Extracting DNA from single pollen grains is possible (see study on Hawaiian bees and their foraging "Pollen foraging behaviour of solitary Hawaiian bees revealed through molecular pollen analysis" Wilson et al 2010. We have done some work on this and have replicated their success. The hardest part is keeping track of smaller grains.
If you are asking about this in an ancient DNA setting, then it becomes much harder as the DNA is fragmented and partly decomposed. DNA that is beginning to decay becomes very much a specialty undertaking by an ancient DNA lab, where they can maintain the highest cleanliness/air exchange protocols.
Extracting DNA from single pollen grains is possible (see study on Hawaiian bees and their foraging "Pollen foraging behaviour of solitary Hawaiian bees revealed through molecular pollen analysis" Wilson et al 2010. We have done some work on this and have replicated their success. The hardest part is keeping track of smaller grains.
If you are asking about this in an ancient DNA setting, then it becomes much harder as the DNA is fragmented and partly decomposed. DNA that is beginning to decay becomes very much a specialty undertaking by an ancient DNA lab, where they can maintain the highest cleanliness/air exchange protocols.