ABSTRACT Galls are specialized plant structures formed by the alteration of normal plant tissues by the galling organisms. Generally galls provide a food source to the insect for their growth and development. Present study elaborates the biochemical changes in leaf galls of Syzygium jambos due to the infection of Trioza jambolanae. The amount of total chlorophyll, carbohydrate, protein, phenol, amino acids and proline were compared in healthy and galled leaf extracts. Nutritive tissue, on which the insect feeds, contained high amount of phenol and proline whereas low amount of total chlorophyll, carbohydrate, protein and amino acids compared with healthy leaves. Our results indicate that distribution of biochemical defences in this psyllid gall differs significantly from the leaf tissue from which it is formed. This study suggests that the gall is manipulated by the insect to enhance its food and protective value. Keywords: Galls, Biochemicals, Nutritive tissue, Psyllids, Defence. REFERENCES Allen P J (1942). Changes in the metabolism of wheat leaves induced by infection with powdery mildew. Am.y. Bot., 29, 425. Ananthakrishnan T N (2001). Phytochemical defence profiles in insect-plant interactions. In: Insects and Plant Defence. Pp: 1-21. Dynamics Sci. Pub., USA. Anders F (1958). Amino sauren als gallener stofeeder Reblaus (Vi tens). Experientia 14:62-68. Arnon D I (1949). Copper enzymes in isolated chloroplasts. Polyphenol oxidase in Beta vulgaris. Plant Physiol. 24: 1-15. Bates L-S, Waldren R P and Teare I D (1973). Rapid determination of free proline for water stress studies, Plant and soil, 39, 205-208. Bray H G and Thorpe W V (1954). Analysis of phenolic compounds of interest in metabolism. Meth. Biochem. Anal. 1:27-52. Dasgupta M K (1988). Principles of Plant Pathology, Published by Allied Publishers Private Limited, pp. 470-500. Gibon Y, R Sulpice and F Larher (2000). Proline accumulation in conola leaf discs subjected to osmotic stress is related to loss of chlorophylls and to the decrease of mitochondrial activity. Physiol. Plant., 110: 469-76. Hare PD, Cress WA (1997). Metabolic implications of stress- induced proline accumulation in plants. Plant Growth Regulation 21, 79–102. Horsfall J and Dimond A (1957). Interactions of tissue sugar, growth substances and disease susceptibility. Zeitschrift für Pflanzenkrankheiten und Pflanzenschutz, vol. 64, no. p. 415-421. Isawa K (1985). Deterioration in the chemical composition and nutritive value of forage-crops caused by foliar diseases. VIII. Chemical composition and nutritive value of grass and legume leaves artificially killed by physical or chemical treatments. Bull. Natl. Grassland Res. Ins. 31: 73-80. Legrand M (1983). Phenylpropanoid metabolism and its regulation in disease. Pages 367-384. In: Biochemical Plant Pathology. J. A. Callow, ed. John Wiley & Sons, Chichester, UK. Lowry O R, Rosebrough R J, Farr A L and Randall R J (1951). Protein measurement with Folin-phenol reagent. J. Biol. Chem. 193:265-275. Mehrotra R S and Agarwal A (2003). Plant Pathology 2nd edi. Tata Mc Graw Hill Publishing com. Ltd. Miles P W (1968). Insect secretions in plants. Ann. Rev. Phytopath. 6:136-164. Miles P W and Lloyd J (1967). Synthesis of a plant hormone by the salivary apparatus of plant sucking bugs. Nature (London). 203: 801-802. Moftah A E and Michel B E (1987). The effect of sodium chloride on solute potential and protein accumulation in soybean leaves. Plant Physiol, 83, 238-240. Moore S and Stein W H (1948). Photometric ninhydrin method for use in chromatography of amino acids. Journal of Biological Chemistry. 176: 367-386. Purohit S D, Ramawat K G and Arya H C (1979). Phenolics, peroxidise and phenolase as related to gall formation in some arid zone plants. Curr. Sci. 148: 714-716. Ride J P (1983). Structural barriers in defence. Pages 215-236 in: Biochemical Plant Pathology. J. A. Callow, ed. John Wiley & Sons, Chichester, UK. Scott F G (1960). Effect of super optimal boron levels on respiration and carbohydrate metabolism of Helianthus annuus L. Plant Physiol. 35: 653-668. Szabados L, Savouré A (2010). Proline: a multifunctional amino acid. Trends Plant Sci 15: 89–97. Uritani I (1976). Protein metabolism. In: Encyclopedia of Plant Physiol. (New Series). R. HEIT-Fuss and P. H. WILLIAMS (Eds.). Springer-Verlag, Heidelberg and New Y or k. 4:509-521. Verbruggen N, Hermans C (2008). Proline accumulation in plants: a review.Amino Acids 35: 753–759. Vidhyasekaran P (2002). Bacterial disease resistance in plants: molecular biology and biotechnological applications. Binghamton, NY: Haworth Press.