l-methionine influences in vitro root regeneration, total chlorophyll, total carbohydrate and endogenous proline content in the sweet cherry rootstock MxM 14 (Prunus avium × Prunus mahaleb)

• The 1 mg/L IBA plus 0.5 mg/L methionine treatment was proved to be ideal on rooting.
• Methionine with 2 mg/L IBA had an inhibitory effect on shoot fresh and dry weight.
• Optimum leaf chlorophyll content with 2 mg/L IBA plus 1 mg/L methionine.
• IBA alone and with l-methionine doubled the carbohydrate concentration in leaves.
• Increased proline concentration in leaves with low (0.5 mg/L) l-methionine.

In the present study, the effects of indole-3-butyric acid (IBA) separately and simultaneously with l-methionine on the morphogenic and biochemical responses in the cherry rootstock MxM 14 (Prunus avium × Prunus mahaleb), from shoot tip explants, were investigated. Best rooting results were achieved with 1 mg/L IBA plus 0.5 mg/L l-methionine. The incorporation of the amino acid in the Murashige and Skoog (MS) medium, greatly enhanced the promotive effect of the auxin on rooting, exhibiting a synergistic action. The supplementetion of explants with l-methionine did not influence their shoot length, for each IBA treatment. On the other hand, l-methionine when combined with the highest IBA concentration (2 mg/L) had an inhibitory effect on shoot fresh and dry weight. l-methionine significantly affected chlorophyll, carbohydrate and proline concentration. The maximum leaf chlorophyll concentration was recorded with 2 mg/L IBA plus 1 mg/L l-methionine. IBA alone or combined with l-methionine doubled the leaf carbohydrate concentration. Moreover, proline concentration in leaves was significantly increased with low (0.5 mg/L) l-methionine, irrespective of IBA concentration. In roots, the combined effect of 0.5 mg/L IBA with 0.5 mg/L l-methionine and the 1 mg/L IBA plus 1 mg/L l-methionine treatment led to elevated levels of endogenous proline and total carbohydrates, respectively, in comparison to the control. Taking into account the different parameters examined, chlorophyll and carbohydrates appeared as the most accurate biochemical markers of the rooting process in the MxM 14 rootstock.