Assaad lab research interests
Plant resilience to future climate
Our core interest is how plants adapt to multiple stress conditions, especially heat, drought, and low light. We are tackling this question at all levels: ecosystem, organism, organ, cellular, genetic, molecular and biochemical.
At the ecoysytem level: here we are looking at forest ecosystems and using the state-of the art TUMmesa ecotron to simulate future climate scenarios. Sapling mortality is a key factor impeding forest restoration efforts. Our study focuses on a combination of Quercus petraea and Fagus sylvatica, the two most common broadleaf species in Germany and both of high relevance for central European forest ecosystems under climate change. A primary question we address is how saplings withstand not only drought alone but also heat alone and the combination of the two. We are monitoring con- and inter-specific competitive exclusion and sapling mortality in pure versus mixed cultures. The topology of growth (where growth occurs), shade-avoidance responses (elongated internodes and petioles) and photosynthetic parameters have been monitored as well. We aim to develop deep neural network models trained on synthetic data generated with computational models for inferring specific sapling growth parameters. Then, we aim to find a mapping from RGB image data of beech and oak saplings to computational parameters of sapling development and health. Our main objective is to determine survival thresholds along opposing gradients of light intensity, water stress and heat stress. This is an interdisciplinary research effort involving collaboration between physiologists, ecologists and computational scientists. This study will yield a deeper understanding of how the abiotic factors dought and heat as well as their combination act on oak and beech saplings, and what this implies for forest practitioners.
Link to a 4 min video of the saplings in the climate chambers: https://syncandshare.lrz.de/getlink/fi935NXyDHtkiYo2SzV2y1/22-109_TUM_Botanik_Schnitt_Master4.mp4
This project, klifW021, is funded by the Bayerische Landesanstalt für Wald und Forstwirtschaft (LWF) & StMELF. https://www.stmelf.bayern.de/
At organism, organ and cellular levels: here we are studying growth tradeoffs in Arabidopsis in response to future climate scenarios consisting of multiple stress conditions and erratic or contradictory stimuli. We have deployed two tools that have been used in decision theory: a well-defined yet limited budget, as well as conflict-of-interest scenarios. An assessment of organ and cell length suggested that hypocotyl elongation occurred predominantly via cellular elongation. In contrast, root growth appeared to be regulated by a combination of cell division and cell elongation or exit from the meristem. Our findings uncover a novel paradigm for root growth under limiting conditions, which depends not only on hypocotyl-versus-root trade-offs in the allocation of limited resources, but also on an ability to deploy different strategies for root growth in response to multiple stress conditions (Kalbfuß et al., 2022).
At genetic, molecular and biochemical levels: here a broad range of screens have uncovered a three-component module. The first component of the module is a family of shaggy-like kinases (AtSKs), which mediate signal integration (Kalbfuß et al., 2022). The second component is the conserved TRAPPII guanine exchange factor (GEF) that mediates decision-making processes at the trans-Golgi-network (TGN; Jaber et al., 2010; Thellmann et al., 2010; Rybak et al., 2014; Ravikumar et al., 2018; Garcia et al., 2020). The third component comprises a family of Rab GTPases that are posited to execute decisions downstream of the first two components (Kalde et al., 2019).
We are currently (1) elucidating the impact of post-translational modifications on the assembly, interactomes and GEF function of TGN-associated TRAPP tethering complexes, (2) characterizing functional interactions between TRAPP complexes and Rab GTPases, and (3) assessing how these instruct sorting and trafficking decisions. We are identifying molecular mechanisms by which signaling at the TGN modulates sorting decisions that contribute to cell division, elongation, growth anisotropy and meristem function. Mechanistic insights gained here are laying down a foundation for understanding plant adaptive growth, allocation decisions, and resilience to future climate. With changing climate, the cues that guide plant growth decisions have become more erratic; in some cases, these cues even appear contradictory, as in the case of mild winters followed by late frosts or of drought followed by flooding. Understanding decision making in plants and how such processes respond to erratic or contradictory cues becomes imperative.
The Assaad group chairs a forum in which students and faculty unite with industry, government and non-governmental organizations to debate existing mitigation goals.
In a joint project with the Carnegie institution on Stanford campus, our global MarieCurie fellow Frej Tulin aims to elucidate the core networks that control cell proliferation in Chlamydomonas and other green algae. The results from the project may help define biological constraints on microalgal biomass production, an important step towards realization of the potential of this diverse group of organisms as factories for technical materials and as carbon sinks. This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 798198.
Farhah has had a formative experience working with Ernst Goetsch on regenerative agriculture or syntropic agroforestry. These are highly productive and diverse systems and the issue of scalability is a huge challenge. Here, the embedding of our research consortium in the Unternehmertum/ Venture labs/ TUM “ecosystem” can help leverage sophisticated neural networks (in collaboration with our colleagues at the AMU), software, robotics and aerospace technologies.