I am a graduate student and to earn my keep I help run a tissue culture lab. A student took home a petri dish of orchids and emailed me this question. I don't know the answer and would appreciate any information that someone may be able to share. Question: my petri dishes with the orchids and ferns were doin great and then all of a sudden one day the orchids all turned white except for a couple. i dont know y. thers some moisture inside the dishes and they were looking great and then bam white. i had them in a window that had some non direct sun-could they have not been getting enough sunlight? could they have ran out of sugar and starved? or not enough light? for a while i had them under a plant light could i have bleached them or maybe it was a bad light so it really wasnt giving them any help with photosynthesis? Thanks for the help.
Looks like the dish may have overheated. Not sure about how strong the indirect light was, but if any direct sun hits dish, the inside can quickly overheat. Sunlight might also be too strong. I would recommend placing the dish under cool flourescent lights in a room where the temperature is around 25C.
From the picture, it looks like it's forming callus, once cell begin to undifferentiated, you need to begin adding hormones and other nutrients to get them to form embryos and then shoots. If the cells look brown, then they are oxidizing and need to be transferred to another culture.
