Cell & Systems Biology
University of Toronto
Photo by: James Bradley
Welcome to the Lumba Lab!
We are group of diverse and collaborative researchers interested in the molecular mechanisms of dormancy and germination in plants. We use systems biology approaches which integrate genomics, transcriptomics and protein-protein interaction data to generate signalling networks underlying germination in the model plant Arabidopsis thaliana and in parasitic plants, such as Striga hermonthica.
Keep scrolling for a summary of our research interests!
The work carried out in the Lumba lab aims to:
Discover the identity of the molecular components involved in perception and downstream signalling of SLs, GA and ABA.
Determine how these components function at the molecular level to eventually lead to a germination response.
Part of this research is conducted in the model plant, A. thaliana, as the large body of knowledge of this plant, its short life cycle and its genetic tractability, make is a superb study system. For example, the early steps involved in SL perception in A. thaliana have now been well characterised (summarised in image below) and has provided the basic knowledge required to understand these signalling networks in other plants that have more direct agricultural and/or economical implications.
Germination is a crucial developmental decision made by the majority of living plants, and getting this decision right is crucial to the plant's survival. Like most developmental decisions, germination is co-ordinated by plant hormones. Three of the most notable plant hormones that are involved in this coordination are strigolactones (SLs), gibberellic acid (GA) and abscisic acid (ABA).
Why study germination in the model plant
Strigolactone Perception in A. thaliana
Early events of strigolactone signalling. An alpha/beta hydrolase receptor binds and hydrolyzes SL. The D-ring within the binding pocket forms a covalently linked intermediate molecule (CLIM) within the receptor (inset box). This results in a conformational change of the receptor that recruits an F-box-ASK complex. The protein complex results in the degradation of target proteins through the proteasome, thus releasing SL signaling from repression. Image from Lumba et al. (2017) Trends in Biochemical Sciences, 42(7).
Understanding Germination in Parasitic Plants
Work in the lab is also intently focussed on using knowledge garnered from A. thaliana to guide the study of germination in parasitic plants that cause severe agricultural problems. The hormone signalling networks controlling plant germination are malleable through evolutionary time, and this has allowed plants with different ecologies to tailor their germination responses to a range of environmental cues.
A fascinating example of this comes from parasitic plants within the Orobanchaceae family. The seeds of these parasitic plants have re-wired their germination signalling networks such that they will only germinate when they detect SLs that are exuded from host roots. This is an excellent adaptation for the parasite, as it ensures germination occurs only when resources required for its growth (i.e. a host plant) are available.
However, this creates an agricultural problem, as unlike common weeds, some root parasitic weeds of the Orobanchaceae family do severe and irreversible damage to their crop hosts before emerging above ground (i.e. before farmers know their crops are infested). Hence, understanding the signalling networks underpinning germination is seen as a crucial step in the fight against these parasites.
The research conducted in the Lumba lab is helping to uncover the mechanisms that allow these parasitic plants to co-ordinate their germination with host plants. In doing so we are providing the knowledge necessary to develop integrated and sustainable control strategies against these pernicious weeds.
Summary of Research Interests
1. Understanding the 'germination code' of parasitic plants
- Molecular mechanisms of dormancy and germination in Striga
2. Utilizing protein interaction networks
- Large-scale proteome approaches to construct hormone signalling networks
3. Using systems biology
- Integration of 'omics' data to generate dynamic signalling networks underlying germination
4. Understanding the evolution of germination networks
- Comparison of signalling networks from parasitic and non-parasitic plants