Abstract
Abstract During different phases of in vitro culture, plant tissues may be exposed to some stresses that never encounter in their natural habitats. The most significant stresses which interfere with in vitro culture are pathogenic contamination and browning disorder. Since browning sign is occurred during all phases of in vitro culture of Spartium junceum L., the present study was done preventing explants from browning during disinfection and callogenesis phases using exposure time of sterilants (ethanol 0, 30, 60 s and home bleach 0, 10, 15 min), antioxidant compounds (PVP 0.5%, Activated charcoal 0.1%, Curcumin 0.1%), Running water (30 and 60 min) plant growth regulators (2,4-D 0, 0.5, 1 and 2 mg L-1 and BA 0, 0.1 and 0.2 mg L-1), and by changing light/dark conditions was designed. The results showed that ethanol 70% (30 s) in combination with home bleach 20% (10 min) had the best effect in control contaminations and browning sign in nodal explants of S. junceum. The application of PVP 0.5% in medium was the best treatment to control of browning nodal explants in callus induction phase. The highest callus formation and the lowest explant browning were obtained on the medium supplemented with 0.5 mg L-1 2,4-D under the darkness condition. According to the results of this study, how disinfection methods, culture medium compositions and light conditions were effective on the browning and callogenesis of Spartium junceum L.
Highlights
During different phases of in vitro culture, plant tissues may be exposed to some stresses that never encounter in their natural habitats
In order to optimize disinfection and sterilization conditions, nodal segment explants were submerged in ethanol 70% for three periods (0, 30 and 60 s), the explants were placed into commercial sodium hypochlorite 20% for three periods (0, 10 and 15 min)
The results showed that applying home bleach for 10 min and 15 min increased browning degree in nodal explants
Summary
During different phases of in vitro culture, plant tissues may be exposed to some stresses that never encounter in their natural habitats. The most significant stresses which interfere with in vitro culture include plant pathogens contamination and browning (Taghizadeh et al, 2016). One of the too serious difficulties in micropropagation process is in vitro pathogens; they cause infection and so loss the tissue culture process at early stages, even though sterilization methods are applied (Al Ghasheem et al, 2018). Mercury chloride and silver nitrate have more powerful effects than others and have been applied frequently in past. Sodium hypochlorite and calcium hypochlorite make explants less injured because of their lower activity degree. They are able to induce necrotic explant and cell death in high concentration, and so cause browning of explants (Mahmoud and Al-Ani, 2016). In order to reduce browning degree, a number of approaches have been suggested (Krishna et al, 2008; Momeni et al, 2017)
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