Projects - dr. KJ (Karen) Kloth

What happens in the phloem? (VENI & PSG Strategic fund)

The phloem is a very interesting and mysterious tissue. The sieve tubes are the 'blood vessels' of plants that transport photosynthates and signal molecules. Sieve elements are largely empty cells that are connected via sieve plates into sieve tubes. The pressure in a sieve tubes can reach up to 10 bar, more than the pressure of your bike tire! When an aphid punctures the plasma membrane of a sieve element, lots of things sudden pressure drop, influx of ions, and release of non-self molecules derived from the aphid saliva and aphid stylet. Plant responses to such an event are crucial. Not only aphids are a threat for removal of precious phloem sap, also viruses use the conduits to spread and infect the plant systemically. In our research we discovered parallels between phloem-located defense responses to aphid attacks and virus infections. In this project we aim to identify which proteins play a key role in the defense of these interesting cells. In this project we work closely together with the Lab. of Virologie (WUR). Picture Karen Kloth.

Microbial imprinting for crop resilience to herbivorous insects (MiCRop Gravitation programme)

Plant roots house one of the most diverse, yet vastly neglected, microbial communities on earth. The aim of this project is to harness the genomic potential of root microbes as a new platform for improved resistance of plants to herbivorous insects. Hereto, we study the evolution of plant-microbiome interactions in the Brassicaceae family and identify opportunities for future plant breeding. Our focus is on understanding active recruitment of beneficial microbes in the soil by plants that are under attack of above-ground herbivorous insects. With precision-based methods, we analyse the root microbiome dynamics of over 30 wild and cultivated Brassicaceae species, and the effects of recruited microbes on plant defenses to chewing and piercing-sucking insects. This project is part of the MiCRop Gravitation programme, where we closely collaborate with five different institutes in the Netherlands to unravel the role of the soil microbiome of several plant families in enhancing resilience to a variety of biotic and abiotic stresses (https://www.microp.org/). The knowledge we generate in this programme will be used to develop microbial agents and genetic sources in collaboration with industrial partners to improve the resilience of crop systems to herbivory, pathogens, drought and phosphate starvation. Picture Hans Smid.

Cell-specific plant defense responses to aphids (VIDI)

Aphids are a major problem in pepper and other crop systems. This is due to the combination of a very efficient asexual reproduction system with exponential aphid population growth in monocultures, the large economic impact of aphid-transmitted plant viruses and the rapid adaptation of aphids to insecticides. In this project, we aim to find alternatives for insecticides. For this, we elucidate natural plant defense pathways and will contribute to new genetic markers to develop crop plants with stronger and more diverse natural resistance mechanisms, and microbial agents that activate plant defences. The interaction between aphids and plants is intricate. Aphids use their piercing-sucking stylet mouthparts to gently probe in between cells and secrete saliva to suppress wound responses (see //youtu.be/HEogJTdk9KY?si=QMgaStlYzr6s2uDG). Eventually they aim for the sieve tubes where they can passively ingest phloem sap, a sugar-rich nutrient source. We will elucidate cell-specific plant defense responses along that probing pathway of the aphid to prevent or retard the aphid in finding its food source in the phloem. In parallel, we investigate how to activate these defense genes via transcription factors and microbial inoculants. Our study systems consist of the green peach aphid (Myzus persicae), Arabidopsis, as a model plant with a vast range of molecular possibilities, and pepper plants and their wild relatives (Capsicum sp.). Picture Hans Smid, //bugsinspace.nl/