Biochem. Physiol. Pflanzen 179, 799-801 (1984)

Short Communication

Activities of Acid and Alkaline Phosphatases in Relation to Sex Differentiation in Carica papaya L.

V. S. JAISWAL, PRATAP NARAYAN and MADAN LAL Department of Botany, Banaras Hindu University, Varanasi, India

Key Term Index: phosphatase, sex expression; Carica papaya

Summary

Changes in the activities of acid and alkaline phosphatases were analysed in vegetative and reproductive tissues of male and female plants of Carica papaya L. The reproductive tissues of male plants showed greater activities of acid and alkaline phosphatases than those of female plants, whereas activity of each enzyme was more or less similar in vegetative apical meristems of both the sexes.

Sex expression in flowering plants has been found to be affected by several plant growth regulators (MOHAN RAM and JAISWAL 1970, 1974; FRANKEL and GALUN 1977; MOHAN RAM 1980; JAISWAL and KUMAR 1980a). Relationship between endogenous levels of plant hormones and sex expression has also been investigated (GALUN et al. 1965; VINCE-PRUE 1975; FRANKEL and GALUN 1977; CHAMPAULT et al. 1981). The diffe­rences in the endogenous levels of plant hormones are probably connected with enzyme activities. A few workers have tried to investigate the correlationship between enzyme activities and sex expression (RETIG and RUDICH 1972; JAISWAL and KUMAR 1980b, 1981, 1983).

The present findings describe the possible involvement of acid and alkaline phospha­tases in sex expression of C. papaya, a dioecious plant.

Plants of C. papaya L. were raised from seeds in field with properly manured soil. Vegetatively growing apical meristems, floral primordia and mature flowers were harvested from known male and female plants for the analyses. Explants were rinsed 3-4 times with tap water and twice with distilled water, dried on blotting paper and weighed. One gram of each tissue was homogenized with chilled pestle and mortar in 6 ml of O.IM Tris-HCI buffer (pH 7.5) containing 5 mM 2-mercaptoethanol (YA­MAYA and MATSUMOTO 1981). The macerates were centrifuged at 12,000 rev min-1 for 30 min at o °C. The clear supernatants were used as enzyme extracts.

Add phosphatase activity was assayed in a medium containing 0.2 ml of enzyme extract, 0.8 ml of 5 mM disodium p-NPP in 0.1 1\1 citrate buffer (pH 4.8) and 1.0 ml of the same buffer. Citrate buffer was replaced with 0.11\1 Tris- HCI buffer (pH 9.0) in case of alkaline phosphatase assay. The reaction mixture was incubated at 30°C and after 30 min the reaction was stopped by adding 3 ml of 0.1 N NaOH. The amount of released p-NP was measured at 410 nm using spectro-colorimeter. Incubations terminated at 0 time were used as blank tests. The activity of each enzyme was expressed in terms of

Abbrcviat£ons: p-NPP = p-nitrophenyl phosphate; p-NP = p-nitrophenol; GA = gibberellin

800 V. S. JAISWAL et al.

Table 1. Acid and alkaline phosphatase activities in crude extracts of vegetative and reproductive tissues of male and female plants of Carica papaya.

Data are expressed mean value ± S.D.

Sex type

Male

Female

Developmental stage

Vegetative apical meristem Flower primordia Mature flowers

Vegetative apical meristem Flower primordia Mature flowers

Acid phosphatase activity (Units g-l fro wt.)

63.0 ± 2.6 63.4 ± 2.4 65.0 ± 2.8

62.0 ± 2.2 36.4 ± 1.6 34.6 ± 1.5

Alkaline phosphatase activity (Units g-l fro wt.)

12.5 ± 0.9 13.0 ± 1.1 13.5 ± 1.2

12.2 ± 0.9 2.5 ± 0.4 2.5 ± 0.3

units g-l fresh weight and 1 unit was defined as,ug of p-NP released min-1 at 30 °0. Each experiment was repeated at least thrice.

Changes occuring in the activities of acid and alkaline phosphatases of different tissues of male and female plants of C. papaya are shown in Table 1. Vegetatively growing apical meristems of both male and female plants did not show any significant difference in the levels of phosphatase activities for each enzyme. Phosphatase activities increased a little in flower primordia and mature flowers of male plants during anthesis. A signi­ficant decrease in the activities of acid as well as alkaline phosphatase was observed in female reproductive tissues at bo~h the stages of development. Level of acid phosphatase activity in female reproductive tissue was about 0.5 times lower than the level recorded in male reproductive tissue. Whereas, level of alkaline phosphatase activity was recorded to be about 5 times lower in reproductive tissues of female plants than the level recorded in the reproductive tissues of male plants at both the stages of flower development.

In many plants, higher levels of endogenous gibberellins (GA) have been detected in male individuals/reproductive tissues and a correlationship between higher GA con­tent and male sex expression has been established (VINCE-PRUE 1975; FRANKEL and GALUN 1977). GA is found to induce maleness in C. papaya (KUMAR 1982). GA is also known to induce the enhancement of acid phosphatase activity in several plant tissues and its release therefrom (JONES 1969; AKIYAMA and SUZUKI 1980,1981) and it is likely that higher activities of phosphatase enzymes in reproductive tissues of male plants are, probably, due to induction by higher GA contents in those tissues. Therefore, it is conjectured that an increase in phosphatase activity induces or supports the develop­ment of male sex organs whereas a decrease in the activities promotes the formation of female sex organs in C. papaya.

Acknowledgements

Authors are grateful to the O.S.I.R., New Delhi for financial assistance and thankful to the Head of the Department of Botany, B.H. U. for providing laboratory facilities.

Phosphatase Activity and Sex Differentiation in Carica papaya

Referenees

AKIYAMA, '1'., and SUZUlCI, H.: Biochem. Physiol. Pflanzen 175,436-446 (1980). AKIYAMA, '1'., and SUZUKI, H.: PI. Sci. Lett. 21, 137-143 (1981).

801

CHAMPAULT, A., CHUNG, S., GUERIN, B., KAHLEM, G., LHERMITTE, A., TELLER, G., and DURAND, B.: In: Metabolism and Molecular Activities of Cytokinins (eds.) GUERN, J., and PEAUD-LENOEL, C., Springer-Verlag, Berlin, Heidelberg, New York 1981, pp. 129-139.

FRANKEL, R., and GAL UN, E.: Pollination Mechanism, Reprodnction and Plant Breeding, Springer-Verlag, Berlin, Heidelberg, New York 1977, p. 281.

GALVN, E., IzHAE, S., and ATSMON, D.: PI. Physiol. 40, 321-326 (1965). JAISWAL, V. S., and KUMAR, A.: J. Exp. Bot. 31, 497-500 (1980a). JAISWAL, V. S., and KUMAR, A.: Biochem. Physiol. Pflanzen 175, 578-581 (1980b). JAISWAL, V. S., and KUMAR, A.: Z. Pflanzenphysiol. 102, 299-302 (1981). JAISWAL, V. S., and KUMAR, A.: Curr. Sci. 52, 368-369 (1983). JONES, K. C.: PI. Physiol. 44,1695-1700 (1969). KUMAR, A.: Ph. D. Thesis, Banaras Hindu University, Varanasi, (India) 1982. MOHAN RAM, H. Y.: PI. Biochem. J. (S. M. Sircar memorial volume) pp. 78-88 (1980). MOHAN RAM, H. Y., and JAISWAL, V. S.: Experientia 26,214-216 (1970). MOHAN RAM, H. Y., and JAISWAL, V. S.: In: Plant Growth Substances (ed.) SU~lIKI, Y. Hirokawa

Publ. Co., Inc. Tokyo (1974). RETIG, N., and RUDICH, J.: Physiol. PI. 27, 156-160 (1972). VINCE-PRUE, D.: Photoperiodism in Plants, McGraw Hill Book company Limited (U.K.), Maiden­

head, Berkshire, England, pp. 312-330. YAMAYA, '1'., and MATSUMOTO, H.: PI. & Cell Physiolo 22, 1355-1365 (1981).

Received June 20, 1984; accepted July 1, 1984

Author's address: Dr. V. S. JAISWAL, Reader in Botany, Banaras Hindu University, Varanasi -221 005, India.