Short communication
Catecholase and cresolase activities and phenolic
content in mango (
Mangifera indica
L.)
at panicle initiation
R.R. Sharma
a,*, A.M. Goswami
a, C.N. Singh
b,
O.P. Chhonkar
b, Gyanendra Singh
ba
Division of Fruits and Horticultural Technology, Indian Agricultural Research Institute, New Delhi 110012, India
b
Department of Horticulture, CCS College, Muzaffar Nagar, Uttar Pradesh, India
Accepted 26 April 2000
Abstract
Catecholase and cresolase (PPO) enzyme activities and phenolic content were measured in different mango cultivars at panicle initiation. Enzyme activity and phenolic content varied widely amongst eight cultivars, the maximum being in Bhadauran and minimum in Tommy Atkins. Floral malformation incidence was maximum (53.75%) in `Tommy Atkins' and minimum in `Bhadauran' (1.10%). A strong negative correlation was found between both the enzyme activity, phenolic content at panicle initiation and the incidence of ¯oral malformation. Thus, PPO activity and level of phenolic compounds at panicle initiation may give a possible estimate of malformation incidence in mango.#2001 Elsevier Science B.V. All rights reserved.
Keywords: Catecholase; Cresolase; Floral malformation;Mangifera indica; Polyphenol oxidase; Phosphate buffer; Substrate
1. Introduction
Catecholase and cresolase oxidase are the two widely distributed forms of polyphenol oxidase enzyme in the plant kingdom. Being easily detectable, these enzymes have been studied thoroughly for assessing their role in higher plants.
*
Corresponding author. Tel.:91-115-785214; fax:91-115-766420.
E-mail address: rrs_fht@iari.ernet.in (R.R. Sharma).
Mayer and Harel (1979) and Vaughan and Duke (1984) reported that polyphenol oxidase is responsible for in vivo synthesis and accumulation of phenolic compounds in plants, which are considered to impart resistance against diseases. Further, it is well known that ¯oral malformation is the most dreaded disorder of mango, rendering mango orcharding unproductive in north Indian conditions and in other regions of the world (Pandey et al., 1977; Hifny et al., 1978; Ram, 1991). The conditions, both exogenous and endogenous, prevailing at the time of panicle emergence may decide, which of the panicles is going to be malformed (Dashhan, 1987; Ram and Yadav, 1999).
However, the investigations on catecholase and cresolase enzyme activity and phenolic content at panicle initiation in relation to malformation are lacking in mango. These studies were, therefore, conducted in different mango cultivars at panicle emergence, which will help in assessing the possible role of polyphenols, catecholase and cresolase enzymes in mango malformation.
2. Materials and methods
Mango cultivars viz. Eldon, Sensation, Tommy Atkins, Langra, Chausa, Dashehari, Amrapali, Mallika and Bhadauran were selected for these studies. Fully swollen ¯oral buds at panicle emergence, were used for measuring enzyme activity and phenolic contents. Healthy and malformed panicles in each variety were counted and averaged for calculating malformation incidence. Correlations between enzyme activities and percent malformed panicles were calculated.
2.1. Estimation of phenolic content
Phenolic contents were measured using the Folin Ciocalteu reagent method suggested by Slinkard and Singleton (1977) with slight modi®cations (Sharma et al., 1994) and are represented as mg gÿ1
of fresh tissue weight.
2.2. Preparation of enzyme extract
fractionation was carried out and the fraction precipitating between 45 and 95% saturation was collected and re-dissolved. This solution, after dialysis was used as an enzyme source.
2.3. Enzyme assay
Both catecholase and cresolase activities were measured spectrophotometri-cally at 400 nm as per the procedure described by Sanchez-Ferrer et al. (1988) with slight modi®cations. Catecholase activity was measured using 30 mM 4-methyl catechol (4MC), as substrate, made in 10 mM sodium accetate buffer pH 4.5. To 1 ml crude enzyme extract, 3 ml of 100 mM phosphate buffer pH 7.3 was added. To this mixture, 1 ml substrate was added at zero time. The change in absorbance at 400 nm was recorded in a CL-1200 spectrophotometer. The cresolase activity was also measured similarly except that 4-methyl phenol (p -cresol), was used as substrate, made in 10 mM phosphate buffer at pH 7.0. The enzyme activity was represented as change in absorbance at 400 nm/g of tissue weight/min (DA400g
ÿ1
minÿ1
).
3. Results
Catecholase activity varied widely amongst different genotypes. `Bhadauran' exihibited the highest (1.835) and `Tommy Atkins', the lowest catecholase activity (0.823). Similarly, the cresolase activity was highest in `Bhadauran' (1.233) and lowest in `Tommy Atkins' (0.401). A similar pattern was also observed in phenolic content (Table 1). Statistically, PPO activity and phenolic
Table 1
Polyphenol oxidase activity, phenolic content and malformation incidence in different mango cultivars at panicle initiation (®gures in parentheses are transformed values)
Cultivar Polyphenol oxidase activity
Sensation 0.992 0.551 15.20 37.88 (38.00)
Eldon 0.945 0.512 13.21 41.93 (40.34)
Tommy Atkins 0.823 0.401 08.52 53.75 (47.18) Dashehari 1.112 0.752 18.33 31.15 (33.96)
Chausa 0.853 0.429 09.32 52.83 (46.61)
Amrapali 0.937 0.515 12.13 43.77 (41.50) Mallika 0.991 0.544 14.81 38.72 (38.47) Bhadauran 1.835 1.233 22.65 01.10 (6.03)
content between `Tommy Atkins' and `Chausa'; `Eldon' and `Amrapali', and `Sensation' and `Mallika' were not signi®cantly different (P<0.05). Further, the trend of cresolase activity was similar to catecholase activity, though, it was much lower than catecholase. The reaction of these varieties against malformation under ®eld conditions also varied widely (Table 1). `Bhadauran' had least (1.10%) and `Tommy Atkins', the maximum (53.75%) malformation incidence. Other cultivars were intermediate in nature for malformation incidence.
Strong negative correlations between catecholase activity and malformation incidence (rÿ0.923), cresolase activity and malformation (rÿ0.871), and
phenolic content and malformation incidence (rÿ0.812) were observed.
4. Discussion
There exists wide variation in respect to catecholase and cresolase activity and phenolic contents at panicle initiation between the different cultivars tried in this investigation (Table 1). This variation in enzyme activity and phenolic content in different cultivars may be attributed to genetic differences between them (Sharma et al., 1994). All cultivars exhibited higher catecholase activity compared to cresolase activity. Lower cresolase activity may probably be due to its lag period, greater instability and rapid loss during extraction as reported in grape by Wisseman and Lee (1980); Nakamura et al. (1983) and Sharma et al. (1994).
However, it is evident from the results that the levels of catecholase and cresolase activity and phenolic compounds at panicle initiation have direct relation to the occurrence of malformation, which in turn is in¯uenced by different cultivars in mango.
References
Dashhan, D.I., 1987. Physiological studies on malformation of mango panicles. Ann. Agric. Sci. 32, 565±575.
Hifny, H.A.A., El-barkouki, M., El-banna, G.S., 1978. Morphological and physical aspects of the ¯oral malformation in mangoes. Egypt. J. Hort. 5, 43±52.
Mayer, A.M., Harel, E., 1979. Polyphenol oxidase in higher plants: a review. Phytochemistry 18, 193±215.
Nakamura, K., Amano, Y., Kagami, M., 1983. Puri®cation and some properties of a polyphenol oxidase from Koshu grapes. Am. J. Enol. Vitic. 34, 122±127.
Pandey, R.M., Rao, M.M., Pathak, R.K., 1977. Biochemical changes associated with ¯oral malformation. Scientia Hortic. 11, 37±44.
Ram, S., 1991. Horticultural aspects of mango malformation. Acta Hortic. 291, 235±252. Ram, S., Yadav, V.K., 1999. Mango malformation Ð a review. J. Appl. Hort. 1 (1), 70±78. Sanchez-Ferrer, A., Bru, R., Cabanes, J., Garcia-Carmona, F., 1988. Characterization of catecholase
Slinkard, K., Singleton, V.L., 1977. Total phenol analysis: automation and comparison with manual methods. Am. J. Enol. Vitic. 28, 49±55.
Sharma, R.R., Sharma, H.C., Goswami, A.M., 1994. Polyphenol oxidase activity and phenolic content pattern during shoot development of grape (Vitis vinifera L.) in different growing seasons. J. Plant Biochem. Biotechnol. 3 (2), 145±147.
Valero, E., Sanchez-Ferrer, A., Varon, V., Garcia-Carmona, F., 1989. Evolution of grape polyphenol oxidase activity and phenolic content pattern during maturation and vini®cation. Vitis 28, 85±95. Vaughan, K.C., Duke, S.O., 1984. Function of polyphenol oxidase in higher plants. Physiol. Plant
60, 106±112.
