PCR could enable more specific pollen forecasts

When it comes to allergies, not all grass pollens are equal. Some species trigger more asthma and allergic rhinitis (also called hay fever); others less. But all grass pollens look identical. This makes it devilishly difficult to provide detailed grass pollen forecasts for people with allergies. According to research led by Benedict Wheeler at the University of Exeter and Simon Creer at Bangor University, DNA analysis could help (Curr. Biol. 2021, DOI: 10.1016/j.cub.2021.02.019). Experts provide pollen forecasts by using a microscope and counting pollen grains. They can identify different tree pollens by eye—but not grass pollens—so allergy experts have been on the hunt for a solution. In 2019, the researchers showed they could use polymerase chain reaction (PCR) to rapidly identify grass pollen species based on their different DNA sequences (Nat. Ecol. Evol. 2019, DOI: 10.1038/s41559-019-0849-7). Now they have combined environmental samples from different sites in the UK with medical data about cases of asthma and prescriptions for allergy medicine. By tracking these variables from 2016 and 2017, the team found that allergies seem to correlate most with higher levels of two grass species: Cynosurus cristatus and Phleum pratense. In the future, the researchers say, pollen forecasts could give a species breakdown using their sampling technique.