Effects of the exogenous polyamines on micropropagation of cherry rootstocks

In the present study, the effects of the 3 polyamines (PAs); putrescine (put), spermidine (spd) and spermine (spm) on micropropagation in CAB-6P, Gisela 6 and MxM 14 cherry rootstocks were investigated. In CAB-6P, shoot number (1.5) and shoot multiplication percentage (50%) were highest with 1 mg/l spd whereas shoot length was maximum with put irrespective of concentration. In Gisela 6, 1 mg/l spd exhibited the maximum shoot number (2) and shoot multiplication percentage (55.56%). In MxM 14, none of the 3 PAs resulted in multiple shoot production, In CAB-6P, root number (4) and rooting percentage (45.45%) were highest with 1 and 2 mg/l put, respectively, whereas 1 mg/l spd resulted in the greatest root length (160 mm). In Gisela 6, 2 mg/l put enhanced root number and root length, whereas rooting percentage was diminished by all 3 PAs. In MxM 14, root number (6.33) and rooting percentage (100%) were greatest with 1 mg/l put and 1 mg/l spm, respectively. In all 3 cherry rootstocks, PAs did not augment chlorophyll content. In CAB-6P, PAs resulted in reduction of leaf carbohydrate and proline levels and activation of mechanism of osmoregulation and osmotic adjustment in leaves. In Gisela 6, leaf carbohydrate levels were raised with 0.5 mg/l spm or 1 mg/l spd. Among the 3 PAs, only spd raised leaf proline content, while the content in roots was increased by 1 mg/l put, showing that PAs cause some kind of stress to the explants. In MxM 14, spd and spm augmented leaf carbohydrate levels, while in roots, only spm at 0.5 mg/l increased carbohydrate content. PAs hardly affected root proline content. It seems that in Gisela 6 and MxM 14, spd and spm increase the leaf carbohydrate content, whereas in CAB-6P all 3 PAs led to depleted leaf carbohydrate levels. The different responses among the 3 cherry rootstocks to PAs concerning shoot and root attributes are genotype-dependent.