Invisible plant world: DNA research on pollen and seeds

Without us always realizing it, plants are present everywhere in their smallest form. This includes decaying leaf material and tiny seeds to microscopic pollen that is often almost invisible in the environment. Although minute, these plant fragments contain a vast wealth of information. Meise Botanic Garden, in collaboration with KU Leuven, is engaged in the European MetaPlantCode project, supported by the Research Foundation – Flanders (FWO), to map the diversity of pollen and seed mixtures through five socially relevant studies:

The hay fever puzzle: which grass species bloom during the grass pollen season?

Nearly one in five Belgians suffers from a grass pollen allergy, especially between May and September, during the grass pollen season. This season is characterized by the successive blooming of various grass species. For many years, Sciensano has monitored this period using microscopic techniques, but these methods cannot accurately distinguish between the pollen of different grass species. In this new study, conducted in collaboration with Sciensano, we analyze the DNA of airborne pollen to better understand the flowering periods of specific grass species during the pollen season. These insights could lead to a more targeted approach to managing hay fever symptoms.

Controlling the oak processionary moth: which plants attract its natural predators?

The urticating hairs of oak processionary caterpillars can cause severe skin irritation in humans and animals, making these caterpillars unwelcome in gardens and parks. They can be naturally controlled by parasitic tachinid flies. These adult flies feed on the nectar of nearby flowers, but their flower preferences remain poorly understood. In this joint study with the Research Institute for Nature and Forest (INBO), we analyze the DNA of the pollen found on the bodies of adult tachinid flies to identify their preferred flowers. This information could help park managers naturally attract these beneficial predators.

Identifying seeds for ecological restoration: which valuable plant species' seeds are already present on restoration sites?

As part of the EXPBIO project, Meise Botanic Garden is working on restoring natural grasslands. Germination experiments are being conducted to determine which plant species' seeds are already present in the plots targeted for restoration. To complement these experiments, we also analyze the DNA of seed mixtures collected from the same plots to study the diversity of plant species. This knowledge can be used to accelerate similar restoration experiments in the future.

A journey back in time: what did the flora of Flanders look like thousands of years ago?

Over the past millennia, plant diversity in Flanders has fluctuated with changing climates. Insights into these changes have mainly come from microscopic analyses of sediment cores. In collaboration with the archaeobotany lab at Ghent University (UGent), we extract DNA from pollen and macroremains found in these sediment cores to identify the plant species more accurately. These findings contribute to a broader understanding of the evolution of plant diversity in Flanders.

How stable is the pollen composition of soils throughout the year? a methodological study.

Each plant species blooms at a specific time of the year, which likely causes the composition of pollen in the upper soil layers to change accordingly. This fifth study aims to investigate how the pollen composition of soil samples varies throughout the year to better understand how sampling time influences the results. This study is being conducted simultaneously in several European countries to examine these effects across a wider geographical range.