vitro, the amino acids glutamic acid, aspartic acid, alanine, glutamine, proline, serine, and arginine induced rooting of explants in the presence of a-naphthalene acetic acid (Kamada and Harada 1979). Furthermore, it was found that while proline (10-200 mg L -1 ) increased the rooting percentage and number of roots per rooted explant of sweet cherry (Prunus avium L.) and sour cherry (Prunus cerasus L.), the root length was reduced (Baraldi et al. 1988).The different forms of nitrogen as well as its proportion can influence a number of factors in various in vitro cultures, such as cell division, the growth and development of somatic embryos, chlorophyll content, ribulose-1, 5-bisphosphate carboxylase/oxygenase activity, the electron transport rate, the photosynthetic rate, fresh mass, soluble protein concentration, and the osmotic pressure of the cell sap (Mashayekhi-Nezamabadi 2000). It has been reported that reduced nitrogen forms, particularly amides and amino acids, can improve cell proliferation, as well as regeneration in specific genotypes (Vasudevan et al. 2004).Methionine, a sulfur-containing amino acid, is a precursor of ethylene biosynthesis in plant tissues (Yang 1985). Besides its function as a protein constituent and its central role in the initiation of mRNA translation, methionine indirectly regulates a range of cellular processes as the precursor of S-adenosylmethionine (SAM) (Amir et al. 2002). Not only is SAM the primary biological methyl-group donor, but it is also the precursor of plant metabolites, including ethylene, polyamines, vitamin B 1 , and the iron chelator mugineic acid (Sun Abstract: In the present study, the effects of indole-3-butyric acid (IBA) alone and in combination with L-methionine were investigated on the morphogenic and biochemical responses in the shoot tip explants of the cherry rootstocks CAB-6P (Prunus cerasus L.) and Gisela 6 (Prunus cerasus × Prunus canescens). The best results for roots, regarding their number and the fresh and dry weight, were obtained with 2 mg L -1 IBA in both rootstocks. Maximum rooting percentage was with the combination of 2 mg L -1 IBA and 0.5 mg L -1 L-methionine. Root length was greatest in the control plants. L-methionine had an inhibitory effect on the leaf chlorophyll content of the CAB-6P rootstock and no effect in Gisela 6. L-methionine with the lowest IBA concentration (0.5 mg L -1 ) exhibited elevated levels of proline in the roots of the CAB-6P rootstock and depleted levels in Gisela 6. For the Gisela 6 rootstock, the leaf carbohydrate concentration was highest with 2 mg L -1 of IBA, whereas in the roots it was highest in the control. For the CAB-6P rootstock, the leaf carbohydrate concentration was not influenced by IBA with L-methionine, whereas the highest carbohydrate concentration in the roots was with the combinations of 0.5 mg L -1 IBA and 1 and 2 mg L -1 L-methionine. Taking into account the different parameters examined, it appears that chlorophyll and carbohydrates are the most accurate biochemical markers of the rooting ...
