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Yaser Hassan Dewir, Abdulhakim A. Aldubai, Salah El-Hendawy, Abdullah A. Alsadon, Mayada Kadry Seliem and Yougasphree Naidoo

A method for micropropagation of Conocarpus erectus through axillary shoot proliferation is presented. Shoot tips were excised from adult donor tree and cultured for 4 weeks on Murashige and Skoog’s (MS) medium supplemented with 3 mg·L−1 gibberellic acid (GA3) to induce sprouting of shoots and formation of axillary shoots. Conocarpus erectus shoots were cultured for 6 weeks on MS medium supplemented with different concentrations and combinations of plant growth regulators (PGRs) and proliferation of the shoots was monitored. The type and concentration of cytokinins applied had a significant influence on shoot proliferation responses. Supplementation with 6-benzylaminopurine (BAP) increased the rate of shoot proliferation compared with other cytokinins. The use of BAP in combination with auxins such as indole-3-butyric acid (IBA) and naphthalene acetic acid (NAA) resulted in an increased number of shoots per explant compared with treatment with BAP alone. A combination of 2 mg·L−1 BAP and 0.5 mg·L−1 IBA produced the highest number of axillary shoots (7.8 shoots/explant). The best rooting medium was full-strength MS medium supplemented with 1 mg·L−1 IBA; this treatment yielded 80% rooting with an average of 3.5 roots per plantlet. All regenerated plantlets were successfully acclimatized to greenhouse conditions.

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Yaser Hassan Dewir, Abdulhakim A. Aldubai, Rashid Sultan Al-Obeed, Salah El-Hendawy, Mayada Kadri Seliem and Khadija Rabeh Al-Harbi

Plant tissue culture offers opportunities for the rescue and conservation of endangered plant species. Here, we report the successful in vitro propagation of Dracaena ombet, an endangered plant. Several physical and chemical seed treatments were evaluated to develop a propagation approach. Germination of D. ombet seeds was monitored for 16 weeks by placing them onto Murashige and Skoog (MS) medium. Maximum seed germination (20%) was recorded when seeds were soaked-scarified, whereas all other treatments did not result in seed germination. Fragmented (longitudinally bisected) and intact in vitro shoots were cultured onto MS medium supplemented with various concentrations of 6-benzylaminopurine (BAP) and indole butyric acid (IBA) to induce axillary shoots. Longitudinal fragmentation of explants had a greater effect than the intact explants for shoot proliferation when cultured onto medium containing plant growth regulators. Fragmented shoots cultured onto MS medium supplemented with 2 mg·L−1 BAP and 0.5 mg·L−1 IBA treatment resulted in the highest amount of axillary shoots (seven shoots per explant). The intact shoots had the highest axillary shoots (1.8 shoots per explant) when cultured onto a medium supplemented with a combination of 1 mg·L−1 BAP and 0.5 mg·L−1 IBA. One hundred percent rooting was obtained using half strength MS medium supplemented with 0.5 or 1 mg·L−1 IBA. With full strength MS medium, a maximum rooting of 60% was obtained with 1 mg·L−1 IBA or naphthalene acetic acid (NAA) addition. The plantlets were acclimatized to ex vitro conditions with a 95% survival rate. This study offers a simple method for in vitro propagation of D. ombet, which is valuable to enable conservation of this endangered species.

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Asma Alhussein Alawaadh, Yaser Hassan Dewir, Mona S. Alwihibi, Abdulhakim A. Aldubai, Salah El-Hendawy and Yougasphree Naidoo

The present study aimed to optimize the micropropagation of lacy tree philodendron using shoot tip explants. Axillary shoot regeneration was investigated in Murashige and Skoog (MS) medium with different types and concentrations of plant growth regulators, varied levels of MS medium salt strength, sucrose concentration, and light intensity and culture type. Adding 6-benzylaminopurine (BAP; 1 mg·L−1) significantly increased shoot multiplication compared with other cytokinins, and the combination of cytokinins and auxins [indole-3-butyric acid (IBA) and naphthalene acetic acid (NAA)], yielded more shoots than cytokinins alone, with the greatest number of axillary shoots (11.4 per explant) obtained using both BAP (1 mg·L−1) and IBA (0.5 mg·L−1). In addition, the use of half-strength salt concentrations significantly reduced shoot multiplication, and high sucrose concentrations (>30 g·L−1) reduced explant growth. High light intensity also reduced shoot multiplication and growth, owing to photoinhibition, and shoot multiplication was more efficient in gelled culture, whereas shoot growth was greater in liquid/bioreactor culture. The best rooting success (100%) and greatest root number and fresh weight were obtained using MS medium supplemented with NAA (1–2 mg·L−1). The resulting plantlets were successfully acclimatized, with a survival rate of 100%, and were morphologically similar to the mother plant.