Novel medium for enhancing callus growth in hazel (Corylus avellana L.)

Abstract

Paclitaxel is a powerful antimitotic agent with excellent activity against a range of cancers. Hazel has been described as a paclitaxel-producing species among angiosperms. Fast-growing callus is a prerequisite for the success of callus production and then paclitaxel production. Therefore, optimizing the medium culture for enhancing callus growth is a crucial step for paclitaxel production. In this research, Murashige and Skoog (1962) (MS) medium was optimized for improving callus growth of hazel (Corylus avellana L.). The M 10 medium (MS medium with pH 6.0 and supplemented with 1000 mg l −1 spirulina powder, 1000 mg l −1 casein hydrolysate and 3 g l −1 gelrite) significantly improved hazel callus growth. This modified MS medium increased callus fresh weight (55.8%) as compared to the control. M 10 medium increased fatty acids yield of callus (66.7%) as compared to the control. Liquid M 10 medium maintained growth over a longer period of time and also increased slightly, the paclitaxel production as compared to the control. This novel medium is promising for facilitating the mass production of hazel callus as a source of valuable metabolites including paclitaxel, linoleic and oleic acids.Paclitaxel is a powerful antimitotic agent with excellent activity against a range of cancers 1 . The major limitation in the extensive use of this valuable secondary metabolite is its low supply, since Taxus spp. contains very low amounts of paclitaxel 2 . Extraction of paclitaxel from this tree has imposed important ecological effects, resulting in the extinction of Taxus species 3 . Plant cell suspension culture is considered as the most promising approach to the production of paclitaxel 4 . The availability of this drug is still restricted and its cost is very high, mainly due to the recalcitrant behavior of Taxus spp. under in vitro conditions 2 . Therefore, the search for alternative sources of paclitaxel was considered as crucial. In addition to Taxus spp., hazel (Corylus avellana) has also been described as a paclitaxel-producing species through bioprospection among angiosperms 5,6 . The major advantages of producing paclitaxel through hazel cell cultures are that hazel is widely accessible and its in vitro cultivation is easier than that of yew 2,7 . It is stated that in vitro cultures of C. avellana can become a promising and cheaper source for paclitaxel production 8 . Besides the use of the nuts of hazel tree as a source of protein, its leaves are used to relieve the symptoms of hemorrhoidal and varicose veins 9 . The kernel and green leaf/flower portions of the hazel tree have antioxidant activity 10 . It is found that the consumption of nuts is protective against cardiac morbidity and mortality 11. In addition to the use of hazel cell cultures for paclitaxel production, hazel plantlets can be regenerated from callus tissues by differentiation induced by exogenous growth regulators. Plant regeneration from calli is possible by somatic embryogenesis or in vitro organogenesis. Meanwhile, infrequent somaclonal variants...