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Effect of malformation on changes in endogenous gibberellins and cytokinins during floral development of mango
Scientia Horticulturae, 28 (1986) 235--241 Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands
235
EFFECT OF MALFORMATION ON CHANGES IN ENDOGENOUS GIBBERELLINS AND CYTOKININS DURING FLORAL DEVELOPMENT OF MANGO
L.D. BIST and SANT RAM Department o f Horticulture, College of Agriculture, G.B. Pant University of Agriculture and Technology, Pantnagar, Nainital, U.P. (India) Experiment Station Research Paper No. 3632 (Accepted for publication 4 June 1985)
ABSTRACT
Bist, L.D. and Ram, S., 1986. Effect of malformation on changes in endogenous gibberellins and cytokinins during floral development of mango. Scientia Hortic., 28: 235--241. Patterns of gibberellin content of developing malformed mango inflorescences were very different from those in normal inflorescences. Cytokinin changes in healthy and malformed tissues followed a similar pattern, but cytokinin concentrations were always higher in the malformed inflorescences. Some qualitative differences were detected between chromatographs of cytokinins from malformed and healthy inflorescences. Keywords: auxin ; cytokinin ; floral malformation; gibberellin ; inhibitor ; mango. Abbreviation: LSD = least significant difference.
INTRODUCTION M a l f o r m e d panicles o f m a n g o have short, t h i c k m a i n a n d p r i m a r y rachises w i t h excessive b r a n c h i n g , giving t h e panicle a c h a r a c t e r i s t i c c l u s t e r e d a p p e a r ance. T h e flowers o f m a l f o r m e d panicles are usually m a l e , sterile and bigger t h a n t h o s e f r o m h e a l t h y panicles, w i t h v e r y low p e r c e n t a g e o f h e r m a p h r o dite flowers. S u c h panicles v e r y s e l d o m set fruits. M o s t o f t h e m d r y up during t h e s u m m e r a n d h a n g as b l a c k e n e d b u n c h e s , b u t a f e w c o n t i n u e to g r o w until t h e n e x t season (Singh, 1 9 7 8 ; S h a w k y et al., 1980). This t y p e o f d i s o r d e r is a m a j o r p r o b l e m , causing h e a v y losses t o m a n g o g r o w e r s ( A t t i a h , 1 9 5 5 ; Mallik, 1 9 6 3 ; Prasad et al., 1 9 6 5 ; S c h w a r t z , 1 9 6 8 ; F l e c h t m a n n et al., 1 9 7 0 ; Malo a n d McMillan, 1 9 7 3 ; A n o n . , 1983). Studies c o n d u c t e d so far have n o t clearly revealed t h e cause or c o n t r o l o f floral m a l f o r m a t i o n o f m a n g o ( C h a d h a et al., 1979). P a n d e y et al. {1974)
0304-4238186/$03.50
© 1986 Elsevier Science Publishers B.V.
236 reported low auxin and high inhibitor activity in malformed mango panicles. The endogenous levels o f gibberellins in malformed tissues have been reported as both high (Abou-Hussein et al., 1975; Mishra and Dhillon, 1979} and low (E1-Ghandour et al., 1976). Recently, malformin-like substances have been reported in the malformed mango panicles (Ram and Bist, 1984}. No work has been done on endogenous levels of cytokinins of malformed panicles. Investigations were therefore undertaken into the effect of malformation on changes in endogenous gibberellins and cytokinins during floral development of mango. MATERIALS AND METHODS S a m p l i n g . - - Ten uniform six-year-old 'Dashehari' mango trees were selected.
Ten each of healthy and malformed panicles were tagged at panicle emergence stage on all sides of a tree. The samples of healthy and malformed panicles were collected at different intervals of their growth from all the trees. Samples were chopped, thoroughly mixed and then 20 g panicle tissue was drawn separately from healthy and malformed panicles on each sampling date (see Figs. 1 and 3) and the samples were kept at 4 -+ I°C in 80% methanol until needed. o f g i b b e r e l l i n s a n d c y t o k i n i n s . - - The sample was blended with 80% methanol at 4 + 1°C in a Waring Blendor. The mixture was extracted five times with 80% methanol for 24 h at 4 + I°C. The extracts o f each sample were combined and reduced in volume, at 40°C in vacuo. The ethyl acetate-soluble acidic fraction was tested for gibberellin-like activity (Pal and Ram, 1978). The aqueous and non-acidic ethyl acetate fractions were tested for cytokinin-like activity (Ram et al., 1983).
Extraction
o f g i b b e r e l l i n s . - - The ethyl acetate-soluble acidic fraction equivalent to 1 g fresh weight of tissue was applied in a 5-mm-wide band across a Whatman No. 1 paper strip (45 cm X 4.5 cm) and the solvent was allowed to descend 40 cm at 19--20°C. The solvent was benzene--acetic acid--water (4:2:1; v/v) (Bentley, 1963). Each chromatogram was transversely divided into 10 equal segments. The eluates were bioassayed. Paper chromatography
o f c y t o k i n i n s . - - The combined ethyl acetate-soluble neutral and butanol-soluble fraction equivalent to 1 g fresh weight was applied in a 5-ram-wide band across Whatman No. 1 chromatographic paper strip (45 cm X 10 cm). The solvent system employed was n-butanol--acetic acid--water (12:3:5; v/v, upper phase). The solvent was allowed to descend 40 cm at 24 -+ 1°C. Each chromatogram was transversely divided into 10 equal segments. The eluates were bioassayed.
Paper chromatography
G i b b e r e l l i n bioassay. - - Gibberellins were assayed by lettuce h y p o c o t y l growth test (Frankland and Wareing, 1960) using 'Great Lake'.
237
Cytokinin b i o a s s a y . - - Cytokinin activity was bioassayed by the soybean cotyledon callus culture test (Miller, 1965) using 'Ankur'. Zeatin was omitted from the basal medium when the eluates of the chromatograms were tested for cytokinin activity.
RESULTS
Figure 1 shows that in 1983 the total gibberellin content in healthy panicles decreased rapidly in February and slowly in March. A slight increase in gibberellin levels occurred after flowering was over in the first week of April at the mustard stage of the fruit. However, malformed panicles contained lower levels of gibberellin in February and higher levels in March-April than healthy panicles. The gibberellin content in malformed panicles increased sharply at full bloom in the month o f March, declined rapidly in April and reached a minimum in the first week of May, when flowering in malformed panicles was still continuing. Thereafter, it increased to a level in August--September which was similar to that of February --March in healthy
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Fig. 1. Changes in the levels of total gibberellins in healthy and malformed mango panicles from February to September as measured by lettuce hypocotyl growth test.
238
panicle. Some of the flowers produced on malformed panicles in August-September bore fruits. Thus, gibberellin content in malformed panicles was generally at higher levels than in healthy ones. Similar data were obtained in 1982. Figure 2 shows that cytokinin changes in healthy and malformed panicles followed a similar pattern, but cytokinin concentrations were always higher in malformed panicles than in healthy ones until the first week of April, when flowering ceased in healthy panicles, although malformed panicles continued flowering. The cytokinin levels in malformed panicles were at a low level from mid-April to mid-September. Figure 3A and B shows that on 4 February the chromatograms of healthy panicles contained three zones of cytokinin-like activity at Rf 0.20--0.60, 0.70--0.80 and 0.90--1.00, whereas chromatograms of malformed panicles contained only two zones, at Rf 0.00--0.30 and 0.50--0.70. The cytokinin activity at Rf 0.90--1.00 of healthy panicles was absent in the malformed panicles, but at Rf 0.50--0.60 it was conspicuously higher in malformed panicles than in chromatograms of healthy panicles. Although there was little difference in t h e Rrvalues of cytokinins of healthy and malformed panicles on 4 March {Fig. 3C and D), the malformed panicles had rather higher cytokinin activity than the healthy panicles. On 4 April (Fig. 3E and F), the healthy panicles had a very low cytokinin 0008
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Fig. 2. Changes in the levels of total cytokinins in healthy and malformed mango panicles from February to September as measured by soybean cotyledon callus growth test.
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Fig. 3. Distribution of cytokinin activity as measured by soybean cotyledon callus growth test in the methanolic extract of healthy (A, C, E) and malformed (B, D, F) panicles sampled on 4 February (A, B), 4 March (C, D) and 4 April (E, F) 1983. A fraction equivalent to 1 g fresh weight of tissue was paper-chromatographed in solvent system n-butanol --acetic acid--water (12:3:5, v/v, upper phase). Solid horizontal lines indicate the weight of the callus pieces in controls, and broken horizontal lines indicate the LSD at 5% level.
level ( R f 0 . 9 0 - - 1 . 0 0 ) , w h e r e a s extracts o f m a l f o r m e d panicles o f this date had an appreciable c y t o k i n i n activity at Rf 0 . 2 0 - - 0 . 6 0 and 0 . 7 0 - - 0 . 9 0 . DISCUSSION T h e pattern o f c h a n g e s in gibbereUin c o n t e n t o f d e v e l o p i n g m a l f o r m e d m a n g o panicles w a s d i f f e r e n t f r o m t h o s e in h e a l t h y panicles. L o w gibberellin c o n t e n t in February, a sharp increase to very high levels in March, f o l l o w e d by a sharp decline in May and rise thereafter, suggest t h e i n v o l v e m e n t o f
240
gibberellins in the differential growth pattern of malformed panicles (Majumder and Sinha, 1972; Pandey et al., 1974). The difference in pattern of rise and fall in gibberellin levels of malformed panicles compared to healthy ones may be due to synthesis of gibberellins by Fusarium moniliforme and other fungi reported to be present in malformed panicles (Summanwar et al., 1966; Ibrahim et al., 1975). Fusarium moniliforme is known for gibberellin synthesis (Stodola et al., 1955). Gibberellins are known to increase cell size, as was reported in malformed mango panicle (Pandey et al., 1977). Changes in the cytokinin levels of healthy and malformed mango panicles followed a similar pattern, but cytokinin concentrations were always higher in malformed panicles than in healthy ones. The qualitative differences between malformed and healthy panicles (Fig. 3) were probably due to the association of fungi reported to be present in malformed panicles (Summanwar et al., 1966; Ibrahim et al., 1975). We previously reported the involvement of malformin in the malformation of mango panicles (Ram and Bist, 1984). It is probable that the fungi reported to be present in malformed panicles may be synthesizing not only malformins but also gibberellins and cytokinins. ACKNOWLEDGEMENTS
The authors thank Dr. R.P. Chaudhary, Dean of Agriculture, Dr. S.C. Modgal, Director of Research, and Dr. R.P. Singh, Professor of Horticulture, for their encouragement during the course of the investigations.
REFERENCES Abou-Hussein, M.R., Fadl, M.S. and E1-Ghandour, M.A., 1975. Some morphological and physiological features of flowering malformation in mangoes. Egypt. J. Hortic., 2: 199--208. Anonymous, 1983. Mango cultivation. Indian Institute of Horticultural Research, Bangalore, India, Extension Bull. No. 9, pp. 22--23. Attiah, H.H., 1955. A new eriophyid mite of mango from Egypt. Bull. Soc. Entomol. Egypt, 39: 379--383. Bentley, A.J., 1963. Gibberellin-like substances in algae. Nature (London), 200: 453-455. Chadha, K.L., Pal, R.N., Prakash, O., Tandon, P.L., Singh, H., Singh, N.P., Rao, M.R.K. and Lal, B., 1979. Studies on mango malformation -- its causes and control. Indian J. Hortic., 36: 359--368. E1-Ghandour, M.A., Hamawi, H.A. and Fadl, M.S., 1976. Biological studies for exploring interaction between some native growth regulators and abnormal growth of mango shoots. Egypt. J. Hortic., 3: 69--82. Flechtmann, C.H.W., Kimati, H., Medcalf, J.C. and Ferre, J., 1970. Preliminary observations on mango inflorescence malformation and the fungi, insects and mites associated with it. An. de Esc. Super. Agric., "Luiz de Queiroz", Univ. Sao Paulo, 27: 2 8 1 - 2 8 5 . Frankland, B. and Wareing, P.F., 1960. Effect of gibherellic acid on hypocotyl growth of lettuce seedlings. Nature (London), 185: 255--256.
241 Ibrahim, A.N., Satour, M.M., E1-Tobshy, Z.M. and Abdel Sattar, M.A., 1975. Pathological and histological note on mango malformation in Egypt. Curr. Sci., 44: 443--444. Majumder, P.K. and Sinha, G.C., 1972. Studies on the effect of malformation on growth, sex ratio, fruit set and yield of mango. Acta Hortic., 24: 230--234. Mallik, P.C., 1963. Mango m a l f o r m a t i o n - symptoms, causes and cure. Punjab Hortic. J., 3: 292--299. Malo, S.E. and McMillan, R.T., Jr., 1973. A disease ofMangifera indica L. in Florida similar to mango malformation. In: Proc. 85th Annu. Meet. Fla. State Hortic. Soc., pp. 264--268. Miller, C.O., 1965. Evidence for the natural occurrence of zeatin and derivatives. Compounds from maize which promote cell division. Proc. Natl. Acad. Sci., U.S.A., 54: 1052--1058. Mishra, K.A. and Dhillon, B.S., 1979. Management of floral malformation of mango with planofix sprays. F o o d Farming Agric., 10: 318--319. Pal, S. and Ram, S., 1978. Endogenous gibberellins of mango shoot-tips and their significance in flowering. Scientia Hortic., 9 : 369--379. Pandey, R.M., Rathore, D.S. and Sirtgh, R.N., 1974. Hormonal regulation o f mango malformation. Curr. Sci., 43: 694--695. Pandey, R.M., Rao, M.M. and Pathak, R.A., 1977. Biochemical changes associated with floral malformation in mango. Scientia Hortic., 6: 37--44. Prasad, A., Singh, H. and Shukla, T.N., 1965. Present status of mango malformation disease. Indian J. Hortic., 22: 254--265. Ram, S. and Bist, L.D., 1984. Occurrence of malformin-like substances in malformed panicles and control of floral malformation in mango. Scientia Hortic., 23: 331--336. Ram, S., Sirohi, S.C. and Rathore, V.S., 1983. Naturally occurring cytokinins in mango. Aust. J. Plant Physiol., 10: 65--73. Schwartz, A., 1968. A new mango pest. Farming S. Afr., 44: 7. Shawky, I., Zidan, Z., E1-Tomi, A. and Dahshan, D., 1980. Flowering malformation in relation to vegetative growth of Taimour mangoes. Egypt. J. Hortic., 7 : 1--8. Singh, R.N., 1978. Am (Mango). In: Phal Vigyan (Fruit Science). Indian Council of Agricultural Research, New Delhi, pp. 113--115. Stodola, F.H., Raper, K.B., Fennell, D.I., Conway, H.F., Sohns, V.E., Langford, C.T. and Jackson, R.W., 1955. The microbiological production of gibberellins A and X. Arch. Biochem. Biophys., 54: 240--245. Summanwar, A.S., Raychaudhuri, S.P. and Pathak, S.C., 1966. Association of the fungus Fusarium moniliforme Sheld, with the malformation in mango (Mangifera indica L.). Indian Phytopathol., 19: 227--228.
235
EFFECT OF MALFORMATION ON CHANGES IN ENDOGENOUS GIBBERELLINS AND CYTOKININS DURING FLORAL DEVELOPMENT OF MANGO
L.D. BIST and SANT RAM Department o f Horticulture, College of Agriculture, G.B. Pant University of Agriculture and Technology, Pantnagar, Nainital, U.P. (India) Experiment Station Research Paper No. 3632 (Accepted for publication 4 June 1985)
ABSTRACT
Bist, L.D. and Ram, S., 1986. Effect of malformation on changes in endogenous gibberellins and cytokinins during floral development of mango. Scientia Hortic., 28: 235--241. Patterns of gibberellin content of developing malformed mango inflorescences were very different from those in normal inflorescences. Cytokinin changes in healthy and malformed tissues followed a similar pattern, but cytokinin concentrations were always higher in the malformed inflorescences. Some qualitative differences were detected between chromatographs of cytokinins from malformed and healthy inflorescences. Keywords: auxin ; cytokinin ; floral malformation; gibberellin ; inhibitor ; mango. Abbreviation: LSD = least significant difference.
INTRODUCTION M a l f o r m e d panicles o f m a n g o have short, t h i c k m a i n a n d p r i m a r y rachises w i t h excessive b r a n c h i n g , giving t h e panicle a c h a r a c t e r i s t i c c l u s t e r e d a p p e a r ance. T h e flowers o f m a l f o r m e d panicles are usually m a l e , sterile and bigger t h a n t h o s e f r o m h e a l t h y panicles, w i t h v e r y low p e r c e n t a g e o f h e r m a p h r o dite flowers. S u c h panicles v e r y s e l d o m set fruits. M o s t o f t h e m d r y up during t h e s u m m e r a n d h a n g as b l a c k e n e d b u n c h e s , b u t a f e w c o n t i n u e to g r o w until t h e n e x t season (Singh, 1 9 7 8 ; S h a w k y et al., 1980). This t y p e o f d i s o r d e r is a m a j o r p r o b l e m , causing h e a v y losses t o m a n g o g r o w e r s ( A t t i a h , 1 9 5 5 ; Mallik, 1 9 6 3 ; Prasad et al., 1 9 6 5 ; S c h w a r t z , 1 9 6 8 ; F l e c h t m a n n et al., 1 9 7 0 ; Malo a n d McMillan, 1 9 7 3 ; A n o n . , 1983). Studies c o n d u c t e d so far have n o t clearly revealed t h e cause or c o n t r o l o f floral m a l f o r m a t i o n o f m a n g o ( C h a d h a et al., 1979). P a n d e y et al. {1974)
0304-4238186/$03.50
© 1986 Elsevier Science Publishers B.V.
236 reported low auxin and high inhibitor activity in malformed mango panicles. The endogenous levels o f gibberellins in malformed tissues have been reported as both high (Abou-Hussein et al., 1975; Mishra and Dhillon, 1979} and low (E1-Ghandour et al., 1976). Recently, malformin-like substances have been reported in the malformed mango panicles (Ram and Bist, 1984}. No work has been done on endogenous levels of cytokinins of malformed panicles. Investigations were therefore undertaken into the effect of malformation on changes in endogenous gibberellins and cytokinins during floral development of mango. MATERIALS AND METHODS S a m p l i n g . - - Ten uniform six-year-old 'Dashehari' mango trees were selected.
Ten each of healthy and malformed panicles were tagged at panicle emergence stage on all sides of a tree. The samples of healthy and malformed panicles were collected at different intervals of their growth from all the trees. Samples were chopped, thoroughly mixed and then 20 g panicle tissue was drawn separately from healthy and malformed panicles on each sampling date (see Figs. 1 and 3) and the samples were kept at 4 -+ I°C in 80% methanol until needed. o f g i b b e r e l l i n s a n d c y t o k i n i n s . - - The sample was blended with 80% methanol at 4 + 1°C in a Waring Blendor. The mixture was extracted five times with 80% methanol for 24 h at 4 + I°C. The extracts o f each sample were combined and reduced in volume, at 40°C in vacuo. The ethyl acetate-soluble acidic fraction was tested for gibberellin-like activity (Pal and Ram, 1978). The aqueous and non-acidic ethyl acetate fractions were tested for cytokinin-like activity (Ram et al., 1983).
Extraction
o f g i b b e r e l l i n s . - - The ethyl acetate-soluble acidic fraction equivalent to 1 g fresh weight of tissue was applied in a 5-mm-wide band across a Whatman No. 1 paper strip (45 cm X 4.5 cm) and the solvent was allowed to descend 40 cm at 19--20°C. The solvent was benzene--acetic acid--water (4:2:1; v/v) (Bentley, 1963). Each chromatogram was transversely divided into 10 equal segments. The eluates were bioassayed. Paper chromatography
o f c y t o k i n i n s . - - The combined ethyl acetate-soluble neutral and butanol-soluble fraction equivalent to 1 g fresh weight was applied in a 5-ram-wide band across Whatman No. 1 chromatographic paper strip (45 cm X 10 cm). The solvent system employed was n-butanol--acetic acid--water (12:3:5; v/v, upper phase). The solvent was allowed to descend 40 cm at 24 -+ 1°C. Each chromatogram was transversely divided into 10 equal segments. The eluates were bioassayed.
Paper chromatography
G i b b e r e l l i n bioassay. - - Gibberellins were assayed by lettuce h y p o c o t y l growth test (Frankland and Wareing, 1960) using 'Great Lake'.
237
Cytokinin b i o a s s a y . - - Cytokinin activity was bioassayed by the soybean cotyledon callus culture test (Miller, 1965) using 'Ankur'. Zeatin was omitted from the basal medium when the eluates of the chromatograms were tested for cytokinin activity.
RESULTS
Figure 1 shows that in 1983 the total gibberellin content in healthy panicles decreased rapidly in February and slowly in March. A slight increase in gibberellin levels occurred after flowering was over in the first week of April at the mustard stage of the fruit. However, malformed panicles contained lower levels of gibberellin in February and higher levels in March-April than healthy panicles. The gibberellin content in malformed panicles increased sharply at full bloom in the month o f March, declined rapidly in April and reached a minimum in the first week of May, when flowering in malformed panicles was still continuing. Thereafter, it increased to a level in August--September which was similar to that of February --March in healthy
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Fig. 1. Changes in the levels of total gibberellins in healthy and malformed mango panicles from February to September as measured by lettuce hypocotyl growth test.
238
panicle. Some of the flowers produced on malformed panicles in August-September bore fruits. Thus, gibberellin content in malformed panicles was generally at higher levels than in healthy ones. Similar data were obtained in 1982. Figure 2 shows that cytokinin changes in healthy and malformed panicles followed a similar pattern, but cytokinin concentrations were always higher in malformed panicles than in healthy ones until the first week of April, when flowering ceased in healthy panicles, although malformed panicles continued flowering. The cytokinin levels in malformed panicles were at a low level from mid-April to mid-September. Figure 3A and B shows that on 4 February the chromatograms of healthy panicles contained three zones of cytokinin-like activity at Rf 0.20--0.60, 0.70--0.80 and 0.90--1.00, whereas chromatograms of malformed panicles contained only two zones, at Rf 0.00--0.30 and 0.50--0.70. The cytokinin activity at Rf 0.90--1.00 of healthy panicles was absent in the malformed panicles, but at Rf 0.50--0.60 it was conspicuously higher in malformed panicles than in chromatograms of healthy panicles. Although there was little difference in t h e Rrvalues of cytokinins of healthy and malformed panicles on 4 March {Fig. 3C and D), the malformed panicles had rather higher cytokinin activity than the healthy panicles. On 4 April (Fig. 3E and F), the healthy panicles had a very low cytokinin 0008
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239 HEALTHY PANICLE
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0'9
Fig. 3. Distribution of cytokinin activity as measured by soybean cotyledon callus growth test in the methanolic extract of healthy (A, C, E) and malformed (B, D, F) panicles sampled on 4 February (A, B), 4 March (C, D) and 4 April (E, F) 1983. A fraction equivalent to 1 g fresh weight of tissue was paper-chromatographed in solvent system n-butanol --acetic acid--water (12:3:5, v/v, upper phase). Solid horizontal lines indicate the weight of the callus pieces in controls, and broken horizontal lines indicate the LSD at 5% level.
level ( R f 0 . 9 0 - - 1 . 0 0 ) , w h e r e a s extracts o f m a l f o r m e d panicles o f this date had an appreciable c y t o k i n i n activity at Rf 0 . 2 0 - - 0 . 6 0 and 0 . 7 0 - - 0 . 9 0 . DISCUSSION T h e pattern o f c h a n g e s in gibbereUin c o n t e n t o f d e v e l o p i n g m a l f o r m e d m a n g o panicles w a s d i f f e r e n t f r o m t h o s e in h e a l t h y panicles. L o w gibberellin c o n t e n t in February, a sharp increase to very high levels in March, f o l l o w e d by a sharp decline in May and rise thereafter, suggest t h e i n v o l v e m e n t o f
240
gibberellins in the differential growth pattern of malformed panicles (Majumder and Sinha, 1972; Pandey et al., 1974). The difference in pattern of rise and fall in gibberellin levels of malformed panicles compared to healthy ones may be due to synthesis of gibberellins by Fusarium moniliforme and other fungi reported to be present in malformed panicles (Summanwar et al., 1966; Ibrahim et al., 1975). Fusarium moniliforme is known for gibberellin synthesis (Stodola et al., 1955). Gibberellins are known to increase cell size, as was reported in malformed mango panicle (Pandey et al., 1977). Changes in the cytokinin levels of healthy and malformed mango panicles followed a similar pattern, but cytokinin concentrations were always higher in malformed panicles than in healthy ones. The qualitative differences between malformed and healthy panicles (Fig. 3) were probably due to the association of fungi reported to be present in malformed panicles (Summanwar et al., 1966; Ibrahim et al., 1975). We previously reported the involvement of malformin in the malformation of mango panicles (Ram and Bist, 1984). It is probable that the fungi reported to be present in malformed panicles may be synthesizing not only malformins but also gibberellins and cytokinins. ACKNOWLEDGEMENTS
The authors thank Dr. R.P. Chaudhary, Dean of Agriculture, Dr. S.C. Modgal, Director of Research, and Dr. R.P. Singh, Professor of Horticulture, for their encouragement during the course of the investigations.
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