Parasitic root galls & symbiotic root nodules – A comparison of how plant colonisers can manipulate plant organ development

This is one of the funded projects for our 2025 Undergraduate vacation bursary, click here to return to the list of 15 projects.

This project is going to be…	Experimental (lab/field based)
Institute	The University of Cambridge
Project supervisor	Dr. Katharina schiessl
Title of Project	Parasitic root galls & symbiotic root nodules – A comparison of how plant colonisers can manipulate plant organ development
Date of Project Commencement	16 June 2025
Duration (weeks)	8
Brief Description of Project	Root gall-inducing parasitic nematodes are major crop pests. By contrast, root nodule-inducing mutualistic rhizobial bacteria are major providers of nitrogen in the soil. Both of these plant colonisers induce and modify plant host organ development for their own purposes. However, there are large knowledge gaps of what plant developmental pathways are recruited, how they are modified and how they compare between coloniser-induced organs.Our previous work and work by others showed that the initiation of lateral roots, symbiotic root nodules and parasitic root galls converges on a common developmental program controlled by the transcriptional regulator LATERAL ORGAN BOUNDARIES 16 (LBD16) that activates the biosynthesis of the plant hormone auxin and promotes cell proliferation [1, 2]. Most recently, we identified nodule organ identity regulators of the LIGHT-SENSITIVE SHORT HYPOCOTYL transcription factor family [3]. Interestingly, genes of this family and their downstream targets are also induced during early stages of root-knot nematode infection and the formation of parasitic root galls [4]. In this summer project, we aim to investigate how root-knot nematode infection and the formation of parasitic root galls are affected by the gain and loss of function of these recently identified nodule organ identity regulators. For this, we will use the legume Medicago truncatula which is model for temperate grain legumes such as pea and faba bean. Medicago is a common host for N-fixing rhizobial bacteria and the root-knot nematode species Meloidogyne sp.. Therefore, it provides a useful framework to compare the plant developmental pathways that are targeted by both colonisers within the same genetic background and tissue context.We will perform time-resolved infection assays on gain and loss of function lines and investigate the cellular responses using tissue sectioning combined with light microscopy and deep tissue confocal imaging. In preparation for these experiments, we will generate gain of function lines performing Agrobacterium rhizogenes-mediated transient transformation experiments (hairy root transformation) and perform genotyping of tobacco retrotransposon Tnt1-insertion mutant lines in Medicago. The outcomes of this project will provide the foundation a large scale time-resolved gene expression profiling experiment where we aim to simultaneously profile the changes in gene expression in the host and the parasite (dual species RNA-Seq).The student joining this project at the intersection between molecular plant-microbe interactions and plant development will be trained in basic molecular biology techniques such as genotyping, Golden Gate cloning and plant tissue culture. Benefitting from the cutting-edge bioimaging facility at the SLCU, the student will have the opportunity to his/her microscopy skills. Furthermore, SLCU offers a vibrant research environment for summer students. Recommended reading for the project[1] Schiessl et al., Curr Biol 29 (2019) [2] Cabrera et al., New Phytol 203 (2014)[3] Lee et al., Curr Biol 34 (2024) [4] Yamaguchi et al., Front. Plant Sci 8 (2017)