In Vitro Micropropagation of Industrially and Medicinally Useful Plant Aloe trichosantha Berger Using Offshoot Cuttings

Aloe monticola Reynolds: A refugee of the mountains - contributing towards its conservation through in vitro propagation

In vitro micropropagation study of Aloe monticola Reynolds was conducted using offshoots in Murashige and Skoog (MS) media enriched with plant growth regulators (PGRs). Initiation experiment, carried out by culturing sterilized explants in full-strength MS media enriched with 0.0-1.0 mg/L benzyl amino purine (BAP) alone and in combination with 0.10 mg/L indole-3-butyric acid (IBA), resulted in 89 - 100 % healthy and live (i.e., initiated) explants in 9-29 days. Regeneration study, conducted by culturing initiated explants in full-strength MS media supplemented with 0.0-3.0 mg/L BAP alone and in combination with 0.50 mg/L IBA, showed that treatments enriched with 1.0-3.0 mg/L BAP in combination with 0.50 mg/L IBA yielded better shooting responses than the rest of the treatments. The rooting responses of the shoots were also tested by culturing in half-strength MS media enriched with 0.0-4.0 mg/L NAA alone and in combination with 0.25 mg/L IBA. Better rooting responses were observed in treatments supplemented with 1.0-4.0 mg/L NAA in combination with 0.25 mg/L IBA with two exceptions. The responses of A. monticola plantlets to primary and secondary acclimatization in greenhouse, nursery shade, and direct sunlight in coco peat, composted soil, and manured soil were excellent - with survival percentages of 90-98 %. The findings of this empirical research are important for developing refined protocol of in vitro micropropagation of this ecologically important but endangered plant.

In vitro micropropagation of Aloe elegans Tod. using offshoot cuttings

OBJECTIVE

Aloe elegans Tod. is an ecologically, environmentally, medicinally, and commercially useful aloe species in Ethiopia and Eritrea. Unfortunately, it is highly threatened due to industrial and urban expansion and traditional mining and agricultural activities. As a consequence, it is included in the IUCN List of Threatened Species since 2013. The plant is getting thinly populated in many parts of the Tigrai floristic region since it is being exploited for traditional and commercial purposes. Therefore, this study was aimed to develop a reproducible, large-scale micropropagation protocol using offshoot cuttings in Murashige and Skoog (MS) media enriched with plant growth regulators (PGRs).

RESULTS

Sterilized explants cultured in full-strength MS media enriched with 0.25 mg/L benzyl amino purine (BAP) and 0.10 mg/L naphthaleneacetic acid (NAA) resulted in 100% healthy and live (i.e., initiated) explants after four weeks of initiation study. Unsupplemented initiation media (control) yielded only 14.3% initiated explants. The initiated explants were tested for their shooting response to produce microshoots by incubating in different concentrations and combinations of BAP and NAA for four weeks. Fewer days to shooting (13.0 ± 1.0 days), higher mean shoot number (5.0 ± 1.0), and higher mean shoot length (9.20 ± 2.35 cm) were observed with 1.0/0.50, 1.0/0.25, and 1.0 /0.50 mg/L BAP/NAA combinations, respectively. The rooting responses of the microshoots toward producing plantlets were also tested by incubating them in half-strength MS media enriched with different concentrations of NAA and indole-3-butyric acid (IBA) for four weeks. Fewer mean days to rooting (12.0 ± 1.0 days), higher mean root number (8.0 ± 4.0), and higher mean root length (7.53 ± 3.03 cm) were observed in MS media enriched with 0.75, 0.75, and 1.25 mg/L IBA, respectively. The responses of A. elegans plantlets to primary (in greenhouse) and secondary (in nursery shade and direct sunlight) acclimatization in coco peat, composted soil, and manured soil media were high - with survival percentages of 87.5-97.8% in three to four weeks.

Auxin and cytokinin synergism in micropropagation for mass production of Aloe vera

Aloe vera [Aloe vera (L.) Burm. f.] is considered a valuable medicinal plant worldwide due to its remarkable beneficial effects on human health. However, challenges in A. vera propagation hinder meeting the increasing demand in the health and beauty sectors. As an alternative method, in vitro propagation is crucial for the mass production of Aloe plants, which is a rapid method as well. Therefore, the present study aimed to establish an efficient micropropagation protocol for A. vera by in vitro optimization of the effect of different plant growth regulators (PGRs). For shoot proliferation, sterilized explants were inoculated on the Murashige and Skoog (MS) medium supplemented with 6-benzylaminopurine (BAP) and thidiazuron (0.5, 1.0, 2.0, and 4.0 mg/l) in combination with 0.5 mg/l naphthaleneacetic acid (NAA). Subsequently, indole-3-butyric acid (IBA) (1.0, 2.0, and 3.0 mg/l) was used for root induction. It was found that the explants cultured on the MS medium supplemented with 4.0 mg/l BAP + 0.5 mg/l NAA showed the highest percentage of response (90 ± 1.29) for shoot induction within the minimum number of days (5 ± 0.33). The highest number of shoots (2.7 ± 0.36) and length of shoots (4.7 ± 0.42 cm) per explant were also observed with the same concentration of PGRs. However, the highest number of roots (3.2 ± 0.57), length of roots (5.67 ± 0.21 cm), and root induction (80 ± 1.97 %) were noticed within the minimum number of days (11 ± 0.79) on the MS medium supplemented with 1.0 mg/l IBA. Thus, the proposed method is a quick and effective approach for the mass propagation of A. vera with appropriate dosages of auxins and cytokinins, which may allow meeting the increasing commercial demand.