In vitro rooting and biochemical parameters in the cherry rootstocks CAB-6P and Gisela 6 using L-methionine

Authors: VIRGINIA SARROPOULOU, KORTESSA DIMASSI-THERIOU, IOANNIS THERIOS

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 process in both rootstocks. The increased levels of proline in the roots of CAB-6P with the treatments of 0.5 mg L^{-1} IBA combined with 1 and 2 mg of L^{-1} L-methionine, as opposed to IBA alone, show osmotic or oxidative stress. In the Gisela 6 explants, the decline in proline levels in the roots indicates a mechanism of osmoregulation and osmotic adjustment, which seems to be localized only in the roots and not in the leaves.

Keywords: Auxins, carbohydrates, cherry rootstocks, chlorophyll content, in vitro rooting, proline

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