The effects of pretreatment of ۴,۲-D on in vitro organogenesis of rapeseed (Brassica napus)

Rapeseed as the most important oil plant of Brassicaceae family has the varieties that are strong against tissue culture and transformation. Given that achieving a method and conditions of plant propagation from callus is the first step of a successful transformation program, in this study, the factors affecting the direct shoot regeneration of rapeseed cultivars, including Sarigol, RGS۰۰۳, SLM۰۴۶ and Orient, in connection with the pretreatment of ۴,۲-D(in three one-, two-week and control periods) as a factorial experiment with a completely randomized design with three replications and eight samples for each replication were studied. Firstly, the seeds were disinfected by sodium hypochlorite and then, cultured in MS medium in order to produce explants. ۵-day seedlings were used for the production of cotyledons explants and ۸-day seedlings were used for the production of Hypocotyl explants. The results of variance analysis showed that cultivar and applying pretreatment on the in vitro organogenesis of rapeseed impacted on all traits, including the frequency of shoots and hypocotyl regeneration and also the frequency of shoots and cotyledon regeneration. While the interaction of cultivar ۴,۲-D and also other interactions had no significant impact on the response of rapeseed to organogenesis. The results showed that one-week pretreatment ۴,۲-D was better than two-week and control pretreatments in terms of organogenesis that the least frequency of regeneration (۵۶%) of cotyledon explants was related to control pretreatment while the highest frequency of regeneration of hypocotyl explants was related to one-week pretreatment (۶۴%), so, the pretreatment of ۴,۲-D can be used for organogenesis of rapeseed, although it is suggested that the different levels of pretreatment and different cultivars of rapeseed will be investigated in future experiments.

Keywords:

shoot regeneration , callus induction , hypocotyl , cotyledon.