I read a paper called Estimation of genetic variability, mutagenic effectiveness and efficiency in M2 flower mutant lines of Capsicum annuum L. treated with caffeine and their analysis through RAPD markers (https://www.researchgate.net/publication/303511060_Estimation_of_genetic_variability_mutagenic_effectiveness_and_efficiency_in_M2_flower_mutant_lines_of_Capsicum_annuum_L_treated_with_caffeine_and_their_analysis_through_RAPD_markers) where, as the title suggests, they subjected Capsicum annuum seeds to a 1% solution of caffeine which lead to mutations in the plants. In particular the paper shows pictures of mutated flowers in the M2 generation.
I tried it myself on Solanum villosum seeds, without the phosphate buffer, and with no success. No seeds germinated.
Perhaps it's due to the lack of the phosphate buffer or maybe I overshot the caffeine concentration as I used a cheap scale to measure the caffeine.
Has anyone tried this or does anybody know any other relatively safe mutation breeding techniques?
I made some caffeine-resistant mutants of the fungus Schizophyllum commune back in the 1970s. Don't remember much about it now. Also have used EMS (ethyl methane sulfonate) and Xrays as mutagens. This was all in the context of having a full-scale molecular bio lab with access to an Xray setup, etc. Usually mutagens are seriously dangerous. However, it should be possible to use caffeine as a mutagen even if your ability to weigh it isn't great.
Usually when you use a mutagen on a new system, you have to figure out the right dose of mutagen for your system. Even if the paper you were using as reference was using caffeine as a mutagen on solanum seeds, it would be a "different system" when you were trying to mutagenize seeds of a different solanum species.
You usually start off doing one experiment just to get the approximate range of concentrations of mutagen. Most mutagens will kill all the biological material at a certain concentration, at a bit less will cause so many mutations you have an unworkable mess with multiple mutations in everything and too many viability problems. At a just right concentration you have a mix of material with much with no mutations and much with just one mutation per biological entity each. At a yet lower concentration of mutagen you have to look hard to find any mutants. And below that you don't get enough mutants to be worth looking for them. You also always have a no mutagen control. Maybe the seed was all dead.
Usually it takes one preliminary experiment to figure out the roughly approximate range of mutagen levels. Then when you do the mutagenizing for real you still use a few different concentrations. Just a narrower range than the first time. If you do it many times on some runs the optimal level of mutagen is one amount and sometimes slightly different. This is even if you have your own fancy biochem lab with an analytical balance. Biology ain't physics. Us biological entities are an unruly lot.
If you are doing it that way it should work even if your ability to weigh things isn't stellar. And if you go get yourself a better balance, you will still need to establish the workable range of concentrations of mutagen in your system yourself, as well as use multiple concentrations in any mutagenizing run to accommodate the variability of everything when doing biology.
Thank you for the reply Carol. Indeed I did not run a control, but it's unlikely that the seeds were dead because I planted the same batch about a month earlier and had great success with germination.