They is presently lots of talk about chromosome doubling. Here is a question from a novice.
Is it possible to create haploid plants by culturing pollen grains?
That is a great question! In some crops the details have been worked out. Henry Kuska and I have tried over the years as well as others, but so far in roses it has not been successful yet. Some of the keys that help are collecting immature anthers so the pollen is at a relatively early stage of development, culture them in darkness, and use some silver nitrate in the media (binds ethylene receptor sites so ethylene doesn’t encourage tissue to die). Haploid callus has been generated by some people, but successful shoots and plants haven’t been regenerated yet.
What are you interested in producing? Are you interested in getting diploids from tetraploids? It would be amazing to get a monoploid from a diploid. If so that would greatly help in sequencing the rose genome.
THere are other ways to get diploids from tetraploids. An egg that does not get fertilized and develops into an embryo naturally occurs sometimes. We just need to keep our eyes open for morphological features associated with diploids and check such plants to see if they are diploid. For instance, I have two diploids out of Rise N Shine. One was from a cross with a one time blooming species rose. One time bloom is dominant. There was one seedling that was petite, yellow and reblooming. It stood out and was easy to identify that way. Sometimes in seeds you can get twins with a smaller twin in the same papery testa coating as the larger one. SOmetimes they have the same genetic constitution as the egg (they are often derived from synergids).
There is a rather simple way to get around having to do tissue culture; cross a tetraploid with a distantly related diploid the resulting plant might be triploid and produce both tetraploid and diploid pollen. Therese Bugnet came of this and I use it too. If your interest is haploids plants these are a pain because haploid plants always carry a number of deleterious genes that are protected against in the diploid and higher. What one may believe is the fault of the culturing technique, it just a weakness of the plant. I don’t know if my rant is of any help. johannes