Plant cell cultures: Chemical factories of secondary metabolites

Efficient protocols of axillary bud multiplication and indirect organogenesis were established for Holostemma ada-kodien Schult. (Asclepiadaceae). Murashige and Skoog (MS) medium supplemented with 2.0 mg l–1 N6-benzylaminopurine (BAP) and 0.5 mg l–1 indole-3-butyric acid (IBA) induced an average of eight shoots per node and was the best for axillary bud proliferation. Subsequent cultures enhanced the number of shoots. The explant source of callus and the growth regulator inducing the callus exhibited significant influence on organogenesis. Callus developed from the basal cut end of the node explants differentiated more than 15 shoots on MS medium fortified with 1.5 mg l–1BAP. Callus from internode explants developed fewer shoots than callus from the basal cut ends of node explants. Leaf-derived callus did not undergo organogenesis. The abscission of leaves and shoot tips of the developed shoots was prevented by the addition of AgNO3 or CoCl2, but with a concomitant significant reduction in the number of shoots. Half-strength solid MS or liquid medium with 0.05 mg l–1 IBA exhibited the best in vitro rooting. Ninety percent of the rooted shoots survived in the field.

Rapid propagation of Holostemma ada-kodien Schult., a rare medicinal plant, through axillary bud multiplication and indirect organogenesis

Caulogenic responses of various explant types from 12-month-old plants of Hemidesmus indicus were tested Second and third visible nodes (05 cm) from the apex and root segments (05 cm) were the most and least regenerative respectively, with the formation of 937 and 26 shoots in 4 weeks on half strength MS medium supplemented with 222 μM BA and 107 μM NAA and 444 μM BA and 269 μM NAA respectively Caulogenic ability of the nodes decreased with increasing maturity Shoot buds initiated upon the young nodes on day 10 developed into 72 cm long shoots within 4 weeks thereby making a shoot elongation phase unnecessary Nodal explants of the in vitro raised shoots subcultured in the same medium produced 932 shoots of 71 cm length in 3–4 weeks, similar to those of the mature plant-derived nodes Multiplication through subculture of the nodes up to 25 passages of 4 weeks each was achieved without decline Shoot cultures were rooted in quarter salt strength MS medium containing 98 μM IBA and the rooted plants were hardened for establishment in pots at 96% rate Four months after establishment, the micropropagated plants were stable and showed uniform morphological and growth characteristic After 12 months of cultivation in the field, on an average micropropagated plant consisted of 4–5 shoots, 5–8 branches per shoot and increased root biomass (135 g) compared to the poor growth (single shoot and 2–3 branches) and root production (46 g) values obtained with plants raised from conventional rooted stem cuttings The concentration of the root specific compound, 2-hydroxy 4-methoxy benzaldehyde per plant was 2–3 fold higher in micropropagated plants though on unit dry root biomass (012% per g dry wt) basis it remained the same between two sources of plants

Micropropagation of Hemidesmus indicus for cultivation and production of 2-hydroxy 4-methoxy benzaldehyde

Protocol for rapid in vitro propagation of Ceropegia candelabrum L. (Asclepiadaceae) through axillary bud multiplication was established. Murashige and Skoog (MS) medium with 8.87 μM N
6-benzyladenine (BA) and 2.46 μM indole-3-butyric acid (IBA) was best suited for axillary bud proliferation inducing a mean of eight shoots / node. Excision and culture of the nodal segments from the in vitro shoots on fresh medium with same concentrations of BA and IBA facilitated development of more than 10 shoots / node. Subsequent cultures enhanced the rate of shoot proliferation. Shoots developed were rooted best on half strength MS with 0.49 μM IBA. Starting from a single node explant, 250 rooted shoots were obtained within 120 days. Plantlets established in pots exhibited 90% survival. Plantlets successfully established in field exhibited morphological characters identical to mother plants.

Rapid in vitro propagation of medicinally important Ceropegia candelabrum

The root bark essential oil of Periploca sepium Bunge (Asclepiadaceae/ Apocynaceae) obtained by hydrodistillation was investigated by GC and GC-MS. 2-Hydroxy-4-methoxybenzaldehyde was found to be the main component (78.8% of the total) among 17 identified compounds. 2-Hydroxy-4-methoxybenzaldehyde was separated and purified by preparative thin layer chromatography, and was further identified by means of physicochemical and spectrometric analysis. Both the essential oil and 2-hydroxy-4-methoxybenzaldehyde exhibited antimicrobial activities on all test bacteria and fungi, with MBC/MFC values ranging from 125 microg/mL to 300 microg/mL, MIC values from 80 microg/mL to 300 microg/mL, and IC(50) values from 63.29 microg/mL to 167.30 microg/mL. They also showed moderate antioxidant activity in the DPPH free radical scavenging, beta-carotene bleaching and ferrozine-ferrous ions assays. The results indicated that the major portion of these antimicrobial and antioxidant activities was due to the presence of 2-hydroxy-4-methoxy-benzaldehyde in the oil, which could potentially be developed as an antimicrobial and antioxidant agent in the future.

https://www.mdpi.com/1420-3049/15/8/5807/pdf

Antimicrobial and antioxidant activities of the root bark essential oil of Periploca sepium and its main component 2-hydroxy-4-methoxybenzaldehyde.

Nodal explants of Hemidesmus indicus plants cultured in half strength Murashige and Skoog medium fortified with 2 mg indole-3-butyric acid l−1 in the dark produced 10–12 roots (1–2 cm) with minimal callusing in 10 days. Roots, ∼20 mg dry wt, cultured in Gamborg et al. medium supplemented with 2 mg IBA l−1, sucrose (4% w/v), pH (5.6) and agitation (70 rpm) in the dark yielded 550 mg root dry wt/flask and 0.18% 2-hydroxy 4-methoxy benzaldehyde in the roots after 30 days. The maintenance of normal morphology of the roots, consistent biomass and product yields over a 21-month period indicated the stability of the cultures. © Rapid Science Ltd. 1998

S. Sreekumar

Papers

Micropropagation of Hemidesmus indicus for cultivation and production of 2-hydroxy 4-methoxy benzaldehyde

Production of 2-hydroxy 4-methoxy benzaldehyde using root cultures of Hemidesmus indicus