عنوان مقاله [English]
Background and Objectives
Red flesh apple belongs to Malus niedzwetzkyana of Rosaceae family, it has high levels of important phytochemicals like antioxidants, flavonoids and anthocyanins in its cortex, which in addition to attractiveness, it also is a source of benefit compound. The aim of the present investigation was to optimize efficient protocols for micro propagation of red flesh apple, in order to use the results in future breeding strategies.
Materials and Method
During the early spring, stem cuttings of growing red flesh apple trees were surface-sterilized in 70% ethanol and 50% sodium hypochlorite, then Sterilized samples were placed in the test tubes containing MS medium supplemented with 2 µM BAP. At the proliferation stage, interactive effects of BAP (0, 2, 4, 6 M) and GA3 (0, 3, 6 M) were investigated on various aspects of proliferation (multiplication rate, vegetative growth characteristics such as number of produced shoots per explant, shoots length, leaf numbers and the fresh and dry weight of explants). At rooting stage, the effect of different concentration of IBA or NAA (0, 1, 2, 3,4 µM) were compared on the percent of rooting, number of roots per explant and length of roots. At acclimatization stage, the plantlets were transferred into pots with a volume of 200 ml containing sterile compound at the greenhouse condition.
The results showed that there was a significant difference between the effect of different concentrations of BAP and GA3 on micro propagation of red flesh apple. The best result in proliferation (7.9 of axillary shoots after 8 months) was obtained from explants that were cultured in medium containing 4 M BAP and 3 M GA3. At rooting stage, the maximum rooting percent (85.2%) was obtained in the medium containing 3 M IBA. In addition, rooted explants from IBA treatments were successfully acclimatized (100%) in the greenhouse but rooted explants in NAA treatments were weak in acclimatized stage (40%).
Measuring the growth rate is the major economic parameter for successful plant production at in vitro conditions, which is usually characterized by the number of axillary shoots, number of regenerated leaves and increase in the length of shoots and fresh and dry weight, and we obtained the highest growth rate of red flesh apple in the culture medium containing 4 μM of BAP. The efficiency of BAP as an important cytokinin in apple proliferation has been reported in other studies too. The results of the present investigation showed that highest rooting percent was obtained from culture medium containing 3 μM of IBA. In addition, morphology of roots was varied in callus formation and longitudinal growth and the samples that were rooted in IBA treatments had stronger roots than the rooted samples in NAA treatments. It seems exposure to NAA instead of IBA, stimulates indirect organogenesis and produced undesirable side effects on roots, such as callus formation which can cause plantlets weakness during the period of acclimatization.