M. Aghdaei; S.H. Nemati; L. Samiei; A. Sharifi
Abstract
Introduction: Pepino (Solanum muricatum Aiton) is a diploid herbaceous plant belongs to the Solanaceae family, which is growing in subtropical zone, originates from Andes in South America. It is commercially grown for its fruit, which is appreciated not only for food but also for its appearance, in South ...
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Introduction: Pepino (Solanum muricatum Aiton) is a diploid herbaceous plant belongs to the Solanaceae family, which is growing in subtropical zone, originates from Andes in South America. It is commercially grown for its fruit, which is appreciated not only for food but also for its appearance, in South American countries, including Bolivia, Colombia, Ecuador and Peru, as well as in countries such as New Zealand and Australia. Pepino is propagated by seed, cutting, and tissue culture methods. Most pepino cultivars are sexually fertile and produce viable seeds, but their seeds have poor germination and high level of heterozygosis causing to highly variable plants. Both mentioned negative aspects have limited the mass production of this plant through seed. In this case, stem cutting is used as the most common way of propagating pepino led to transmission of viral diseases and increasing propagation costs as two main limiting factors of pepino propagation. So, micropropagation systems are a promising tool to produce disease-free clonal plant material with low costs. Therefore, the present study was aimed to assess the effect of different media and plant growth regulators on micropropagation traits of pepino.
Materials and Methods: Three separate experiments were carried out in institute of plant sciences of Ferdowsi University of Mashhad in 2016. Pepino seeds were bought from company of Plant World Seed, UK, were cultivated on MS medium. Grown plants were used as source of providing explants. Four mediums, including MS, ½ MS, SH and B5 were used to determine the best culture medium for shoot regeneration of pepino using single node explant. A factorial experiment was conducted based on a completely randomized design. Some growth properties such as number of shoots, shoot length, number of roots, root length, leaf number and leaf length were evaluated after two and four weeks. In proliferation experiment, MS medium was compared with MS supplemented with different concentrations of BA (0.5, 1 and 2 mg L-1) and Kin (0.5, 1 and 2 mg L-1) applied as combined treatments, and also BA used alone at concentrations of 2, 4 and 6 mg L-1 that was conducted based on a completely randomized design. For rooting of explants, an experiment was conducted based on a completely randomized design containing of two concentrations of IBA (at 0.3 and 0.6 mg L-1) and three concentrations of NAA (at 0.3, 0.6 and 0.9 mg L-1) in MS medium. Some growth properties including root number and length, root density and root quality were evaluated after four weeks
Results and Discussion: Results indicated that micropropagation rate of pepino was affected by culture medium type. The highest shoot length, number of root, root length and leaf number were obtained in MS medium, although statistically there was no significant difference between MS and ½ MS media. The highest number of shoots and leaf length were observed in MS medium, which led to a significant difference with other media (½ MS, SH and B5). Overall, Based on obtained results MS medium was the best culture medium for micropropagation of pepino using single node. In the proliferation experiment, the highest shoot and leaf number and plant color were obtained with using 2 mg L-1 BA + 1 mg L-1 Kin, whereas the highest shoot length and leaf length were observed in the 1 mg L-1 BA + 2 mg L-1 Kin and 1 mg L-1 BA+1 mg L-1 Kin treatments, respectively. Increasing in concentration of BA up to 2 mg L-1 in combination with Kin had a positive effect on shoot proliferation, while applying BA at concentration 2, 4 and 6 mg L-1 alone led to decrease in proliferation. Results obtained from rooting experiment showed that the highest root number, root density and root quality were obtained using IBA at the concentration of 0.6 mg L-1, whereas the highest root length was observed by applying IBA at concentration of 0.3 mg L-1, which led to a significant difference with other treatments. Furthermore, results indicated that the effect of IBA on rooting of pepino microshoots was more than NAA.
Conclusion: Generally, the best results were obtained by MS medium, 2 mg L-1 BA with 1 mg L-1 Kin for shoot proliferation, and IBA at concentration of 0.6 mg L-1 for the rooting of pepino nodal segments.
sakineh bagheri; dariush davoodi; mohammad esmaeel amiri; mina bayanati; mehrnaz entesari
Abstract
Introduction: The GF677(Prunusamygdalus×P. persica) is a peach rootstock tolerant to Fe deficiency. Nowadays, it is mainly propagated through micro propagation. Widening and undesirable growth of leaves as well as poor rooting are major problems during its in vitro culture. GF-677 is one of the most ...
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Introduction: The GF677(Prunusamygdalus×P. persica) is a peach rootstock tolerant to Fe deficiency. Nowadays, it is mainly propagated through micro propagation. Widening and undesirable growth of leaves as well as poor rooting are major problems during its in vitro culture. GF-677 is one of the most suitable rootstocks for almond and peach used in calcareous soils to overcome lime-induced chlorosis. Therefore, in vitro micro propagation is important for commercial purposes. Using liquid medium, it may be possible to reduce costs to a level lower than solid medium and liquid medium is better than solid medium in growth. Both the brand and concentration of agar also affect the chemical and physical characteristics of a culture medium. One of the main factors on micropropagation is hormone specially BAP. Furthermore, shoot branching depends on the initiation and activity of axillary meristems, which usually controlled by cytokinin. The rooting stage, the induction of roots on explants from in vitro culture is crucial part in any micropropagation process. The ability of plant tissue to form adventitious roots depends on interaction of many exogenous and endogenous factors, including hormone. Most reports of adventitious root induction of woody species have involved treatments with exogenous auxins such as IBA, NAA or IAA. Dimassi-Theriou (1995) for rooting of GF-677 compared different culture media and results on the rooting of these rootstocks depend on the type of medium culture.
Materials and Methods: Axillary shoot of GF677 was cultured on both liquid and solid media. In proliferation step both liquid and solid media (MS, DKW and WPM) were used in primary stages of the experiment. Medium containing BAP 1mg.land-1 NAA 0.1mg.l-1. Under growth chamber conditions, light intensity was maintained at 2500-3000 lux with an 8-hour dark period. For rooting, 3-4 cm-long shoots from previous culture were transferred to 1/2 MS medium containing IBA (0, 0.5, 1 and 1/5mg.l-1) and 6 , 0 g l-1 agar. Darkness during the last week of the rooting phase has been shown to be necessary in stimulating rooting in some woody species. Note that the room temperature was maintained at 25°C during this experimental stage. The experiment was carried out based on factorial adopted completely randomized design with 5 replications per treatment. Explants shoot lengths, shoot numbers, root lengths and root numbers were recorded after 4 weeks which propagated plants via tissue culture were transferred to soil medium using 50% peat and 50% perlit mixture.
Results and Discussion:
Shoot proliferation: The observation indicates that there were significant differences between solid and liquid media. Best results were achieved for proliferation by liquid medium and among which MS obtained the highest frequency. The highest number of shoot was observed in MS medium and the lowest number of shoot was observed in WPM medium. Increasing mineral concentration resulted in increased multiplication, growth rate and total mineral uptake by GF677 explants.
Root initiation of in vitro: Various concentrations of IBA showed significant differences. The maximum number of roots and root length were observed in the medium containing 0.5 mg.l-1 IBA. The best results were obtained for rooting in liquid 1/2 MS supplemented with 0.5 mg.l-1 IBA. The mean survival of the plants were transferred to liquid medium (75%) and mean survival of the plants were transferred from the solid culture medium (50%).
Conclusion: In conclusion, a micropropagation system for GF677 has been worked out utilizing nodal explants. Our investigation showed that the liquid MS medium with 1 mg.lit-1 BAP was the best for proliferation of GF677 and micropropagated plants were rooted and established in soil successfully. WPM medium is higher in chloride level which has been reported to result in growth depression in plants due to inhibited nutrient uptake, transport and utilization of nutrients variation in multiplication and growth of explants can be explained on the basis of water potential and mineral availability to the explants in the liquid medium. Many investigators have reported that IBA has a better effect on promoting adventitious root formation in comparison to IAA. The best results were obtained for rooting in 1/2 MS supplemented with 0.5 mg. l/1 IBA.
