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B - METABOLIC STUDIES

All various macroscopic and microscopic symptoms of diseases must originate in

biochemical aberrations induced directly or indirectly by the viruses (Matthews, 1970). Virus

pathogen interaction since no metabolic activity has been associated with isolated plant viruses.

The visible symptoms induced in plant tissues infected by viruses and observed in the

form of mosaic, chlorosis, rings, necrosis, necrotic spots, curl, tumours etc. are manifestations of

disturbances in host metabolism.

Murphy and Colucci (1999) reviewed Lablab purpureus. Biswas and Varma (2000)

identified variants of mungbean yellow mosaic geminivirus by host reaction and nucleic acid

spot hybridization. Pant et al. (2001) reported molecular characterization of the red protein of the

black gram isolate of Indian mungbean yellow mosaic virus. Two newly Begomoviruses of

Macroptilium lathyroides and common bean was described by Idris et al. (2003). Barhate et al.

(2003) evaluated the response of urdbean genotypes to powdery mildews, leaf curl, and yellow

mosaic disease. Yellow mosaic virus infecting, soybean in northern India is distinct than

southern and western India was studied by Usharani et al. (2004). Current status of

begomoviruses in the Indian subcontinent was reported by Rishi (2004). Cloning, restriction

mapping and phylogenetic relationship of genome components of MYMIV from Lablab

purpureus was studied by Singh et al. (2005).

Various authors have reviewed biochemical changes in virus-infected plants as compared

to healthy ones (Erdiller and Ozyanar 1983, Palilova et al. 1990, Srinivasulu and Jeyrajan 1990,

Hossain and Haider 1992, Thind et al. 2005, Muqit et al. 2007, Sinha and Srivastava, 2010).

In India physiology of virus-infected plants is limited to following viral diseases such as

dolichos enation mosaic (Rajagopalan and Raju 1972), pigeon pea sterility mosaic

(Narayanswamy and Ramakrishnan 1966 ‘a’ and ‘b’, Nambiar and Ramakrishnan 1969), mosaic

of chilli (Jeyarajan and Ramakrishnan 1968, 1972), cowpea mosaic (Khatri and Chenulu 1973),

common bean mosaic (Chowdhury and Srivastava 1986), yellow vein mosaic of okra (Ramiah et

al. 1972, Singh and Srivastava 1974 b), potato virus X (Singh and Mall 1974 a), urdbean mosaic

(Singh and Srivastava 1985), pumpkin mosaic (Ghosh and Mukhopadhyay 1980, Singh 1983 ‘a’

and ‘b’ ), cucumber mosaic (Sharma et al. 1980, Hemida 2002), rice tungro virus disease

(Mohanty and Sridhar, 1989). Hemida (2005) reported effect of Bean yellow mosaic virus on

physiological parameters of Vicia faba and Phaseolus vulgaris.

Chlorophyll Content:

Chlorophyll, the green pigment of plants, is the most important component of the

photosynthetic system. In plants, virus infection induces change in the colouration of leaves, a

number of them showing mosaic or related symptoms. Virus infection frequently involves the

colour change in most of the plants, shows that chlorophyll content is either not synthesized at

the same rate as in healthy plants or some amount of chlorophyll is destroyed as a consequence

of infection.

The loss of chlorophyll in such cases has been attributed to the inhibition of the formation

of new plastid units after virus infection rather than their destruction reported by (Diener, 1963;

Goodman et al. 1967; Ramakrishnan et al. 1969; Singh and Mall, 1973; Singh and Srivastava,

1979 and Sharma et al. 1980). Reduction in chlorophyll content has been reported in many host

plants infected with different viruses, such as Dolichos enation mosaic infected with DEMV

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Review of Literature

(John, 1963 a), virus infected leaves of Cucurbita pepo, Abelmoschus esculentus and Glycine

max. (Ramiah et al. 1972). The amount of chlorophyll, chlorophyll a and b in infected leaves

were lower than in controls in muskmelon leaves infected by CMV (Sharma et al. 1980).

El- Shaieb et al. (1981) observed that BBTMV infection of broad bean plant lowers the

chlorophyll content in the leaves. Gupta and Chowfla (1987) found that infection of bean

common mosaic virus reduced the chlorophyll content in some varieties of Phaseolus. In a study

on physiological effects of bean common mosaic virus in French bean (Phaseolus vulgaris L.)

Suresh et al. (1988) reported reduction in chlorophyll contents in pods of infected plants than the

healthy ones. Similarly, it was found by Ravinder et al. (1989) that French bean (Phaseolus

vulgaris L.) plants infected by bean common mosaic virus lesser chlorophyll contents in their

leaves. Hashmathunnisa and Madhusudan (1989) observed less chlorophyll content in

Cyamopsis tetragonoloba infected with cluster bean mosaic virus. Pandey and Joshi (1989)

accounted less chlorophyll content and less number of chloroplasts and increase chlorophyllase

activity in infected leaves of Momordica charantia, infected with Cucumus Virus-3.

Kaur et al. (1991) found similar results in soyabean leaves infected with soyabean mosaic

virus. Sarma et al. (1995) noticed reduction in chlorophyll (total ‘a’ and ‘b’) contents in infected

leaves of bhindi due to infection with yellow vein mosaic virus. Dantre et al. (1996) pointed out

decreased chlorophyll (total ‘a’ and ‘b’) contents in leaves of soybean infected with yellow

mosaic virus. Sultana (1998) found lesser amount of total chlorophyll, chlorophyll a, and

chlorophyll b whereas lesser amount of carotenoid in diseased plant of Vigna unguiculata due to

infection with yellow mosaic virus. Bianchini et al. (1998) reported reduced chlorophyll content

in the infected plants of Phaseolus vulgaris L. due to infection of bean golden mosaic virus.

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Mali et al. (2000) found reduction in chlorophyll (a and b) in diseased plants of moth

bean genotype infected with yellow mosaic virus. Bassanezi et al. (2001) observed reduction in

chlorophyll content in leaves of Phaseolus vulgaris L. infected with bean line pattern mosaic

virus. Lower chlorophyll content and higher carotenoid to chlorophyll ratio than those in intact

and mock-inoculated controls – signs of senescence – were observed in leaves with local lesions

and in yellow leaves of infected plants (Mojca 2001). Malik et al. (2002) reported enhanced total

chlorophyll content in Vigna mungo L. var. T 9 infected by urd bean leaf crinkle virus.

Various metabolites of host tissue were altered due to viral infection as reported by

(Naidu et al. 1986; Srinivasulu and Jeyarajan 1990; Chakraborty et al. 1994; Clover et al. 1999;

and Hemida and Abdel-Razik 2002). Pigment content (chlorophylls a, b and carotenoids), water

soluble carbohydrates, total soluble proteins and total free amino acids were estimated in leaves

of two host plants (Vicia faba and Phaseolus vulgaris) inoculated with BYMV for 4, 12 and 20

days.

The TMV infection slightly changed total chlorophyll, phenolic antioxidant compounds

and soluble protein in infected plant. The TMV infection leads to a decrease in chlorophyll a + b,

total phenols and soluble protein by rate 47.89%, 7.89% and 61.35% in infected leaves. As well

as increase in the phenolic antioxidant compounds in infected leaves (Dina et al. 2008). The total

chlorophyll, chlorophyll a, chlorophyll b and carotenoid content were lower in infected tissue

(Singh and Shukla, 2009).

Total chlorophyll, chlorophyll a, chlorophyll b content was lower in virus infected

mungbean plant varieties and hyacinth bean (Sinha and Srivastava, 2010, Srivastava et al. 2012).

The study was conducted to elucidate the diverse change in the amount of pigment contents in

four varieties of the virus infected tomato plants. viz. Laxmi (NP-5005), Kranti, Priya and Sartaj-

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plus. The infected leaves and fruits were collected after 15, 30 and 45 days of infection. The

changes in pigment content viz. chlorophyll a, chlorophyll b, Total chlorophyll, lycopene and β-

carotene were measured to quantify the changes in pigments content (Raithak and Gachande,

(2012). Viral infection (singly or doubly) caused irregular changes in nutrient elements values of

both (bean and broad bean common cultivars) hosts compared with healthy ones (Tahmasebi et

al. 2013).

Protein Content:

Virus multiplication in plants generally causes synthesis of abnormal proteins resulting in

an alteration in type and the amount of total proteins. Stanley (1937) noticed two to three times

more protein nitrogen in tobacco plants infected with tobacco mosaic virus or aucuba mosaic

virus but tobacco plants infected with masked tobacco mosaic, green or yellow cucumber

mosaic, severe etch tobacco ringspot and latent mosaic viruses showed decrease in protein

content due to mosaic infection of tobacco plants.

Harris et al. (1970) noticed that early infection of soybean with cowpea chlorotic virus

increased total protein content. Akhatova (1972) noticed a reduction of 6.44 and 4.31 percent in

protein content of green tissues and seeds respectively of soybean mosaic virus infected soybean.

Gradual increase in the protein content was observed by Shukla et al. (1984) throughout

the experimental period in leaf, stem and root of bean common mosaic virus infected French

bean plants. Suresh et al. (1988) found higher protein content in Phaseolus vulgaris L. infected

with bean common mosaic virus.

Gupta (1990) noticed increase protein content in root nodules of soybean mosaic virus

infected soybean (Glycine max L. Merr.). Kaur et al. (1991) also reported increased protein


content in soybean plants due to soybean mosaic virus infection. Lu and Chen (1994) noticed

higher protein content in soybean plants infected with soybean mosaic virus. Singh (1995)

observed increased protein content in leaves, stems and roots of pea plants infected with bean

yellow mosaic virus. An increased protein level in virus-infected plants has also been reported in

several cases by previous workers Chakraborty et al. (1995). Zheng and Gao (1998) reported

higher protein content in soybean seed infected with soybean mosaic virus.

Mali et al. (2000) found protein content increased with increasing level of yellow mosaic

virus infection in moth bean Vigna accnitifolia genotype. Bhagat and Yadav (2005) studied

biochemical changes induced by Bhindi yellow vein mosaic virus (BYVMV) infection in leaves

of resistant ‘Parbhani Kranti’, susceptible ‘Vaishali Vadhu’ and highly susceptible ‘Pusa Sawani’

bhindi cultivars, total soluble protein content was increased in infected leaves at all stages of

growth.

Singh and Shukla (2009) reported nitrogen and protein contents were higher in infected

tissue of Carica papaya L. infected by PRSV compared to healthy counterparts.

Sinha and Srivastava (2010) reported protein content increased in virus infected

mungbean leaves. Ashfaq et al. (2010) studied increased total soluble protein contents at 15 and

30 days after inoculation in both susceptible and resistant plants infected by ULCV. The BYMV-

infected bean leaves had protein contents higher than the control (Mohammed et al. 2010).

The levels of proteins were significantly higher in CMV infected tomato plants compared

to the control (Maria Kalogirou, 2012). Srivastava et al. (2013) found that total protein content

was found to be high in virus infected Dolichos lablab L. crop at 60th days interval.

Nitrogen Content:


There are reports of both increased as well as decreased nitrogen content due to virus

infections. Harman et al. (1970) in mosaic infected tobacco leaf, Tu et al. (1970 a) in nodules of

soybean mosaic virus infected soybean plants. Jeyarajan and Ramakrishnan (1972) in chilli

plants infected with potato virus Y. Rajagopalan and Raju (1972) in field bean infected with

dolichos enation mosaic virus. Khatri and Chenulu (1973) were pointed out an increase in total

nitrogen content due to infection of cowpea mosaic virus infected cowpea plants respectively.

Other reports of increased nitrogen content include those of Mali et al. (1977) in soybean plants

infected with alfalfa mosaic virus, Singh et al. (1978) in cowpea leaves infected by Southern

bean mosaic virus. Ramapandu and Raychaudhuri (1978) found that in case groundnut plants

infected with the bud necrosis virus the total nitrogen content decreased in leaves and increased

in stem and root.

Gupta (1990) reported more nitrogen content in nodule of soybean (Glycine max L.

Merr.), infected with soybean mosaic virus. Lu and Chen (1994) found increase total nitrogen

content in soybean plant infected with soybean mosaic virus. Singh (1995) observed higher

nitrogen content in leaves, stems and roots of pea plants infected with bean yellow mosaic

potyvirus. Sarma et al. (1995) noticed increased total nitrogen content in leaf of bhindi

(Abelmoshcus esculentus L. moench) plants infected with yellow vein mosaic virus. Chakraborty

et al. (1995) and Thind et al. (1996) reported general increase of the total nitrogen in virus

infected plants for a number of host. Consequently, the established higher total protein content

was more likely to be due to the increased level of viral proteins in the plant.

Verma and Gupta (2008) reported that the total nitrogen content in leaf, stem & root of

virus-infected samples was higher than that of healthy ones. The gradual increase in total

52


nitrogen content was observed throughout the experimental period in healthy and diseased

plants.

Sinha and Srivastava (2010) reported total nitrogen (N) content are higher in the virus-

infected plants in all 3 varieties viz., HUM-2 (Malviya Jagriti), ML-192 and Pusa Baisakhi

infected by Mungbean yellow mosaic virus. Nitrogen content was found to be high in virus

infected Dolichos lablab L. crop at 60th days interval (Srivastava et al. 2013).

Phenolic Content:

Phenolic acids play an important role in the development of resistance in plants through

biochemical changes in cell environment (Agrios, 1997).

Premchand and Verma (1980) noticed more phenol content in yellow mosaic virus

infected urd bean and mung bean leaves. Sastry and Nayudu (1988) observed increased amount

of phenolic compounds in cowpea leaves infected with tobacco ring spot virus.

Kofalvi and Nassuth (1995) reported significant increase in phenol accumulation in

wheat plants infected with the wheat streak mosaic potyvirus (WSMV) compared to the healthy

controls. Dantre et al. (1996) reported increased total phenol in yellow mosaic virus infected

soybean leaves and seeds. Sultana et al. (1998) observed that the phenolic contents were higher

in the infected plants of Vigna unguiculata due to the infection of yellow mosaic virus than in the

healthy ones.

Mali et al. (2000) recorded total phenols increased with increasing levels of yellow

mosaic virus infection in moth bean genotypes. Malik et al. (2002) reported decrease total phenol

content in Vigna mungo L. var. T 9 infected by urd bean leaf crinckle virus but var. PU 35 was

found to be moderately resistant to ULCV and exhibited high total phenols. Balogun and

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Teraoka (2004) reported the cotyledons of 3 –true leaf potted seedlings of a common Japanese

tomato (i.e. cv. Fukuju No. 2) were mock inoculated with buffer only or singly and doubly with

potato Virus X (PVX) and/or an attenuated strain (L11A) of tobacco mosaic virus (TMV-L11A)

in greenhouse experiments. Viral infection not only affected the quantity but may also have

altered the type of phenol components of the infected tomato plants.

Bhagat and Yadav (2005) studied phenol content were increased in infected leaves at all

stages of growth over healthy were more in the ‘pusa sawani’ as compared to ‘vaishali vadhu’

and ‘parbhani kranti’ infected by Bhindi yellow vein mosaic virus (BYVMV). Khan et al. (2005)

investigated the impact of the leaf curl disease caused by a begomovirus on capsaicinoids content

in diseased fruits of six cultivars of hot pepper. The protein, total phenols, antioxidant and free

radical scavenging activities were also found higher in the diseased fruits than that of healthy.

Rishi et al. (2008) investigated changes in phenols (total and o-dihydroxy phenols) and enzymes

like peroxidase due to the infection of geminivirus. Total phenol was significantly high in

diseased leaf as compared to healthy leaf. The increased quantity of total phenol might be

attributed to defence mechanism. The resistance to disease caused by pathogen was attributed to

the presence of high amount of phenol (Dina et al. 2008). Hence, the increased quantity of

phenolics in the infected plant parts of the chilli may be contributing to the resistance against

pathogen (viral infection).

Mohammed et al. (2010) noticed an increase in the amounts of phenolics and

flavonoids due to viral infection. Raithak and Gachande (2012) observed reduced phenol content

in virus infected tomato plant. Diseased leaf showed more phenol (0.51) compared to healthy

(0.33) whereas not much difference was observed between healthy (0.68) and diseased leaf

(0.71) in case of resistant genotypes DCS-6 at 30 days after sowing (Shilpashree et al. 2013).


Amino Acid content:

Tu and Ford (1970) got an increase in free amino acid contents in soybean plants infected

with three soybean mosaic virus isolates and bean pod mottle virus or both. Individual amino

acids decreased, however, or were variable depending on soybean mosaic virus isolates. Free

amino acid content appeared closely related with severity. Gupta and Joshi (1976) while working

on the free amino acids content in the nodules of soybean plants infected with soybean mosaic

virus found increased concentration of free amino acids in the nodules of diseased plans in

comparison to healthy ones.

Omar et al. (1986) found that the concentration of free amino acids in infected leaves and

seeds differed according to the virus, host plants (soybean, bean and lettuce) and duration of

sampling. Kaur et al. (1991) observed lower percentage of free amino acids in seeds of infected

soybean plant with yellow vein mosaic virus. Lu and Chen (1994) reported increased total free

amino acids in soybean plants infected by soybean mosaic virus. Singh (1995) pointed out that

the total free amino acids were higher in leaves, stems and roots of pea plants infected with bean

yellow mosaic potyvirus than in the healthy plant parts. Dantre et al. (1996) reported total amino

acid, were increased in infected leaves and seeds of soybean infected with yellow vein virus.

Zheg and Gao (1998) observed that amino acid content increase in susceptible varieties

and decreased or remained stable in resistant varieties of soybean after soybean mosaic virus.

Sutha et al. (1998) found increased amino acid contents in tospovirus infected tomato plants in

compared to the healthy ones.

Mali et al. (2000) recorded free amino acids increased with increasing level of yellow

mosaic virus infection in susceptible variety of moth bean genotypes.

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Hemida (2005) estimated total free amino acids in leaves of two host plants (Vicia faba

and Phaseolus vulgaris) inoculated with BYMV for 4, 12 and 20 days. In Phaseolus vulgaris,

pigment contents, carbohydrates and free amino acids were decreased with time. Strategy of

defense mechanism in each host plant against BYMV infection was varied.

According to Bhagat and Yadav (2005) studied free amino acid decreased in the infected

leaves of ‘Pusa Sawani’ as compared to Parbhani Kranti’, susceptible ‘Vaishali Vadhu’ by

Bhindi yellow vein mosaic virus (BYVMV).

Verma and Gupta (2007) reported that the Bean common mosaic virus infection

influenced the concentration of free amino acid in French bean plant. The disease plant has

higher concentration of free amino acid than the healthy plant. In general, there was an increase

in the concentration of different amino acid with the age of plant. The levels of free amino acids

were significantly higher in CMV infected tomato plants compared to the control (Maria

Kalogirou, 2012). Amino acid content was found to be high in virus infected Dolichos lablab L.

crop at 60th days interval (Srivastava et al. 2013).

Carbohydrate content:

Changes (either an excessive accumulation or depletion) in the carbohydrate content have

been reported for several different types of plant hosts infected with different viruses.

Rajagopalan and Raju (1972) observed that dolichos enation mosaic virus caused an

increase in carbohydrate content in roots and decrease in its shoots under symbiotic conditions,

but during early growth after virus inoculation carbohydrate content was increased in both roots

and shoots.

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Singh and Mall (1978) reported that the various carbohydrate fractions were higher in

healthy pigeon pea fruits than in infected plants due to arhar mosaic virus infection. Ghosh

(1979) in Lagenaria vulgaris leaves showed that the decrease in reducing sugar was maximum

40 days after inoculation and the starch content increased at the beginning of infection but

decreased later due to bottle gourd mosaic virus. Singh and Mall (1979) in pigeon pea leaves

infected with arhar mosaic virus observed decrease in total carbohydrate content of the plants.

Ghosh and Mukhopadhyay (1980) noticed a general increase in reducing sugar content

and decrease in starch content in pumpkin plants infected by some anisomeric cucurbit viruses.

Sindelar et al. (1980) found decreased starch and sugar contents in leaves of cucumber mosaic

virus infected cucumber plants. Ravinder et al. (1989) reported that the reducing sugar, non-

reducing sugar, starch content and total carbohydrate content were significantly decreased in

BCMV infected leaves of Phaseolus vulgaris.

Dantre et al. (1996) reported decrease of reducing sugar, non - reducing sugar and total

sugar in yellow vein mosaic virus infected soybean (Glycine max L. Merr.). Sultana et al. (1998)

found that the higher amounts of total sugar, reducing sugar and non – reducing sugar in Vigna

unguiculata L. than in infected plants due to the infection of yellow mosaic virus.

Mali et al. (2000) observed increase total soluble carbohydrate and starch in healthy moth

bean genotype than the infected ones due to the infection of yellow mosaic virus. Shalitin and

Wolf (2000) determined the effect of cucumber mosaic virus (CMV) infection on sugar

transport, carbohydrate levels and the amounts of the various sugars in the phloem sap in

infected melon (Cucumis melo L.) plants. Source leaves infected with CMV were characterized

by high concentrations of reducing sugars and relatively low starch levels. Malik et al. (2002)

reported enhanced total starch content in Vigna mungo L. var. T 9 infected by urd bean leaf

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crinkle virus. Gonçalves et al. (2005) reported infection by Sugarcane yellow leaf virus (ScYLV)

causes severe leaf symptoms in sugarcane (Saccharum spp.) hybrids, which indicate alterations

in its photosynthetic apparatus. Carbohydrate content in the leaves was increased as a secondary

effect of the ScYLV infection.

Leher et al. (2007) reported the carbohydrate concentration in leaves of young, 6 months

old plants was much lower than in mature plants and it increased to 500% during day time in

sugarcane plants infected by sugarcane yellow leaf virus. Asymptomatic leaves had a higher

level of carbohydrates, especially starch, from late afternoon until the end of the night,

suggesting a reduction of assimilates export.

Michael et al. (2007) investigated infection of Arabidopsis thaliana with Turnip vein-

clearing virus, Cucumber mosaic virus or Cauliflower mosaic virus in plants grown under

continuous illumination (under which there is no net breakdown of starch) and in pgm1 mutant

plants lacking chloroplastic phosphoglucomutase, an enzyme required for starch biosynthesis.

Virus-infected wild-type plants grown under continuous light exhibited more severe leaf

symptoms, but no reduction in growth compared with plants grown under diurnal illumination.

Goodman et al. (2008) studied Carrot motley dwarf virus increased fructose, glucose and

sucrose concentrations in carrot leaves, but in petioles and roots sucrose increased while fructose

and glucose decreased: more sugar accumulated in plants infected late than early. Cereal yellow

dwarf virus (CYDV) increased fructose, glucose, sucrose and four fructosans in leaves of oats,

an avirulent strain more than a virulent one. Virulent strains of BYV and CYDV apparently

decrease photosynthesis more than avirulent ones.

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Singh and Shukla (2009) found the carbohydrate content was lower in infected tissue

(11.4%, 9.3% & 8.2% for reducing sugars, non-reducing sugars & starch, respectively) in Carica

papaya L. infected by PRSV.

Gupta et al. (2010) observed the carbohydrate (reducing sugar, non-reducing sugar and

starch) content of nodules in soybean mosaic virus infected soybean indicated the reduction of all

the contents in comparison to nodules in the healthy plants. The results were significant in the

case of non-reducing sugar. Sinha and Srivastava (2010) reported carbohydrate content were

lower in virus infected mungbean plant varieties infected by Mungbean yellow mosaic virus. The

levels of reducing sugars were significantly higher in CMV infected tomato plants compared to

the control (Maria Kalogirou, 2012). Raithak and Gachande (2012) observed reduced content of

carbohydrate in virus infected tomato plant.

Leghaemoglobin:

The leghaemoglobin pigment present in nodules plays an important role in the process of

nitrogen fixation.

Tu et al. (1970a) reported that the nodules of healthy soybean plants had higher

leghaemoglobin contents than those infected with soybean mosaic virus. Rajgopalan and Raju

(1972) found that the formation of leghaemoglobin in nodules of Dolichos lablab L. was not

affected by Dolichos enation mosaic virus. The peak concentration of the pigment, however, was

attained earlier in nodules of infected plants than those of virus free ones. The nodules on DEMV

–infected plants were larger, as also found for soybeans growing in a sand-peat-loam soil

mixture and infected with SMV and bean pod mottle virus (Tu et al. 1970b). Tu and Tse (1976)

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found the greater numbers of rhizobia were required in order to produce similar numbers of

nodules on soybeans infected with AMV to those on healthy plants.

Srivastava (1982) also observed lesser amount of leghaemoglobin in Sesbania infected

with Sesbania mosaic virus. Tripathi (1985) observed similar findings in cowpea vein banding

mosaic virus infected cowpea plants. Rao et al. (1987) and Rao and Shukla (1988) reported

lesser leghaemoglobin content in pea root nodules infected with cucumber mosaic virus and

Sesbania mosaic virus, respectively. Sharma and Varma (1988) observed similar results, wherein

leghaemoglobin content was reduced by cowpea chlorotic spot virus infection of cowpea plants.

Patil and Sayyad (1991) undertook the study of leghaemoglobin content in cowpea

nodules as influenced by virus Rhizobium interactions. They reported that virus infection reduced

the leghaemoglobin content substantially. In a similar study on Vigna sinensis, grown in three

different culture media, Upadhyaya et al. (1991) found that cowpea vein banding mosaic virus

affected the leghaemoglobin content adversely. Srivastava (1991) found that leghaemoglobin

content was reduced in nodules of Sesbania sesban infected with Sesbania mosaic virus.

Gross reduction of nodulation was achieved by virus inoculation on broad bean plants cv.

Giza 402. It produced smaller, fewer nodules and reduced its leghaemoglobin content. This

difference was accompanied with the presence of BBSV particles in the root nodule cells

(Mamdouh et al. 2011). Nodules of healthy plants have higher leghaemoglobin content than

those of virus infected hyacinth bean (Srivastava et al. 2013).

Catalase:

Although, alteration in the activity levels of enzymes have been observed with a number

of plant virus diseases but none of these observation appear to have precise correlation with the

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course of virus multiplication. However, certain results may afford partially in explaining the

appearance of particular disease symptoms. It has been conjectured from the differences that

virus infection alters enzyme activity. Orlob and Arny (1961) reported decreased catalase

activity in leaves of barley plant infected with barley yellow dwarf virus. Jeyarajan and

Ramakrishnan (1968) observed lesser catalase activity in chilli plants infected with potato virus

Y in comparison to healthy ones. Joshi and Gupta (1980) noticed lesser catalase activity in root

nodules of soybean infected with soybean mosaic virus.

Fodor et al. (1997) found no changes in tobacco infected by TMV or rather a decrease in

CAT activity in apricot infected by plum pox virus (Hernández et al. 2001). Clarke et al. (2002)

reported that CAT activity was significantly decreased in P. vulgaris infected with WClMV and

in tobacco plants infected with TMV (Chen et al. 1993; Neuenschwander et al. 1995).

A decrease in catalase activity was also described in PPV-infected apricot leaves

Herna´ndez et al. (2006) and in Tobacco mosaic virus (TMV)-infected Nicotiana glutinosa L.

plants Yi et al. (1999). Yi et al. (1999) showed that catalase activity and transcripts (Ngcat1 and

cat2) declined in TMV infected hypersensitive lesions in tobacco and suggested that catalase

activity was regulated at the transcriptional level following infection with an incompatible

pathogen. TMV infection transiently reduces the transcript level of Ngcat1 and total catalase

activity in tobacco leaves (So- Young et al. 2003).

Doubnerová et al. (2007) showed the changes in the antioxidant enzyme activities at

early stages of the infection were insignificant particularly in the transgenic P3 plants infected

with PVYNTN. The only exception was CAT activity which was 5-fold higher in the PVYNTN

infected SR1 already 24 h after inoculation and 1.5-fold higher in the infected P3 plants

compared to the healthy plants.

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Petrova et al. (2009) investigated two lines (Okal and L57) of Capsicum annuum with

different susceptibility to Cucumber mosaic virus (CMV) and influence of pathogenesis on

peroxidase and catalase activities, carotenoid content and symptom appearance. The decrease of

CAT activity was recorded after 17th day in the systemic leaves of L57. The both leaves of Okal

infected by CMV showed similar developed of CAT activity like control plants.

Ashfaq et al. (2010) reported that there was no significant change in catalase activities in

ULCV infected and control plants of both susceptible and resistant cultivars in blackgram (Vigna

mungo L. Hepper). Srivastava et al. (2012) studied bean common mosaic virus influenced the

catalase activity in healthy and diseased hyacinth bean leaves at different intervals of time.

Peroxidase:

Different workers have indicated possible changes in peroxidase activity in host plant due

to virus infection. Loebenstein and Linsey (1961) showed that peroxidase activity in vein

clearing virus infected leaves and roots of sweet potato were significantly higher than healthy

ones. The increase in peroxidase activity commenced with the appearance of symptoms. The

activity varied with the age of leaf and period of infection.

Kuprevich et al. (1966) reported increased peroxidase activity in leaves of common pea

mosaic virus affected broad bean. Chant (1967) working with tobacco necrosis virus

mechanically inoculated on French bean observed greater peroxidase activity in comparison to

healthy ones. Ramakrishnan et al. (1969) also noticed increased peroxidase activity in pigeon

pea sterility mosaic virus infected pigeon pea.

Rathi et al. (1986) also reported non-involvement of PO and PPO in imparting resistance

to pigeonpea against sterility mosaic virus. Lagrimini and Rothstein (1987) determined the effect

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of TMV infection on the induction of peroxidase isozymes. Enhanced PO activity has frequently

been correlated with symptom severity.

Van Loon (1976) and Nadlong and Sequeira (1980) suggested that the increased PO-

activity following virus infection was a reflection of physiological changes associated with, but

not responsible for induced resistance whereas up-regulated peroxidases might be responsible for

growth reductions and malformations in virus-infected plants (Riedle, 1998). PO participates in a

variety of plant defense mechanisms (Mareschbacher et al. 1986) in which H2O2 is often

supplied by an oxidative burst, a common event in defense responses (Dixon and Lamb, 1990).

Miteva et al. (2005) studied the influence of arsenic and Cucumber mosaic virus (CMV),

applied separately and simultaneously on young tomato plants. Virus infection induced stronger

specific peroxidase activity (SPOA) than arsenic treatment. At all stages of sampling non-

significantly higher PO activity was observed in healthy leaves of susceptible (Mash-88)

genotype than in the resistant one. The activity of PO increased with the passage of time in both

the genotypes but ULCV inoculation resulted in significant increase of total PO activity in

resistant cultivar after 15 (p<0.05) and 30 (p<0.05) days of inoculation, whereas the increase

remained non - significant in the diseased leaves of the susceptible one. The enhancement of PO

might be responsible for the activation of resistance mechanism in virus-infected plants. Clarke

et al. (2002) and Karthikeyan et al. (2007) observed significant increase in peroxidase activity in

P. vulgaris and V. mungo plants after inoculation with WClMV and ULCV, respectively.

Peroxidase activity and isozyme patterns were investigated in two leguminous species

infected with viruses, which produced either local necrotic or systemic chlorotic symptoms.

Highest peroxidase activity was recorded when the hosts reacted to infection with necrotic local

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lesions. Increase in peroxidase activity was accompanied by alteration in isozyme pattern (Bates

and Chant, 2008).

Ashfaq et al. (2010) investigated Urdbean leaf crinkle virus (ULCV) causing systemic

infection in blackgram (Vigna mungo (L.) Hepper) in two genotypes, Mash-88 susceptible and

CM-2002 resistant at different growth stages under both the inoculated and uninoculated

conditions. In Mash –88 the activities of PO increased non-significantly at all growth stages and

in resistant genotype PO activities increased after 15 and 30 days of inoculation respectively.

The antioxidant status as well as protein composition of faba bean leaves infected with Bean

yellow mosaic virus (BYMV) and BYMV-infected leaves revealed POD, CAT, and SOD

induced activities Mohammed et al. (2010).

Srivastava et al. (2012) studied bean common mosaic virus influenced the peroxidase

activity in healthy and diseased hyacinth bean leaves at different intervals of time. The infected

leaves showed greater intensities of the peroxidase bands in comparison with extracts of the

healthy leaf (Shilpashree et al. 2013). PEMV induces the accumulation of ABA, SA and Hsp70

and enhances peroxidase (POX) activity at 15 dpi, when it is already transmitted throughout the

pea plant (Kyseláková et al. 2013).

Primary Productivity:

The production of full grown seeds depends to a greater extent on the availability of

assimilates for accumulation in them, which in turn is determined by the magnitude of

differences between the gross photosynthesis and respiration in leaves. Various processes

upsetting this balance would cause an adverse effect on the productivity of crops, virus infection

being one of them. The virus infection causes gross loss in quality and quantity of the crop and

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this information is essential to make a proper assessment of the economics of the disease control.

Primary productivity of pea leaves influenced by arhar mosaic virus infection has been studied

by Singh and Srivastava (1979).

Rao (1986) found productivity losses in pea infected by cucumo virus. Suresh et al.

(1988) reported increase in respiration rate of Phaseolus vulgaris leaves infected with bean

common mosaic virus. Singh et al. (1989) studied the effect of southern bean mosaic virus

infection on the photosynthetic rate and primary productivity of cowpea. They reported that the

virus infection reduced both the net and gross production of dry matter and increased the

respiratory loss. The respiration losses of assimilate increased with plant age continuously in

virus-infected tissues but gross and net production increased up to 60 days and then decreased.

Ghoshal (1995) reported that the net and gross production was reduced however the

respiration rate became higher in CMV infected leaves of broad bean than their healthy

counterparts.

Srivastava (2005) reported the effect of ULCV infection on primary productivity. ULCV

infection adversely affected the primary productivity of Urd bean. Rate of net production and

gross production decreased and that of respiratory loss increased in ULCV infected Urd bean

leaves. Similar observation studied on hyacinth bean infected by BCMV (Srivastava et al. 2012).

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