Australian Journal of Basic and Applied Sciences, 2(2): 323-330, 2008 ISSN 1991-8178

Biochemical Influence of Cyanophos Insecticide on Radish Plant I. Changes in Some Enzymatic Activities Exposed to Various Concentrations During the Growth Period

Faten A. El-Daly and Mary S. Khalil

Department of Botany, Faculty of Science, Cairo University, Egypt.

Abstract: A field experiment was conducted to investigate the effect of post spraying the insecticide “cyanophos”, 0-(4-cyanophenyl) 0,0-dimethyl phosphorothioate” with different concentrations (0.0, 0.025, 0.037 and 0.05% v/v) on some enzymatic activities of radish plant at three different intervals through the test period. The enzymes are glutamic pyruvic transaminase (GPT), glutamic oxaloacetic acid transaminase (GOT), alkaline phosphatase, acid phosphatase and nitrate reductase. The results revealed different responses of the different enzymes depending on the concentration, the frequency and the time of spraying. The obtained data demonstrated that after 3 days of spraying. GPT and GOT decreased after 1st spray with the tested concentrations, this investigation was converted after 3rd spray and the effect was decreased after 12 days. The effect of insecticide on alkaline phosphatase was insignificant after 1st spray but the enzyme activity was enhanced after 2nd and 3 rd spraying. It was found that after 12 days of the second spray, the enzyme activity enhanced mostly by 0.037 and 0.05% concentrations. Regarding the acid phosphatase, the activity was enhanced by application of the moderate concentration (0.037%) after each spray. After 12 days the treated plants showed insignificant effect of the acid phosphatase. For the nitrate reductase, the results showed that the cyanophos has insignificant effect on its activity regardless of the intervals except after 3rd spray after 12 days whereas the enzyme activity increased gradually with the tested concentrations.

Key words: Organophosphorus insecticides, radish plant, trnsaminases, phosphatases, reductase enzymes

INTRODUCTION

Insecticides are used extensively to control plant insect. Heavy use of pesticides on field crops has begun to receive much attention. Numerous restrictions have been imposed by various regulatory bodies to ensure safe use of pesticides and to protect consumers from adverse side effects. Certain risks of pesticide toxicity are still unknown, as the interactive effects of multiple pesticides application on plant. The toxicity and harmful effect of insecticides depend on edaphic conditions and/or test plant species. Many researches have studied how to remove pesticides from food products (Zidan et al., 1991; Lee et al., 1991). Organophosphorus compounds used in agriculture, usually alter the chemical composition and nutritive value of plant product. Deep investigations should be encountered for solving the problem of hygienic regulation of the conditions for their use in agriculture. The half life time (t½ ) rate of the organophosphorus insecticides was fast ranging between 0.97 and 3.84 days (Cabras and Angioni, 2000). Cyanophos 0-(4-cyanophenyl) 0,0 dimethyl phosphorothioate is an organophosphorus insecticide. It is widely used to control various aplididaes, coccidaes in cotton, fruits and vegetables, it is recommended for use at 25-50 g active ingredients/hl. Radish was chosen as one of the popular, cheapest and important plant whether its root or its leaves, as it contains certain metals and different stored food reserves. Thus their metabolic changes during the germination were thought to present some information concerning the mode of action of the insecticide under study in insect control. The aim of this work is to study the effect of repeated applications by different concentrations of cyanophos on some enzyme activities of radish plant

MATERIALS AND METHODS

Radish seeds (Raphanus sativus L.) were kindly supplied by the Agricultural Research Center, Giza, Egypt. A homogenous batch of seeds was selected for uniformity of size, shape and viability were sown in the experimental field station of the Faculty of Agriculture, Cairo University, following the usual procedure of

Corresponding Author: Faten A. El-Daly, Department of Botany, Faculty of Science, Cairo University, Egypt.

323 Aust. J. Basic & Appl. Sci., 2(2): 323-330, 2008

Fig. 1: Changes in the activity of GPT of radish plant, Raphanus sativus, after 3 (A) and 12 (B) days of treatment with different concentrations of insecticide during the growth period. irrigation. Twelve days after sowing, the growing plants were sprayed with 45 ml/plant of cyanophos insecticide solution containing 0.0%, 0.025%, 0.037% and 0.05%. Spraying with cyanophos was repeated at 24 and 36 days of plant age. After 3 and 12 days of each spraying, certain plants from each treatment were randomly picked up and used for enzymatic activities. In this investigation, fresh leaves were used for estimation of GPT, GOT, alkaline and acid phosphatases and nitrate reductase. The methods of Bergmeyer (1974) were adopted to determine transaminases as ìmol pyruvate/min/mg fresh weight. The determination of alkaline and acid phosphatases as King Armstrong units/mg fresh weight.

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Fig. 2: Changes in the activity of GOT of radish plant, Raphanus sativus, after 3 (A) and 12 (B) days of treatment with different concentrations of insecticide during the growth period.

The reduction of nitrate to nitrite was adopted by the method of Aparicio and Maldonado (1978) and determined as ìmol nitrite/mg fresh weight. Statistically, the data were analyzed on the basis of multifactor analysis (SPSS ver. 16) to clear the effect of time, concentration of insecticide, and the spraying, as well as their interaction on enzymes activities of radish plant during the growth season.

RESULTS AND DISCUSSION

Since our knowledge about the effect of cyanophos on the biochemical studies in plants is quite meager, it is of interest to investigate the effect of this insecticide on transaminases, (GPT and GOT), alkaline and acid phosphatases and nitrate reductase.

325 Aust. J. Basic & Appl. Sci., 2(2): 323-330, 2008

Transaminases: These enzymes have been used in the transamination reactions including nearly all the L-aminoacids and also used in the metabolic roles of transamination. As shown in Fig. (1A), it is evident that after 3 days from 1st treatment there was a highly significant decrease P<0.001 of GPT activity by all concentrations comparing with the untreated plant. This observation was converted by 2nd and 3 rd treatments whereas the GPT activity is enhanced more than control, most prominently by 0.05% concentration. The obtained results in Fig. (1B) indicated that the activity of GPT was obviously enhanced by all the concentrations of cyanophos after 12 days of the second spraying. The third spraying insignificantly (P>0.05) suppressed its activity. In this regard, Kore and Patil (1995) studied the effect of foliar application of two herbicides on the activity of respiratory peroxidase in Parthenium hysterophorus, the activity of the enzyme was suppressed after 72 hours. After 3 days of 1st treatment the all concentrations of cyanophos significantly decreased (P<0.05) as shown in Fig. (2A) the activity of GOT compared to the control. Regarding of second and third spray, the different concentrations of the insecticide enhanced the GOT activity.

Fig. 3: Changes in the activity of alkaline phosphatase of radish plant, Raphanus sativus, after 3 (A) and 12 (B) days of treatment with different concentrations of insecticide during the growth period.

326 Aust. J. Basic & Appl. Sci., 2(2): 323-330, 2008

Fig. 4: Changes in the activity of acid phosphatase of radish plant, Raphanus sativus, after 3 (A) and 12 (B) days of treatment with different concentrations of insecticide during the growth period.

After 12 days, GOT activity was markedly enhanced after 1st and 2 nd spraying at 0.037% concentration as shown in Fig. (2B), whereas this increment was converted after 3rd spray. In this connection Abd El_Mageed (1998) showed the effect of cyanophos on peroxidase activity, a significant decrease in the specific enzyme activity. Wheelock et al. (2005) showed that some organophosphorus pesticides can cause adverse physiological effects on carboxylesterases. Tripathi (2005) reported that organophosphate and some other pesticides inhibit the activities of metabolic enzymes involved in aerobic and anaerobic metabolism and decrease the concentration of macromolecules in cells. Pesticide might be interfering at some step(s) in information processing to inhibit enzyme activity and the reversal in activity may be due to de novo synthesis of enzymes. Pesticides also cause various cellular and subcellular abnormalities Tripathi (2005).

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Fig. 5: Changes in the activity of nitrate reductase of radish plant, Raphanus sativus, after 3 (A) and 12 (B) days of treatment with different concentrations of insecticide during the growth period.

Alkaline and Acid Phosphatases: Phosphatases are enzymes, which catalyze the liberation of orthophosphate from complex organic phosphorus compounds and an organic moiety and are thus believed to have an essential function in the nutrient dynamics of most of the ecological niches. These enzymes maintain phosphorus balance in the plant field (Meenakshi, 2007). It is known that acid phosphatase (APase) plays an important role in the detoxification process of toxic compounds entering the body (Zheng et al., 2007). It could be noticed from the results Fig. (3A) that alkaline

328 Aust. J. Basic & Appl. Sci., 2(2): 323-330, 2008 phosphatase activity responded differently to all concentrations of cyanophos, at which significantly enhanced activity appeared during the test period. Similar results were noticed in the acid phosphatase activity except at 0.05% concentration after third spraying Fig. (4A). This observation is supported by the study of El-Gendy et al. (1990). Twelve days after spraying it was found that the different concentrations of insecticide has a remarkable effect on alkaline phosphatase activity than on acid phosphatase Figs. (3B and 4B). After the third spraying in all treated plants the alkaline phosphatase activity has been reduced by all concentrations whether low or high. The results in this investigation showed that elevating the phosphorus levels increased the phosphatase activity. Shahin et al. (2005) reported that chronic exposure (multiple-dose, greater than or equal to 6 months duration to oragnophosphorus pesticides was associated with increase activities of catalase, SOD and glutathione peroxidase in erythrocytes. The increase of alkaline or acid phosphatase is owing to increase the permeability of plasma membrane which may be due to stress condition of the treated plant with organophosphorus compounds (Lopez et al., 2007).

Nitrate Reductase: Nitrate reduction is the first step in nitrogen assimilation. It is catalyzed by nitrate reductase. In the current work, the results of nitrate reducatse recorded in Fig. (5A) showed the increase at 0.025% of the nitrate reductase activity compared to the control after first spraying, while there was no change after second and third spraying. This later case remained after 12 days of first and second spraying (Fig. 5B). The data showed that after 3rd spraying the nitrate reductase activity was enhanced in the treated plant than control. These results are in concomitant with those obtained by Lopez et al. (2007), who reported that different pesticides including organophosphates have been reported to induce oxidative stress due to generation of free radicals and alteration in antioxidant defense mechanism. All the pesticides proved deleterious and suppressed the catalytic activity of all the enzymes considerably depend on the concentration Bhardwaj and Shekhar (2005). Singh and Shaner (1995) reported that enzymes in different amino acids biosynthetase pathways identified as a target of several pesticides. Statistically, there was interaction between the frequency of spraying, time and concentrations of the insecticide (P<0.001) on GPT, alkaline phosphatase and nitrate reductase. P>0.05 on GOT. P<0.05 on acid phosphatase. The most significant conclusion which can be derived from this work is that the use of this pesticide be restricted to non-edible crops or that ways to reduce its residue levels in plant tissues, such as using it with astringent safety interval and low concentration.

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