A new protocol for in vitro regeneration through direct somatic embryogenesis for two muskmelon cultivars (Cucumis melo L., "Mashhadi" and "Eivanaki") is reported. Somatic embryos were obtained culturing 4- and 8-day-old cotyledons, seeds, and hypocotyls on Murashige and Skoog medium supplemented with three different hormonal combinations never tested so far for melon (naphthoxyacetic acid (NOA) + thidiazuron (TDZ), NOA + 6-banzylaminopurine (BAP), and 2,4-dichlorophenoxyacetic acid (2,4-D) + N-(2-chloro-4-pyridyl)-N'-phenylurea (4-CPPU)). Results were compared with those obtained when explants were cultivated in the presence of 2,4-D + BAP, previously used on melon. Embryogenesis occurred more successfully in 4-day-old cotyledons and seeds than hypocotyls and 8-day-old cotyledons. The best result was achieved with NOA + BAP. Genotypes significantly affected embryogenesis. The number of embryos in "Eivanaki" was significantly higher than that in "Mashhadi." Embryo proliferation when explants were maintained in jars (9.3%) was found to be higher compared to that in petri dishes. For the first time, genetic stability of regenerated melon plants was evaluated using inter-simple sequence repeat markers. Polymerase chain reaction (PCR) products demonstrated a total of 102 well-resolved bands, and regenerants were 93% similar compared to the mother plant. Somaclonal changes during embryogenesis were evaluated by flow cytometry, showing 91% of the same patterns in regenerated plants. The results suggest that the new hormone components are effective when applied for in vitro embryogenesis of muskmelon as they show a high frequency in regeneration and genetic homogeneity.
Juniperus sabina is an interesting species for forest restoration and ornamental purposes. The seeds of this plant have several types of dormancies; therefore, seed propagation is difficult and time consuming. The production of cuttings can be an alternative way to produce plants more quickly. The main objective of this experiment was to determine the best propagation conditions (indole butyric acid dose, substrate, and season) for this species using stem cuttings. Rooting performance of the cuttings was evaluated based on the rooting percentage (%), root biomass, and specific root length (SRL). In addition, we examined the internal composition (auxin and peroxidase content) in treated stem cuttings. Cuttings were pretreated with five doses of indole butyric acid (IBA; 0 (control), 1000, 2000, 4000, and 8000 ppm) and were rooted in four substrates (perlite, perlite-cocopeat, pumice, and mixed substrate) during the four seasons (winter, spring, summer, and autumn). The best treatments, with more than 60% rooting, were applied in spring, and IBA at 1000 ppm in perlite–cocopeat substrate obtained 62% rooting. The highest rooting percentage correlated with the highest root biomass production and the lowest SRL. IBA pretreatment decreased the concentration of peroxidase in spring (coinciding with maximum rooting), representing an indicator of rooting performance. Based on these results, we recommend a new protocol for Juniperus sabina production: (i) prepare cuttings in spring, (ii) treat cutting bases with 1000 ppm IBA, and (iii) plant cuttings in a substrate of perlite–cocopeat (1:1).
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