I do cotton tissue culture and use cotton seedlings as my explants. Normally at early stages of callus induction you should subculture your tissues on new media weekly or bi-weekly basis. The accumulation of phenolic compounds around tissues and in the media is toxic for explants.

Hi Rohollah

The prime cause of browning in woody plants is mostly because of phenol compound exudation. Due to excess phenol exudation growing tissues can not absorb mineral nutrients and ultimately leads to explant death. You can try several methods for phenol control like frequent sub culturing, initial dark treatment, usage of anti oxydents like ascorbic acid, citric acid, use of charcoal, adding antioxidents as media supplements, waxing the explants etc.

Try adding citric acid in medium. Hope it helps.

I do avocado tissue culture. Browning can overcome by adding Ascorbic acid in media. You will have to test the concentrations. But i suggest start with 100 mg/L and see the results. You can add very little amount of charcoal less than 1 g/L as well.

well Sir

Try with Activated charcoal / Ascorbic acid sir

Add ascorbic and citric acid in a ratio of 1:1 ranging from 40- 100 mg/l each depending on the severity of phenolic compound released in the culture. After 2-3 cycle there will be no need to use again to control browning.

As using Ascorbic and citric acid Read also the attached files

You can try with different concentration of Activated charcoal and some report says, even the silver nitrate can be used to minimize the browning reactions. Better to remove the basal part (~0.5 cm) of shoot tip for better growth of shoot tip.

Best Wishes

the nutrition media should be changed each week until the explants stop phenolic release and ascorbic acid should be added nutrition medium

What about contamination with microorganisms? I recommend you, as some other researchers here have done, refresh continuously combining with selection of new formed shoots to continue with culture: as can be seen in the picture, some greenish "shoots" have been formed that can be used for.

This is the better way to find the solution. Please provide the picture of explant, the number days in culture phase (2-3 weeks), take the picture and and compare yourself and provide to other for better suggestion. The displayed picture appears to be of over 5-6 week in culture phase.

Dear Ruhollah

Is the culture medium brown too, or is the explants brown and died?

Ruhollah Abdolinejad, all the tree sp. have this problem generally and this is due to phenolic leaching from the explants. Treat the explants with antioxidant solutions before inoculation and the addition of some antioxidants in the medium will solve the issue. For details read some of our articles on the tissue culture of trees you will get an idea about it. All the best..

Ruhollah Abdolinejad,

What type of treatment you have given to the explants prior to inoculation it is not clear that whether you have treated it with any antioxidant or not.

However apart from some names suggested above, you can also give cold PVP treatment (0.01%) for 4-5min before other anti-fungal or anti-bacterial treatment. It worked for us.

From photo it seems that u have got good shoots so u can also try to subculture that green portion and see that whether it grows normally and it also turns brown. If u observe browning of tissue again than u can go for addition of antioxidant in medium, but if not than u can go for explant treatment.

All the best.

Ruhollah Abdolinejad,

It is due to the phenolic exudates by the explant, to avoid browning and allowing explant to uptake the nutrients please treat the explant with antioxidants and also try to add Activated charcoal or ascorbic acid to the media