Mucilage Synthesis in Callus Cultures of Plantago ovata Forsk

Abstract

The seed husk of Plantago ovata known as psyllium (Isabgol) yields medicinally important mucilage. The amount of mucilage produced is about 25 % (by weight) of the total seed yield. In the present study, an attempt was made to increase the amount of mucilage through callus cultures of P. ovata. The first step involved establishment of callus cultures in P. ovata. Leaf explants from 10 to 20 day old seedlings were cultured on MS basal medium supplemented with various concentrations of different plant growth regulators. The highest rate of callus induction (89 %) was obtained on MS medium containing 0.5 mg l -1 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.0 mg l -1 Kinetin. The mucilage content was estimated from the callus obtained in different media. The best mucilage production was obtained in the MS medium supplemented with 0.25 mg l -1 2,4-D and 0.25 mg l -1 thidiazuron. Significant differences with regard to the total mucilage content were recorded. Overall, the callus produced nearly five times more mucilage than the seeds. The present technology provides an alternative route to production of large quantities of mucilage without plants.The seed husk of Plantago ovata Forsk, is an effective laxative. Seeds of P. ovata release mucilage in water, which is an anionic polysaccharide of L-arabinose, D-xylose and Dgalacturonic acid [1], and is used to treat diverticulitis [2], constipation, diarrhoea, haemorrhoids, bladder problems, irritable bowel syndrome, high blood pressure, high cholesterol and type 2 diabetes [3]. Mucilage of plant origin is in high demand nowadays, and it is very difficult to fulfil the entire demand by field grown plants only. For this purpose, a striking and very promising alternative system for commercial exploitation is the plant tissue culture by using cell suspension culture systems [4]. However, so far any attempts to increase mucilage have not yielded positive results in P. ovata. Studies along these lines have been conducted in Plantago lanceolata where in media having different combinations of plant growth regulators (PGRs) have been used to obtain mucilage from callus [5]. It has been reported that callus cultures are relatively rich in mucilage which commonly make up between 8-10 and 0.2-3.7 % of dry weight in some plants [6,7]. To the best of our knowledge, there are no reports on in vitro mucilage production from the callus cultures of P. ovata. Therefore, the present study was aimed to explore the possibility of mucilage production through in vitro culture.Seeds of P. ovata were available in the collection center of School of Biotechnology, University of Jammu, Jammu, India. The seeds were sterilized first with 70 % V/V ethanol for 1 min, then with 5 % w/v sodium-hypochlorite solution for 20 min, finally washed five times with sterile distilled water. The sterilized seeds were aseptically germinated on an agar-solidified MS basal medium [8] and incubated at a temperature of 25 ± 1°C. Leaf segments (1.5 cm) were excised from 10 to 20 day-old seedlings and were used as explants ...

Experimental Paper. In vitro synthesis of mucilage in Plantago ovata Forsk affected by genotypes and culture media

“…The differences between these callus induction rates could depend on the differences between assayed genotypes in response to callus initiation and different explants that were used in this study. The findings of the current study are in agreement with those of Gupta et al [7] who reported the highest rate of callus induction (89%) in P. ovata on MS medium containing 0.5 mg/l 2,4-D and 1 mg/l Kin on the leaf explants. Wakhlu and Barna [20] reported that the best initiation and growth of callus (fresh weight of callus) in P. ovata was achieved on MS medium containing 1 mg/l 2,4-D and 1 mg/l Kin with hypocotyl culture.…”

“…This study demonstrated explants and plant growth-regulator concentrations at high mucilage synthesis by employment of desirable genotype. Our findings are consistent with those of Gupta et al [7], Mirmasumi et al [22] and Afshar and Golkar [29] who have obtained relatively large amount of mucilage compound as a secondary metabolite in undifferentiated calli of P. ovata, P. lanceolata and Alyssum species, than the seeds obtained by field grown plants, respectively.…”

“…Gupta et al [7] reported that 0.25 mg/l 2,4-D and 0.25 mg/l TDZ (thidiazuron) produced the most mucilage content with callus culture (51.3% g/g DW) in P. ovata.…”

“…Plant-originated mucilage is in high demand nowadays, and it is very difficult to fulfill the entire demand by field grown plants only [7]. For this purpose, a striking and very promising alternative system for commercial exploitation is the plant tissue culture by using cell suspension culture systems [8].…”

“…With the above mentioned difficulties, callus culture has been an alternative and efficient source for the production of higher secondary metabolites using of somaclonal variation [18]. Different explants including shoot buds [19], hypocotyl [20], leaf [7] and root [21] have been used to induce callus in P. ovata. The optimization of medium ingredients, especially plant growth hormones, was the basic approaches in bioreactor system of the plant for mucilage production.…”