Facing the Phloem: Karen Kloth
An interview with plant biologist & entomologist Dr. Karen Kloth of Wageningen University
Dr. Karen Kloth studies plant-aphid interactions. Understanding how the host plant defends itself against its insect predators teaches Karen about the underlying mechanisms at work in both creatures - and about how we might phase out insecticides for more sustainable agriculture! She is vastly knowledgeable in her field yet humble about how much is still unknown. She is fascinated with the natural world yet patient with the delicate research methods needed to study it. We are so grateful to have Karen as an advisor.
How did you get involved in the field of plant biology & entomology?
I knew I wanted to become a biologist as a 10-year-old and ran around with nets to catch dragonflies in my teens. Although my initial dream was to become a marine biologist and study whales, I realized during my MSc Biology at Wageningen University that insects are just as cool, easier to experiment with and have fascinating interactions with plants that cause big problems in agriculture.
What has been your most exciting finding so far?
My most exciting experience was to discover a plant gene that protects plants against aphids. After several years and many efforts in finding plant resistance genes, I suddenly observed huge effects on my aphids. They didn’t want to feed from plants with this gene. We had no clue what this gene was encoding. I will never forget the moment when I was sitting alone at the microscope, the first time face-to-face with my phloem protein, that was amazing!
Phloem: The living tissue in vascular plants that conducts sugars and other metabolic products downward from the leaves. The phloem is the site of long-distance electrical signaling in plants, making use of its long, tube-like cells and broad plasmodesmata (cell-to-cell openings).
Tell us about the moment you felt most strongly connected to nature.
Sitting as a kid on top of the hill in my family’s pasture, looking out over the valley and the forests.
What do you think is necessary for humans to regain our sense of interrelatedness with our natural ecosystems?
Experiencing that nature is bigger than us.
Aphids are highly specialized insects. They have evolved needle-shaped mouthparts, called stylets, with which they feed on the sugar-rich phloem sap of plants. Without harming cell integrity, they navigate their stylets through the plant cell wall to reach a phloem tube. After salivation in the sieve tube, they can ingest phloem sap passively for hours or days.