associated with plant pathogenic Streptomyces was discovered and named Thaxtomin (King et al. 1989). Thaxtomin A was first isolated from scabby tubers of potato and is considered as one of the major phytotoxins produced by S. scabies. A large number of evidences exist that show a major role of thaxtomin A in pathogenicity of S. scabies (Healy et al. 2002; King et al. 1991; Loria et al. 2008). According to Lawrence et al. (1990), application of purified thaxtomin A on potato mini-tubers caused necrosis on treated tissues. It also inhibits growth of various crops namely radish (Raphanus sativus L.), alfalfa (Medicago sativa L.), cauliflower (Brassica oleracea L.), colza (Brassica napus L.) and turnip (Brassica rapa L.). King et al. (1991) also reported a positive correlation between thaxtomin-A production and pathogenicity of S. scabies. In India, S. scabies was first reported by Mc Rae in 1929 from the Khasi Hills of Meghalaya. It had detrimental effect on tuber appearance, grade, marketable yield and prices. King et al. (1992) considered common scab as a disease of major economic importance. It is now becoming a major problem in almost all agro climatic zones of India (Nagaich 1983). It is moderately prevalent in the hilly areas of Uttar Pradesh, Meghalaya and West Bengal and was known to occur in Lahaul Valley (Himanchal Pradesh) in severe form

123

1560

since 1969. Although it has occurred in the plains since 1960 (Paharia and Pushkarnath 1963), it is frequently reported to occur in plains since 1979–1980 (Sharma 1984). Now the disease has covered almost all the potato growing areas of the country and is now posing a serious threat to successful potato cultivation. In Eastern Uttar Pradesh, the disease has been reported to occur every year either in moderate or severe form (Mishra and Srivastava 1999; Mishra and Srivastava 2001; Mishra and Srivastava 2005). Various control measures, viz., application of chemicals like Terrachlor and Terrachlor-X, acidification by sulphur (Davis et al. 1974), soil amendments (Mishra and Srivastava 2005), organic amendments (Lazarovits et al. 2001), soil fumigation, green manuring (Mishra and Srivastava 2005), crop rotation, soil pH regulation (Waterer 2002), excess irrigation during tuber formation (Loria et al. 1997), potato seed bacterization and use of agrochemicals (Neeno-Eckwall et al. 2001) have been suggested but so far no full proof management practices for common scab of potato is available. It is now widely accepted that satisfactory and ecofriendly management of common scab cannot be accomplished without genetic resistance, which is most ecofriendly and stable method to manage any disease. Management of diseases through varietal resistance is a cheap and long lasting practice and is widely popular among the farmers. However, to select the best cultivar, it is necessary to screen the available potato cultivars against the common scab pathogen. Although the environment is full of phytopathogenic and saprophytic microorganisms, plants survive successfully in majority of these conditions. This can be explained well that the protective phenomenon of plants is governed by their pre-existing defense mechanism(s), which is composed of physical and chemical structures functioning as defense barriers against the invading microorganisms (Collinge et al. 1997). Preformed chemical barriers have wide chemical spectrum (Dennis et al. 1997) and composed of several compounds such as terpenoids, glycosides, chalchones, phenolics and peptides. Flavonoids act as antimicrobial agents in protecting the plants (Hahlbrock and Scheel 1989) whereas antimicrobial phenols have been known to occur in many plants. Some of them occur constitutively while others are formed in response to pathogen ingress and associated as part of an active defense response in the host (Kuc 1995). The constitutive phenolics are known to confer resistance either directly (De Vecchi and Matta 1989) or indirectly through activation of post infection responses in the hosts (Harborne 1988; Sarma et al. 2002; Singh et al. 2002a). The high amount of secondary metabolites in the host usually correlated with inhibition of growth and development of the invading pathogens (Madamanchi and Kuc 1991; Singh et al. 2003). Among the secondary metabolites phenolic acids play a

123

World J Microbiol Biotechnol (2011) 27:1559–1567

significant role in restricting the pathogen invasion (Nicholson and Hammerschmidt 1992). Therefore, different potato cultivars having diverse genetic background were screened in naturally scab infested farmers’ fields to identify the level of resistance under normal growing conditions. A repeated experiment was conducted to determine the consistency of the cultivars’ resistance behaviour against common scab over successive years. To determine the involvement of secondary metabolites as possible contributory factors to resistance against S. scabies in the potato cultivars other than their genetic makeup, presence of phenolic acids in the peels of the potato cultivars was evaluated and the results are presented here.

Materials and methods Twenty potato cultivars were obtained from Central Potato Research Institute, Patna and planted in naturally scab infested farmers’ fields at two locations Tikari and Bachhawan, Varanasi, in two successive crop seasons (2006–2007 and 2007–2008). The cultivars were interspersed with check, cv. Kufri Chandramukhi. The fields selected for the experiment had been under potato cultivation for the past 10 years and common scab was found to occur regularly, as evident from the survey reports of Mishra and Srivastava (1999); Mishra and Srivastava (2001). The soil was sandy loam, pH 7.1 with nitrogen, phosphorous and potash quantities of 320, 20 and 200 kg/ ha, respectively. The experiment was conducted in a randomized block design with plots of 1.5 9 1 m in three replicates, as described by Bjor and Roer (1980). Soil was fertilized with 70 kg N, 80 kg P and 70 kg K, before planting and 50 kg N as a top dressing. Plants were grown until the foliage died. Three sprayings of 0.25% Dithane M-45 were made at 15 days intervals to control foliar diseases. Tubers harvested from each plot were graded before scoring. Tubers more than 2.5 cm in diameter were scored individually for scab occurrence according to the scale of Bjor and Roer (1980) with some modifications as followsScale A—percentage of tuber area covered: 1. 0–10%; 2. 10–25%; 3. 25–50%; 4. 50–75%; 5. 75–100%. Scale B—lesion type: 1. Superficial scab; 2. Medium deep or raised scab; 3. Deep scab. Scab index (SI) was calculated for each tuber as: SI ¼

Percentage surface area covered Lesion type 100 15

and averaged over all tubers of each cultivar.


Scab incidence (SIc) was calculated as: SIc ¼

Number of infected tubers 100 Total number of tubers

Potato cultivars were grouped as least susceptible, medium susceptible, highly susceptible and very highly susceptible as suggested by Marais and Vorster (1988) with slight modification in the terms used for grouping.

Scab index

Class

8–15

Least susceptible

15–20

Medium susceptible

20–24

Highly susceptible

[24

Very highly susceptible

Statistical analysis All the data were analyzed statistically with computer software SPSS and subjected to least significant differences (LSD) multiple mean comparison test (Steel and Torrie 1980).

Extraction of phenolic compounds Peels of 20 Indian potato cultivars were taken for analyses of phenolic compounds. Ten randomly selected tubers of each cultivar were taken and the peel off served as one sample. One gm of tuber peel from each cultivar was macerated using a pestle and mortar followed by suspension of finely crushed samples in 5 ml of 80% ethanol. Further extraction of phenolic acids was done according to Singh et al. (2002b). Samples were collected separately in screw capped tubes and the suspension was subjected to ultrasonication (Branson sonifier, Branson Ultrosonics Corp., Danburry, USA) at 60% duty cycles for 15 min at 4°C followed by centrifugation at 7,500 rpm for 15 min. The clear yellowish supernatant was subjected to charcoal treatment to remove pigments in each sample and transferred to glass tubes after filtering through whatman filter paper no 1. The residue was re-extracted twice with 80% ethanol and the supernatant was pooled prior to evaporation under vacuum (Buchi Rotavapor Re Type, Macro Scientific Works, Delhi, India). Dried samples were re-suspended in 1 ml of HPLC grade methanol by vortexing and stored at 4°C for further analyses. High performance liquid chromatography (HPLC) analysis Samples prepared for phenolic acid estimation were analyzed through HPLC according to the method described by

1561

Sarma et al. (2002). The HPLC system (Shimadzu Corporation, Kyoto, Japan) was equipped with two Shimadzu LC—10 AT VP reciprocating pumps, a variable UV-VIS detector (Shimadzu SPD—10 A VP) and a Class VP integrator (Shimadzu Corporation, Kyoto, Japan). Reverse phase chromatographic analysis was carried out using a C—18 reverse phase HPLC column (250 9 4.6 mm inner diameter, particle size 5 lm Luna 5 lc—18, Phenomenex, Torrance, USA) at 25°C under isocratic conditions where the concentration of mobile phase was constant throughout the run. Running conditions included an injection volume of 5 ll. Mobile phase methanol-0.4% acetic acid (80:20 v/ v), flow rate 1 ml min-1, attenuation 0.03 and detection at 290 nm. Samples were filtered through membrane filters (pore size 0.45 lm, Merck (India) Ltd., Mumbai, India) prior to injection in the sample loop. Gallic, hydroxy cinnamic, ferulic, chlorogenic, O-coumaric and cinnamic acids were used as internal and external standards. Phenolic acids present in the samples were identified by comparing the retention time (Rt.) of standards and by co-injection. Concentration was calculated by comparing peak areas of reference compounds with those in the samples run under the same elution conditions. All the samples were run for three times. The data were subjected to ANOVA and means were compared with the Least Significant Difference (LSD) test for statistical significance.

Results Scab index and incidence in field trials Mean scab incidence and scab index of the twenty potato cultivars in two locations (Tikari and Bachhawan), in the year 2006–2007 and 2007–2008 are given in Tables 1, 2, 3, 4. The results of the field experiments clearly revealed that all the twenty cultivars were different in their responses to scab incidence and scab index. Although none of the cultivars were completely resistant to the scab pathogen, five cultivars i.e. Kufri Sinduri, Kufri Lalima, Kufri Deva, Kufri Arun and Kufri Kanchan were observed as least susceptible. Kufri Sinduri was found to be the least susceptible cultivar with the per cent scab index i.e. 9.10 and 10.18 and scab incidence 15.75 and 18.94 in two consecutive years 2006–2007 and 2007–2008 in Tikari (Tables 1, 2). The same cultivar also showed least scab index (9.96, 10.68) and scab incidence (13.40, 19.01) in the years 2006–2007 and 2007–2008 in Bachhawan. Another cultivar Kufri Lalima was also grouped as least susceptible cultivar with per cent scab index (10.55, 10.92) and incidence (15.46, 24.13) in 2 years 2006–2007 and 2007–2008 at the experimental field in Tikari. The same cultivar was screened with other test cultivars of potato, at the experimental field in Bachhawan

123

1562 Table 1 Scab index and scab incidence of potato cultivars screened in Tikari in 2006–2007


S. No.

Varieties

1

Kufri Sinduri

2

Kufri Lalima

3

Kufri Deva

4

18.65c ± 4.26

10.88abc ± 2.14

cd

± 2.25

11.54bcd ± 2.04

cde

20.91

6

Kufri Lavker

22.35cdef ± 1.95

15.12ef ± 1.68

7

Kufri Badsah

8

Kufri Bahar Kufri Chipsona-1

10

Kufri Muthu

11

Kufri Chipsona-2 Kufri Ashoka Kufri Surya Kufri Satlaz

defg

± 0.60

15.32fg ± 1.21

27.78gh ± 3.44

15.99fgh ± 3.52

24.41

ghi

± 5.48

16.10fghi ± 1.05

ghij

± 1.53

16.20fghij ± 1.32

26.60fghijk ± 2.52

16.54fghijk ± 1.96

27.91 28.63

efghijkl

± 1.91

16.95fghijkl ± 1.42

fghijklm

± 3.66

18.88hijklm ± 1.92

ghijklmn

± 2.95

19.18jklmn ± 1.72

26.02 26.87 28.82

15 16

Kufri Puskar Kufri Pukhraj

31.73 ± 3.86 32.70jnop ± 3.58

20.07mno ± 1.23 20.81mnop ± 0.72

17

Kufri Anand

34.10opq ± 2.01

21.01mnopq ± 0.55

18 19

Kufri Megha

hijno

Kufri Chandramukhi

S.No.

Varieties

1

Kufri Sinduri

2

Kufri Lalima

3

Kufri Deva Kufri Arun

5

Kufri Kanchan

6

Kufri Lavker

qr

22.57opqr ± 0.33

s

24.87s ± 0.78

s

26.36t ± 3.57

37.35 ± 1.42

Kufri Jyoti

20

45.83 ± 1.91 47.65 ± 0.85

Scab incidence* 18.94a ± 5.25 b

Scab index* 10.18a ± 0.59

24.13 ± 2.22

10.92ab ± 0.84

20.52bc ± 5.63

11.78bc ± 1.48

bcd

± 5.36

13.21cd ± 1.17

bde

± 2.01

14.01cde ± 3.26

32.33f ± 3.37

15.46def ± 1.33

23.93 25.57

7

Kufri Badsah

31.69 ± 2.58

15.93defg ± 1.24

8

Kufri Bahar

30.25fgh ± 2.03

16.28efgh ± 1.31

9

Kufri Chipsona-1

10

Kufri Muthu

11

Kufri Chipsona-2

12 13 14

Kufri Ashoka Kufri Surya Kufri Satlaz

fg

ghi

± 2.18

17.24fghi ± 0.93

ghij

± 1.76

17.61fghij ± 1.94

28.28ghijk ± 4.07

18.19fghijk ± 3.06

27.22 29.15

fghjkl

± 1.07

18.69ghijkl ± 3.25

fghjkm

± 1.89

18.90ghijklm ± 1.33

fghjkm

± 1.63

19.32ijklmn ± 1.60

31.11 33.38 34.69

15 16


39.05 ± 0.68 38.99no ± 6.78

20.65klmno ± 2.15 21.38lmnop ± 1.28

17

Kufri Anand

43.45np ± 2.02

22.63opq ± 0.70

18 19 20

Kufri Megha Kufri Jyoti Kufri Chandramukhi

in the year 2006–2007 and 2007–2008 (Tables 3, 4). It showed again low scab index (8.40, 10.86) and incidence (16.69, 24.00) indicating least susceptibility or resistance against naturally soil inhabiting scab pathogens. Kufri Chandramukhi and Kufri Jyoti were grouped as very highly

123

10.55ab ± 1.47

12.21bcde ± 2.55

4

* Within the same column, superscripts by the same letter are not significantly different (P B 0.05) by ANOVAprotected LSD test

± 1.28

15.46

± 1.10

14

± STDV (n = 3)

9.10a ± 1.46

21.86

13

Table 2 Scab index and scab incidence of potato cultivars screened in Tikari in 2007–2008

ab

Kufri Kanchan

12


15.75a ± 3.08

Scab index*

5

9

± STDV (n = 3)

Kufri Arun

Scab incidence*

n

npq

± 1.44

22.97opqr ± 1.59

r

52.77 ± 2.89

25.16qrs ± 0.99

s

27.48s ± 2.62

45.03

57.66 ± 0.94

Class Least susceptible

Medium susceptible

Highly susceptible



Medium susceptible

Highly susceptible


susceptible cultivars based on their scab index and scab incidence recorded in the two locations for the two consecutive season 2006–2007 and 2007–2008. Among the rest nine cultivars, viz., Kufri Lavker, Kufri Badshah, Kufri Bahar, Kufri Chipsona-1, Kufri Chipsona-2, Kufri Muthu,

World J Microbiol Biotechnol (2011) 27:1559–1567 Table 3 Scab index and scab incidence of potato cultivars screened in Bachhawan in 2006–2007

S.No.

Varieties

1

Kufri Sinduri

13.40a ± 1.60 ab

Scab index* 9.96a ± 0.43

Kufri Lalima

16.69

± 2.64

8.40ab ± 0.45

3

Kufri Deva

20.15bc ± 4.10

8.98abc ± 1.23

Kufri Arun

cd

± 4.28

9.47abcd ± 1.51

bcde

24.36

5

Kufri Kanchan

21.24

± 2.16

10.94acde ± 3.06

6

Kufri Lavker

20.15bcdef ± 3.12

15.92f ± 2.31

7

Kufri Badsah

21.29

± 5.57

16.31fg ± 0.87

8

Kufri Bahar

25.16cdefgh ± 4.10

17.08fgh ± 0.62

dhi

± 2.75

18.16fghi ± 1.05

cdefghij

± 1.67

17.88fghij ± 1.71

27.89dhijk ± 1.00

15.51fghjk ± 0.85

9

Kufri Muthu

11

Kufri Chipsona-2

13 14


15 16


17

Kufri Anand

18 19 20

bcdefg

Kufri Chipsona-1

10 12


Scab incidence*

2 4

± STDV (n = 3)

1563

Kufri Megha Kufri Jyoti Kufri Chandramukhi

Kufri Ashoka, Kufri Surya and Kufri Satlaz were recorded as medium susceptible and the rest four cultivars, viz., Kufri Pushkar, Kufri Pukhraz, Kufri Anand and Kufri Megha were recorded as highly susceptible cultivars based on their scab index and scab incidence. Occurrence of phenolic compounds in potato peel HPLC analysis of peels from matured potato of twenty potato cultivars indicated that peels of potato are rich in phenolics but occurs at varied amounts (Table 5). Significant quantitative variations were observed in the profile of phenolic acids detected in the peels of the cultivars. By comparing the retention time and co-injection of the standards, 6 phenolic acids, viz., gallic, ferulic, chlorogenic, cinnamic, hydroxy cinnamic and O-coumaric acids were identified in the peels of the potato cultivars (Figs. 1, 2, 3). Appearance of the peaks was consistent in all the three samples of a single cultivar. However, quantitative estimation of the identified peaks showed significant variations in the peels of the cultivars (Table 5). Among the phenolic acids detected, gallic acid was present in peels of all the cultivars except in Kufri Chandramukhi. Its amount was maximum in peels of Kufri Sinduri (4.179 lg/g fresh wt.) followed by Kufri Chipsona-1 (3.663 lg/g fresh wt.), Kufri Lalima (3.578 lg/g fresh wt.) and Kufri Deva (3.045 lg/g fresh wt.). Minimum amount of gallic acid was found in the peels of Kufri Jyoti (1.025 lg/g fresh wt.). Hydroxy cinnamic acid was found maximum in the peels of Kufri

26.42 23.42

cdefghijl

± 4.23

15.49fghjkl ± 1.36

dhikm

± 0.35

17.76fghijkl ± 3.40

deghijklmn

± 2.07

18.48ghijmn ± 0.45

30.92 ± 2.48 33.02mop ± 3.92

22.03o ± 0.41 22.29op ± 0.91

34.70opq ± 3.42

23.06opq ± 1.58

22.32

29.14 25.98

ikmno

qr

22.57opqr ± 1.93

s

24.57pqrs ± 0.91

s

26.27s ± 0.40

38.14 ± 1.97 47.78 ± 2.81 50.24 ± 1.97


Medium susceptible

Highly susceptible


Kanchan (63.358 lg/g fresh wt.) followed by Kufri Lalima (42.715 lg/g fresh wt.) and Kufri Sinduri (36.437 lg/g fresh wt.). It was not detected in the peels of cultivars Kufri Bahar, Kufri Ashoka and Kufri Pukhraj. Hydroxy cinnamic acid was present in minimum quantity in the peels of Kufri Chandramukhi (12.274 lg/g fresh wt.). Similarly, ferulic acid was present in maximum quantity in the peels of Kufri Lalima (14.375 lg/g fresh wt.) followed by Kufri Deva (12.430 lg/g fresh wt.) and Kufri Kanchan (10.718 lg/g fresh wt.) whereas its quantity was least in the peels of Kufri Chandramukhi (0.875 lg/g fresh wt.). Ferulic acid was not detected in the peels of Kufri Lavkar, Kufri Chipsona-1, Kufri Satlaz and Kufri Megha. Chlorogenic acid was present in maximum quantity in the peels of Kufri Sinduri (24.344 lg/g fresh wt.) followed by Kufri Deva (22.240 lg/g fresh wt.) and Kufri Kanchan (10.718 lg/g fresh wt.) whereas it was present in least quantity in the peels of Kufri Jyoti (1.315 lg/g fresh wt.). It was not detected in the peels of cultivars Kufri Arun, Kufri Bahar, Kufri Muthu, Kufri Surya and Kufri Chandramukhi. O-coumaric acid was present in maximum quantity in the peels of Kufri Lalima (14.980 lg/g fresh wt.) followed by Kufri Sinduri (12.851 lg/g fresh wt.) and Kufri Deva (7.354 lg/g fresh wt.). It was present in minimum quantity in the peels of Kufri Megha (0.538 lg/g fresh wt.) and absent in the peels of Kufri Lavkar, Kufri Badshah, Kufri Muthu, Kufri Pushkar and Kufri Chandramukhi. Cinnamic acid was present in highest quantity in the peels of Kufri Sinduri (0.504 lg/g fresh wt.) followed by Kufri Deva

123

1564


Table 4 Scab index and scab incidence of potato cultivars screened in Bachhawan in 2007–2008

S.No.

Varieties

1

Kufri Sinduri

19.01a ± 7.09

Class

10.68a ± 0.87

Kufri Lalima

24.00 ± 3.28

10.86ab ± 2.26

3

Kufri Deva

20.16c ± 2.20

11.23abc ± 0.74

b

Kufri Arun

5

Kufri Kanchan

6

Kufri Lavker

bd

± 1.79

12.14abcd ± 1.12

bde

± 2.23

12.79abcde ± 2.20

28.57f ± 1.96

15.18ef ± 0.85

24.17 24.43

7

Kufri Badsah

30.06 ± 2.48

15.39fg ± 0.86

8

Kufri Bahar

27.55fgh ± 3.09

16.76fgh ± 1.64

9

Kufri Chipsona-1

10

Kufri Muthu

11

Kufri Chipsona-2

12 13 14


Scab index*

2 4

± STDV (n = 3)

Scab incidence*

fg

fghi

± 1.96

16.87fghi ± 0.94

fgij

± 1.19

17.10fghij ± 1.39

27.90fghik ± 2.73

17.48fghijk ± 1.41

gjl

± 2.27

17.84ghijkl ± 2.81

gjlm

± 3.80

18.25hijklm ± 1.73

gjlmn

± 1.77

19.07hijklmn ± 2.63

29.55

32.01


33.98 33.55 34.08

15 16


38.51 ± 1.91 39.34op ± 2.07

20.53mno ± 1.19 21.71op ± 1.28

17

Kufri Anand

40.96opq ± 2.33

22.56opq ± 1.42

Kufri Megha

r

23.31pqr ± 0.74

s

25.60rs ± 1.11

st

25.90s ± 1.05

18 19 20

no

44.32 ± 1.25

Kufri Jyoti

51.38 ± 3.49

Kufri Chandramukhi

54.38 ± 2.39

Least susceptible

Medium susceptible

Highly susceptible


Table 5 Status of phenolic acids in the peels of potato tubers of different cultivars Variety

Phenolic acids (lg/g fresh weight)* Gallic acid a

Hydroxy cinnamic acid a

Ferulic acid a

4.179

36.437

K. Lalima

3.578ab

42.715b

14.375b

20.168b

23.898

c

c

12.430

c

d

d

K. Deva

3.045

bcd

K. Arun

2.032

14.933

K. Kanchan

2.164bcde

63.354e

bcdef

df

K. Lavkar

2.005

14.061

K. Badshah

1.758cdefg

12.573fg

bcdefgh

24.344

a

K. Sinduri

abc

8.906

Chlorogenic acid

22.240

O-coumaric acid

Cinnamic acid

a

12.851

0.504a

14.980b

0.345b

c

0.416c

d

7.354

6.933

ND

2.983

ND

10.718e

21.893ce

2.620de

0.134e

f

ND

0.139ef

16.371g

ND

ND

18.242

7.972adg dgh

0.224g deh

K. Bahar

2.253

ND

7.015

ND

2.446

ND

K. Chipsona-1 K. Muthu

3.663abcdehi 1.816cdefghij

20.740i 14.473dfj

ND 2.431j

16.728gi ND

1.360ehi ND

0.066i 0.084j

K. Chipsona-2

1.142defghijk

32.208k

2.642jk

8.360k

1.126fghijk

0.108k

K. Ashoka

2.199bcdefghijkl

ND

1.501jkl

12.374l

1.702degikl

ND

K. Surya K. Satlaz

cdefghijklm

1.715

cdefghijklmn

1.526

cdefghijklmno

34.160

m

26.371

n io

K. Pushkar

1.731

20.420

K. Pukhraj

1.818cdefghijklmnop

ND

cdefghijklmnopq

dfjq

K. Anand

1.617

15.350

K. Megha

1.435cdefghijklmnopqr

16.224dqr

cdefghijklmnopqrs

dfjqs

K. Jyoti

1.025

14.172

K. Chandramukhi

ND

12.274gt

jklm

2.870 ND

ND

0.154m

fgijklmn

1.046

0.116kn ND

2.381

11.248 jklmo

dehiklm

ln

ko

1.973

7.372

ND

2.214jklmop

6.418op

1.210fghijklmnop

jklmopq

2.240

1.108

0.090jkq

ND

1.816qr

0.538fgijklmnopqr

0.118knpr

dhjmqrs

fgijklmnopq

0.128efnp

1.530

fijklnopqrs

q

fgijklmnopqrs

1.315

1.107

0.735

ND

0.875filnopqrst

ND

ND

ND

ND not detected * Means of three samples and within the same column, superscripts by the same letter are not significantly different (P B 0.05) by ANOVAprotected LSD test

123


Fig. 1 Phenolic acid profile in the peels of different potato cultivars 1 Gallic (Rt 2.89), 2 Ferulic (Rt. 3.34), 3 O-coumaric (Rt. 3.58), 4 Chlorogenic (Rt. 4.16), 5 Cinnamic (Rt. 4.54) and 6 Hydroxy cinnamic (Rt. 4.65)

(0.416 lg/g fresh wt.) and Kufri Lalima (0.345 lg/g fresh wt.) whereas it was found in least quantity in the peels of Kufri Chipsona-1 (0.066 lg/g fresh wt.). It was not detected in the peels of Kufri Arun, Kufri Bahar, Kufri Ashoka, Kufri Pushkar, Kufri Jyoti and Kufri Chandramukhi.

Discussion Scab index of the potato cultivars in both years showed very clearly the differences among the cultivars in their resistance against S. scabies. The scab index gave a clearer picture of the disease severity than the disease incidence. Several authors have screened potato cultivars against common scab (Singh and Singh 1992; Masoodi 1986; Wahid et al. 1986; Mckee 1963; Mishra and Srivastava 2001) in the past and found that in general Red skinned cultivars like Kufri Sinduri, Kufri Lalima, Kufri Arun and

1565

Fig. 2 Phenolic acid profile in the peels of different potato cultivars 1 Gallic (Rt 2.89), 2 Ferulic (Rt. 3.34), 3 O-coumaric (Rt. 3.58), 4 Chlorogenic (Rt. 4.16), 5 Cinnamic (Rt. 4.54) and 6 Hydroxy cinnamic (Rt. 4.65)

Kufri Kanchan were less susceptible to the pathogen (Singh and Singh 1992; Masoodi 1986; Mishra and Srivastava 2001). However, we observed that not only Red skinned cultivars but also some white skinned cultivars like Kufri Deva was least susceptible to the scab pathogen. In an earlier report of Mishra and Srivastava (2001), two white skinned cultivars Kufri Kundan and Kraigs Defiance were found least susceptible against S. scabies. Because of the fact that resistance may be present in both red and white skinned potato cultivars, it was often difficult to access resistance of the cultivars and requires time consuming screening procedures either at pot or field level. This necessitates development of a quick and easy method of screening resistance in the laboratory. Phenolic compounds occur in the plants either constitutively or are formed in response to pathogen ingress and considered as part of an active defense response in the host (Nicholson and Hammerschmidt 1992; Kuc 1995). The constitutive phenolics are known to confer resistance either directly (De Vecchi and Matta 1989) or indirectly through

123

1566


investigation a very clear indication was observed where resistance of the potato cultivars against S. scabies is directly correlated with occurrence of phenolic acids in the peels of the potato cultivars. The occurrence of the phenolic acids in the peels of the susceptible cultivars was either low or absent and scab index and scab incidence in those cultivars were very high. It was observed that peels of resistant cultivars possessed high amount of gallic, hydroxyl cinnamic, ferulic, chlorogenic, O-coumaric and cinnamic acids. All the red skinned cultivars belonged to least susceptible group with high amount of phenolic acids in the peels again shows a positive correlation of resistance towards the scab pathogen. Very highly susceptible cultivars Kufri Chandramukhi and Kufri Jyoti had very less amount of phenolic acids in their peels. It is important to point out here that peel of tubers is the target site of infection of the scab pathogen. Due to lesser amount of phenolic acids in the peels, those cultivars probably could not resist the attack of the scab pathogen. Thus assessment of phenolic compounds in the peels of potato cultivars can be used as a rapid technique to screen potato cultivars against the common scab pathogen S. scabies. Fig. 3 Phenolic acid profile in the peels of different potato cultivars 1 Gallic (Rt 2.89), 2 Ferulic (Rt. 3.34), 3 O-coumaric (Rt. 3.58), 4 Chlorogenic (Rt. 4.16), 5 Cinnamic (Rt. 4.54) and 6 Hydroxy cinnamic (Rt. 4.65)

References activation of post infection responses in the hosts (Harborne 1988). Certain phenolic acids such as ferulic, chlorogenic and protocatechuic acids are reported to be highly antimicrobial (Demyttenaere et al. 1997; Sarma and Singh 2003; Tamari and Kaji 1954). Many authors reported importance of phenolic compounds, carbohydrates and amino acids as biochemical markers of induction of resistance in plants against various pathogens (Nicholson and Hammerschmidt 1992; Graham et al. 1990; Singh et al. 2002a; Sarma et al. 2002); Punja (1985) reported the possibility for preventing the establishment of S. rolfsii infection through induction of impermeable layer of phenolic compounds in the host. Mandavia et al. (1997) reported that the increased concentration of salicylic acid as well as several other phenolic compounds was present in high amount in leaves and stem tissues of chickpea. Sarma and Singh (2003) observed significantly higher concentration of antifungal phenolic acids particularly ferulic acid in the collar region than in leaves of chickpea after infection which restricts the growth of S. rolfsii to the foliage of chickpea. HPLC analysis of chickpea plants revealed plant growth promoting rhizobacteria mediated alteration in phenolic compounds of the host and induced synthesis of total as well as specific phenolic acids, viz., gallic, ferulic, chlorogenic and cinnamic acids (Sarma et al. 2002). In the present

123

Bjor T, Roer L (1980) Testing the resistance of potato varieties to common scab. Potato Res 23:33–47 Collinge DB, Bryngelsson T, Gregersen PL, Smedegaard-Peterson V, Thoradal-Christensen H (1997) Resistance against fungal pathogen: its nature and regulation. In: Basra RK (ed) Mechanisms of environmental stress resistance in plants. Basra AS. London, Harwood Davis JR, Garner JG, Callihan RH (1974) Effects of Gypsum, Sulphur, Terrachlor and Terrachlor-X for scab control. Am Potato J 51:36–43 De Vecchi L, Matta A (1989) An ultra structural and cytochemical study of peroxidises, polyphenoloxidases and phenols in xylum of tomato plants infected with Fusarium oxysporum f sp. lycopersici or Fusarium oxysporum f sp. Melonis. Caryologia 42:103–114 Demyttenaere JCR, Willemen HM, Carmen Herrera MD, Verhe R (1997) Antifungal properties of essential oil components. In: Proceedings 28th International Symposium Essential oils. Eskisehir, Turkey 0–1, 1–3 September Dennis DT, Turpin DH, Lefebvre DD, Layzell DB (1997) Plant metabolism. Addition Wesley Longman, Harlow Graham TL, Kim JE, Graham MY (1990) Role of constitutive isoflavone conjugates in the accumulation of glyceollin in soybeen infected with Phytophthora megasperma. Mol PlantMicrobe Interact 3:157–166 Hahlbrock K, Scheel D (1989) Physiology and molecular biology of phenylpropanoid metabolism. Annu Rev Plant Physiol 40: 347–369 Harborne JB (1988) Introduction to ecological biochemistry, 3rd edn. Academic press, London Healy FG, Krasnoff SB, Wach M, Gibson DM, Loria R (2002) Involvement of a cytochrome P450 monooxygenase in

World J Microbiol Biotechnol (2011) 27:1559–1567 thaxtomin A biosynthesis by Streptomyces acidiscabies. J Bacteriol 184:2019–2029 Keinath AP, Loria R (1989) Population dynamics of Streptomyces scabies and other actinomycetes as related to common scab of potato. Phytopathol 79:681–687 King RR, Lawrence CH, Clark MC, Calhoun LA (1989) Isolation and characterization of phytotoxins associated with Streptomyces scabies. J Chem Soc Chem Commun 13:849–850 King RR, Lawrence CH, Clark MC (1991) Correlation of phytotoxin production with pathogenicity of Streptomyces scabies isolates from scab infected potato tubers. Am Potato J 68:675–680 King RR, Lawrence CH, Calhoun LA (1992) Chemistry of phytotoxins associated with Streptomyces scabies, the causal organism of potato common scab. J Agric Food Chem 40:834–837 Kuc J (1995) Induced systemic resistance—An overview. In: Hammerschmidt R, Kuc J (eds) Induced resistance to disease in plants. Kluwer Publishers, Amsterdam, pp 169–175 Lawrence CH, Clark MC, King RR (1990) Induction of common scab symptoms in aseptically cultured potato tubers by the vivotoxin, thaxtomin. Phytopathol 80:606–608 Lazarovits G, Tenuta M, Conn KL (2001) Organic amendments as a disease control strategy for soil born diseases of high value agricultural crops. Australas Plant Pathol 30(2):111–117 Lehtonen MJ, Rantala H, Kreuze JF, Ba˚ng H, Kuisma L, Koski P, Virtanen E, Vihlman K, Valkonen JPT (2004) Occurrence and survival of potato scab pathogens (Streptomyces scabies) on tuber lesions: quick diagnosis based on a PCR-based assay. Plant Pathol 53:280–287 Loria R, Bukhalid RA, Fry BA, King RR (1997) Plant pathogenicity in the genus Streptomyces. Plant Dis 81:836–846 Loria R, Bignell DRD, Moll S, Jose C, Tapia H, Joshi MV, Johanson EG, Seipke RF, Gibson DM (2008) Thaxtomin biosynthesis: the path of plant pathogenicity in the genus Streptomyces. Antonie van Leeuwenhoek 94:3–10 Madamanchi NR, Kuc J (1991) Induced systemic resistance in plants. In: Cole GT, Hoch HC (eds) The fungal spore and disease initiation in plants and animals. Plenum Press, New York, pp 347–362 Mandavia MK, Patel CM, Maravia GV, Parameswaran M (1997) Role of phenolic compounds in resistance to Fusarium with in chickpea. India J Agric Biochem 10:11–13 Marais L, Vorster R (1988) Evaluation in pot and field trials of resistance of potato cultivars and breeding lines to common scab caused by Streptomyces scabies. Potato Res 31:401–404 Masoodi SD (1986) Pathological studies on common scab of potato caused by Streptomyces spp. Ph.D. thesis. CSAUA&T, Kanpur, pp 214 Mc Rae W (1929) India: new plant diseases reported during the year 1928. Int Bull Plant Protect III:21–22 Mckee RK (1963) Scab resistance of potato varieties. Plant Pathol 12:106–109 Mishra KK, Srivastava JS (1999) Severity of prevalence of common scab of potato in Eastern U. P. Indian Potato J 26:23–24

1567 Mishra KK, Srivastava JS (2001) Screening potato cultivars for common scab of potato in naturally infested field. Potato Res 44:19–24 Mishra KK, Srivastava JS (2005) Soil amendments to control common scab of potato. Potato Res 47:101–109 Nagaich BB (1983) Disease resistance in potato in India. Indian Phytopath 36(1):1–10 Neeno-Eckwall EC, Kinkel LL, Schottel JL (2001) Competition and antibiosis in the biological control of potato scab. Can J Microbiol 47(4):332–340 Nicholson RL, Hammerschmidt R (1992) Phenolic compounds and role in disease resistance. Annu Rev Phytopathol 30:369–389 Paharia KD, Pushkarnath (1963) Occurrence of potato scab in Bihar. Indian Potato J 5:104–105 Punja ZK (1985) Biology, ecology and control of Sclerotium rolfsii. Annu Rev Phytopathol 23:97–127 Sarma BK, Singh UP (2003) Ferulic acid may prevent infection of Cicer arietinum by Sclerotium rolfsii. World J Microbiol Biotechnol 19:123–127 Sarma BK, Singh DP, Mehta S, Singh HB, Singh UP (2002) Plant growth-promoting rhizobacteria-elicited alterations in phenolic profile of chickpea (Cicer arietinum) infected by Sclerotium rolfsii. J Phytopathol 150:277–282 Sharma KD (1984) Studies on common scab of potato. Ph.D. thesis. GB Pant Univ Agri and Tech Pantnagar, Nainital Singh A, Singh DV (1992) Source of resistance to common scab of potato. Indian Phytopath 45:225–226 Singh UP, Sarma BK, Singh DP, Bahadur A (2002a) Plant growthpromoting rhizobacteria-mediated induction of phenolics in pea (Pisum sativum) following infection with Erysiphe pisi. Curr Microbiol 44:396–400 Singh UP, Sarma BK, Singh DP, Bahadur Amar (2002b) Studies on exudates-depleted sclerotial development and effect of oxalic acid, sclerotial exudates and culture filtrate of Sclerotium rolfsii in induction of phenolic acids in chickpea (Cicer arietinum). Can J Microbiol 48:443–448 Singh UP, Sarma BK, Singh DP (2003) Effect of plant growthpromoting rhizobacteria and culture filtrate of Sclerotium rolfsii on phenolic and salicylic acid contents in chickpea (Cicer arietinum L.). Curr Microbiol 46:131–140 Steel RGD, Torrie JH (1980) Principles and procedures of statistics: a biometric approach. Mgcraw-Hill, New York Tamari K, Kaji J (1954) Biochemical studies of the blast fungus Pyricularia oryzae cav., the causative fungus of the blast disease of the rice plants–I: studies on the toxins produced by blast fungus. J Agric Chem Soc Japan 29:185–190 Wahid SA, Ahmed R, Muhammad S (1986) Common scab (Streptomyces scabies) on potato in Pakistan. J Agric Res 22:269–271 Waterer D (2002) Impact of high soil pH on potato fields and grade losses to common scab. Can J Plant Sci 82(3):583–586

123