Changes In Biochemical Parameters In Healthy And Root-Knot Nematode Infested Varieties Of Ridge Gourd
SHOBHA1*, G. and KANTHARAJU2, V.
1Department of Plant Pathology, University of Agricultural Sciences, Raichur-584104, Karnataka
2KRC, College of Horticulture, Arabhavi, Belagum, Karnataka
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ABSTRACT
Ridge gourd (Luffa acutangula roxb.) is important Cucurbitaceous vegetable and susceptible host crop facing considerable yield loss due to pest and diseases. The biochemical analysis was carried out in resistant, moderately resistant, susceptible and highly susceptible varieties of both healthy and root-knot nematode infested roots to know the accumulation and variations in biochemical constituents with regard to total phenols, total amino acids, reducing sugar and total sugar. The infested roots of variety Arka Sumeet (830 mg/g, 0.097mg/g) recorded significantly higher amount of total phenol and amino acids compared to healthy roots and all other varieties studied. Whereas, reducing sugar content was more in infested roots of variety Ridge gourd PN (15.00 mg/g) when compared to healthy roots (10.00 mg/g). Wherein, non-reducing sugar content was maximum in healthy roots of variety Ridge gourd PN (12 mg/g) compared to that of infested roots (9.00 mg/g) of same variety. Whereas healthy roots of Ridge gourd PN (9.50 mg/g) recorded more of non reducing sugar compared to (6.75 mg/g) in infested roots of same variety.
KEY WORDS: Amino acids, Phenols, Ridge gourd, Root-knot nematode, Sugars and amino-acids
INTRODUCTION
Ridge gourd (Luffa acutangula roxb.) is more popular vegetable in the south and east India. It is known by different names in different regions as Torai, Mongitorai, Araturai, Dorkavidarbha, Turi, Hirekayi, Beera, Peerkankai, Peecha kam, Cherupee rum and Ribbed
Changes in biochemical parameters in healthy and root-knot nematode infested varieties of ridge gourd
leefa. Among the production constraints, plant parasitic nematodes are one of the major limiting factors to production. The root-knot nematodes (Meloidogyne spp.) are cosmopolitan pathogens of plants and cause over $100 billion in annual crop losses worldwide (Bird et al., 2009). The host range of Root-knot nematode is extensive with more than two thousands of plant species (Sasser, 1980; Bird et al., 2009). Four common Meloidogyne species (Meloidogyne incognita, Meloidogyne javanica, Meloidogyne hapla and Meloidogyne arenaria) comprise up to 95% of all root-knot nematode populations. M. incognita is the most common species accounting for 64 per cent of total population and infects almost all cultivated plants, which makes it perhaps the most damaging of pathogens (Sasser et al., 1983; Abad et al., 2007).At present, only limited information is available on variation in biochemical changes taking place in healthy and root-knot nematode infested ridge gourd varieties of resistant, moderately resistant, susceptible and highly susceptible during the nematode attack in a pot experiment. This study helped to understand to know biochemical constituents viz., phenols, sugars and aminoacids involved in resistant, moderately resistant, susceptible and highly susceptible reaction of variety to Meloidogyne incognita.
MATERIALS AND METHODS
The screened ridge gourd varieties were taken for analysis of biochemical constituents’ viz., phenols, sugars and amino acids in resistant (Arka Sumeet), moderately resistant (RNR), susceptible (US-6001) and highly susceptible Ridge gourd PN) seedlings. Seedlings were raised in pots with three kilograms sterilized soil. Three replications were maintained for each variety. After seven days of seedling germination, freshly hatched second stage juveniles (J2) of M. incognita (2 J2/ g soil) were inoculated into four holes made in the soil around the base of each plant near the rhizosphere. Regular watering, manuring and weeding were followed. The plants were carefully depotted 60 days after nematode inoculation and were carefully washed, cleared of soil.
Total amino acids in root were determined by the ninhydrin method described by Spies (1957) using leucine as standard citrate buffer and and ninhydrine solution as reagent. Reducing sugar of the powdered roots was estimated by Simogyi-Nelson method (Nelson, 1944) using reagent A, reagent B (Nelson Chromogenic reagent) and Arsenomolybdate colour reagent. Total sugars estimated by Loomis and Shull (1957) method by using anthrone reagent. Total phenol was estimated in the roots by following the method of Swain and Hills (1959) using Folin Denis reagent (FDR), saturated sodium carbonate solution.
RESULTS AND DISCUSSSION
The study indicated that resistant variety Arka Sumeet (685 mg/g) recorded higher amount of total phenol than moderately resistant variety RNR (660 mg/g), susceptible US-6001 (590 mg/g) and highly susceptible ridge gourd PN (440 mg/g). The infested roots of variety Arka Sumeet (830 mg/g) recorded significantly higher amount of total phenol followed by RNR (798 mg/g), US-6001 (638 mg/g) and ridge gourd PN (460 mg/g) compared to healthy roots (Table 1).
Phenol content and its enhancement during disease progress were least in susceptible varieties. This is in agreement with the findings of Sireesha and Mohanty, 2015; Balasubramanian and Purushothaman, 1972; Ravichandra, 1987; Nagesh et al., 1998 and Gopinath (2001) who had reported phenolic content was higher in galled (infested roots) than in healthy tissue. Sharma and Trivedi, 1996; Mohanta and Mohanty (2012) who reported that, there was an increase in phenolic substances by 36.92 per cent during post infection period compared to healthy check. In both resistant and highly susceptible varieties sequential development of chitinase, Peroxidase and acid phosphatise takes place but level of these compounds was much higher in roots of resistant variety compared to susceptible variety (Mohamed and Hasabo 2005).
Amino acid content more in Arka Sumeet (0.089 mg/g) compared to ridge gourd PN (0.042 mg/g). Further, the amino acid content more in infested roots of Arka Sumeet (0.097 mg/g) compared to healthy roots (0.089 mg/g) and least in ridge gourd PN (0.049 mg/g and 0.042 mg/g) of infected and healthy roots respectively (Table 2). Similar results obtained by Singh et al. (1979), Tayal and Agarwal (1982), Ravichandra (1987), Sharma and Trivedi (1996). Nayak and Mohanty (2010) who opined that, brinjal variety Pusa Purple Long inoculated roots contained higher amino acids than healthy roots. Gautam and Poddar (2014) who had reported maximum quantity of total amino acids in root-knot nematode infested brinjal susceptible variety compared to resistant variety.
In the present investigation, (Table 3) total sugars and reducing sugars contents were more in infested roots of variety ridge gourd PN (24 mg/g and 15 mg/g) than resistant variety Arka Sumeet (12.0 mg/g and 9.50 mg/g) compared to healthy roots. Further, the healthy roots of ridge gourd PN (12.0 mg/g) recorded more non-reducing sugars as against resistant variety Arka Sumet (4.50 mg/g) compared to infested roots.
Similar results obtained by several workers viz., Nayak and Mohanty (2010) and Mohanta and Mohanty (2012) who opined that 41.21 per cent increase in total sugar contents in the inoculated roots of okra variety LBH-55 compared to healthy roots. Senthilkumar et al., (2007) who found the increased amount of total and reducing sugar content in M. graminicola infested susceptible varieties compared to resistant varieties. The infestation of plant parasitic nematode caused increase in sugar content and it was also observed that increased sugars helpful for the survival of nematodes. The increase in sugar in infected plants may be alteration in host metabolism due nematodes, so that the respiratory substrates move towards the site of infection from the other parts of plant in order that more carbohydrates are available for respiration and release of energy.
The increase in phenolics in resistant plants is due to high activity of a-glucosidase, which converts non-toxic phenolic glycosides to toxic phenolics which are inhibitory to the pathogen. The increase in Amino acid concentration in infected plants may be either due to the synthesis of new enzyme proteins or the contributions from nematodes (Nayak and Mohanty, 2010). The complex plant nematode interaction may cause the hydrolysis of sucrose and the utilization of simple sugar by the nematode and may be the reason for higher sugar level in infected tissues (Ganguly and Dasgupta, 1983).
In conclusion, the present investigation indicated that M. incognita played key role in altering the normal biochemical processes of the ridge gourd. Further, opinion that the basic information provided in this investigation will certainly helpful to understand the complicated areas of the biochemical mechanisms of plant nematode-interaction in ridge gourd relating to root-knot and other plant parasitic nematodes.
ACKNOWEDGEMENT
The authors are thankful to the Department of Plant Pathology, college of agriculture, University of agricultural Sciences Raichur for extending infrastructural facilities for undertaking the study.
Table 1.Effect of root-knot nematode, M. incognita on phenol content (mg/g) in varieties of ridge gourd roots with varied degrees of resistance
Sl. No. / Variety / Reaction / Phenol content (mg/g)Healthy / Infested
1 / Arka sumeet / R / 685 / 830
2 / RNR / MR / 660 / 798
3 / US-6001 / S / 590 / 638
4 / Ridge gourd PN / HS / 440 / 460
Table 2. Quantitative estimation of amino acid (mg/g) fresh weight of ridge gourd root infested by root-knot nematode
Sl. No. / Variety / Reaction / Amino acid content (mg/g)Healthy / Infested
1 / Arka sumeet / R / 0.089 / 0.097
2 / RNR / MR / 0.050 / 0.057
3 / US-6001 / S / 0.040 / 0.048
4 / Ridge gourd PN / HS / 0.042 / 0.049
Table 3. Effect of root-knot nematode, M. incognita on Sugars (mg/g) in cultivars of
ridge gourd roots with varied degrees of resistance
Sl. No. / Variety / Reaction / Total sugars content (mg/g) / Reducing sugars (mg/g) / Non reducing sugars (mg/g)Healthy / Infested / Healthy / Infested / Healthy / Infested
1 / Arka Sumeet / R / 11.50 / 12.00 / 7.00 / 9.50 / 4.50 / 2.50
2 / RNR / MR / 15.25 / 16.75 / 7.25 / 10.25 / 8.00 / 6.50
3 / US-6001 / S / 18.00 / 21.0 / 8.50 / 14.25 / 9.50 / 6.75
4 / Ridge gourd PN / HS / 22.00 / 24.0 / 10.00 / 15.00 / 12.00 / 9.00
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