This is what happens if you keep a plant in culture over several years.
Repeat subculturing down the line ( as opposed to subculture from preserved parent plant tissue by methods such as cryo storage or storage media formulation ) inevitably leads to a degradation in plant quality.
In this instance poor quality was indicated by a wilting stem, occasional wilting and browning of older leaves, a lower proliferation rate and a radical decrease in deflasking success.
There are a number of ways around it, and they are different for each species- and in some cases each individual plant. In this instance we got best results from moving from a solid media to a liquid media- other media formulations didn't actually achieve good results
There is no telling how many generations it will take a plant in culture to become exhauseted or run out