Proceedings of The Fourth International Iran & Russia Conference 113 Growth stimulation and enhanced invertase activity induced by salicylic acid in tea cuttings (Camellia sinensis L.). Shirin Haddad Kaveh , Françoise Bernard , Keivandokht Samiee Shahid Beheshti university, Faculty of Sciences, department of Biology, Plant Physiology and Biotechnology Laboratory, Tehran, Iran, Phone: +98 021 240 31 51 Email: S_H_Kaveh@yahoo.com Abstract Salicylic acid(SA) acts as an endogenous signal for the induction of systemic acquired resistance (SAR) in plants infected by pathogens. The application of SA promotes the SAR process and consequently could interfere on the growth of plants with such an increased resistance. The influence of SA application on the growth and invertase activity of one year old tea cuttings (Camellia sinensis L.) was investigated. Tea cuttings, grown on compost in a growth chamber, were sprinkled with Hoagland medium of SA every five days. After 28 days of growth, leaves were harvested and used for growth and total soluble sugar (TSS) measurements. Leaf invertase activity was measured spectrophotometrically . The data were analysed statistically. Very low dose of SA considerably enhanced the growth and carbohydrate metabolism of tea cuttings. Addition of 50 μM SA produced the most remarkable effects. There was a 2 fold significant increase (p<0.05) in leaf area, leaf fresh weight and leaf dry weight. Leaf TSS were also double by this treatment. Invertase activity in SA treated cuttings was higher than in control with a significant increase (x 3.4) for 50 μM SA (p<0.05). These results suggest that it will be profitable to experiment very low dose SA application at the field culture level for the improvement of tea cuttings’ plantation. Key words : Camellia sinensis L., cutting, growth, invertase, salicylic acid Introduction Salicylic acid (SA) is now considered as a new plant hormone involved in a number of plant responses to environmental stresses (Shah and Klessig, 1999). It is a key molecule of pathogen plant response (Dempsey et al., 1999). SA-induced local hypersensitive response (HR) and systemic acquired resitance (SAR) against pathogen attack are proposed to be mediated through the inhibition of catalase, which subsequently raises intracellular H 2 O 2 concentration (Dempsey et al., 1999 ). SA improved the chilling resistance of maize (Jandra et al., 1999) , the acclimation of tomato to salinity stress (Tari et al., 2002) and the resistance of wheat seedlings to water deficit (Bezrukova et al., 2001; Sakhabutdinova et al., 2003). Elevated levels of endogenous SA were notified in response to wounding, UV, ozone or pathogen attack (Zhang and Klessig , 1998; Leon et al., 1995). The plant response to stresses, including that involved in SAR depends on the sugar status of the cell. Elevated levels of Hexose have been implicated as signals for the induction of plant defense responses (Herber et al., 1996). If hexose signalling of defense expression occurs, it is likely related to the increased expression of vacuolar invertase (Blee and Anderson, 1998). As it has been shown that SA affects the uptake of sucrose through an effect on the ATPase activity (Bourbouloux et al., 1998) one may expect to have repercussion in the hexose level and the invertase activity in SA treated tissues. In the present study, the interaction between SA and the carbohydrates metabolism was investigated by measuring leaf invertase activity, soluble sugars and growth of Camellia cuttings.